Re: [Emc-users] Question about closed loop CNC

[Karlsson & Wang]

In a closed loop their is feed back, read about control theory. Stepper motors 
are usually run open loop and no feedback is needed although they may loose 
steps if not correctly tuned.

Nicklas Karlsson


On Mon, 18 Jan 2016 23:04:05 -0800
Chris Albertson  wrote:

> I've read that it is hard to use steppers for closed loop CNC.  If this is
> still true could some one explain the theory.
> 
> I have a small mill with DRO scales that are good to about .001 inch and
> I'd like to put them to use with my planned CNC conversion.   I understand
> software.  I've worked in the field for 30 years and have experience with
> Linux (and other OS) device drivers, embedded real time code and so on.
> If the problem is simply that no one has bothered to write the code, I can
> fix that.   But if there is something of a mechanical nature I'm not
> thinking of maybe some one can point me at what I need to read up on.
> 
> At least I think I might be able too automatically measure backlash using
> the DRO scale data.  But my goal is to go closed loop if I can
> 
> -- 
> 
> Chris Albertson
> Redondo Beach, California
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Re: [Emc-users] A heads up on IDC ribbon connectors from China

[Karlsson & Wang]

It is rather easy to strip away one or a few if necessary.



On Thu, 14 Jan 2016 09:56:08 +
Lester Caine <les...@lsces.co.uk> wrote:

> On 14/01/16 04:19, Gene Heskett wrote:
> > Seems like the right thing to do, or buy 25 
> > wire cable, hard to find though.  Up to now I had assumed that ribbon 
> > cable always came in even numbers of conductors.
> 
> I've a reel of 25 way on the shelf, and none of the plugs or sockets
> have space for the 26th wire. Same on the 9 way D I use in the
> Divisiomaster, but I strip down the 10 Way cable used for the keyboard link.
> 
> -- 
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> -
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Re: [Emc-users] Xenomai, machinekit

[Karlsson & Wang]

> > linuxcnc.org has no xenomai kernel support in its stable or development
> > branches.  The version in what is now the machinekit fork was never made
> > into a form that could be merged with standard linuxcnc.  This doesn't
> > mean that no Xenomai support can ever be merged, but nobody seems to be
> > doing the work.
> >
> > Jeff
> >
> 
> Its also a bit doubtful what advantage Xenomai has over current Preempt-RT 
> kernels on modern hardware

Xenomai and RTAI also handle priority for code executed from interrupt although 
there still is SMI. There is enough computing power but sometimes it happens 
CPU is not avaiable then needed.

New microcontrollers with a Cortex CPU have a nested interrupts with prioirity 
and I often used it as a hardware scheduler. Even though micro controller run 
at much lower clock frequency scheduling is perfect so it is a big difference.


Nicklas Karlsson

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[Emc-users] Xenomai, machinekit

[Karlsson & Wang]

Do anybody know how to compile for xenomai?

I use the xenomai kernel. Linuxcnc I compiled myself run in user space and 
there is a huge difference between this and the version from machinekit which 
use xenomai real time.

Regards Nicklas Karlsson

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Re: [Emc-users] Stepper Motors/Drives

[Karlsson & Wang]

> Hey Guys,
> 
> I have never dealt with stepper motors/drives and one of the guys at our 
> shop is kicking around converting and old 9x30 Southbend lathe to cnc 
> using Linuxcnc. Are there any recommendations on maybe some kits with 
> all the power stuff (motors, power supplies, cables, etc,) that anybody 
> recommends. I am up in the air on the control hardware, but I can handle 
> that, I just don't know where to start on sizing/selecting the stepper 
> stuff.

You have to find suitable voltage and currents for the stepper motors.

Nicklas Karlsson

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Re: [Emc-users] Z axis stepper gradually losing position (opto coupler speed)

[Karlsson & Wang]

> ...
> I take it you do not have any opto-isolation in those 3 paths.  That 700 
> ns is pushing an opto's ability to switch that fast.  The BoB I used was 
> all opto, and I was warned about its speed by someone (Steve Stallings?) 
> on this list.
> ...

Yes opto couplers are not very fast, I think around a few hundred kilobits per 
second could be expected for opto couplers if used for UART, obviously there 
have to be some margin to unless pushing the limit is necessary.

Nicklas Karlsson

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[Emc-users] Intel Xeon, Real time performance

[Karlsson & Wang]

Old servers with intel Xeon are often for sale rather cheap, have anyone tested 
how they perform in the latency test?

Nicklas Karlsson

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Re: [Emc-users] Intel Xeon, Real time performance

[Karlsson & Wang]

25k? Should it be 25µ?

I tried POS terminals, they have touch screen but delay is not good.


> On 10 November 2015 at 20:10, Karlsson & Wang
> <nicklas.karls...@karlssonwang.se> wrote:
> > Old servers with intel Xeon are often for sale rather cheap, have anyone 
> > tested how they perform in the latency test?
> 
> I have a first-generation dual Xeon server as my lathe controller. I
> seem to recall that it was about 25k latency when I first got it, but
> I don't know what it does now with the newer kernels.
> 
> I know it needed the SMI tweak. But with that it never flags the
> real-time delay message, so I assume it's OK.
> 
> 
> -- 
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> If you can't fix it, you don't own it.
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Re: [Emc-users] PWMGEN in PDM mode and not PWM

[Karlsson & Wang]

PDM I am pretty sure should be fixed. Then number of pulses increase with 
increasing speed it may be the encoder signal?



On Mon, 09 Nov 2015 12:29:12 +
"Marius Liebenberg"  wrote:

> Hi All
> I have a pwmgen setup to take the spindle command to generate a pwm 
> signal. What I see on my scope is a PDM signal. I.E. the number of 
> pulses increase as I increase the speed. I nee it to be PWM.
> I tried type=0 and type=1 when I load. Is there naother setting that 
> does not get mentioned in "man"?
> 
> The reason for using another pwmgen is beacuse I have to set up manual 
> pulses for a spesified period. Not the usual spindle operation.
> 
> -
> Regards / Groete
> 
> Marius D. Liebenberg
> +27 82 698 3251
> +27 12 743 6064
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Re: [Emc-users] PWMGEN in PDM mode and not PWM

[Karlsson & Wang]

Stepper motor?


On Mon, 09 Nov 2015 12:29:12 +
"Marius Liebenberg"  wrote:

> Hi All
> I have a pwmgen setup to take the spindle command to generate a pwm 
> signal. What I see on my scope is a PDM signal. I.E. the number of 
> pulses increase as I increase the speed. I nee it to be PWM.
> I tried type=0 and type=1 when I load. Is there naother setting that 
> does not get mentioned in "man"?
> 
> The reason for using another pwmgen is beacuse I have to set up manual 
> pulses for a spesified period. Not the usual spindle operation.
> 
> -
> Regards / Groete
> 
> Marius D. Liebenberg
> +27 82 698 3251
> +27 12 743 6064
> --
> Presto, an open source distributed SQL query engine for big data, initially
> developed by Facebook, enables you to easily query your data on Hadoop in a 
> more interactive manner. Teradata is also now providing full enterprise
> support for Presto. Download a free open source copy now.
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Re: [Emc-users] could Linux cnc control of unconventional ... hydraulic

[Karlsson & Wang]

> 2015-11-09 8:49 GMT+02:00 Eric Keller :
> 
> > there were hydraulic milling machines sold based on Moog hydraulics
> > and Bridgeport iron.  I assume those two companies could screw things
> > up, but the world has moved on.  To move a long distance takes a lot
> > of power.  Small movements with a lot of force behind them are really
> > easy, that's why you see fatigue machines and other shorter stroke
> > machines with hydraulic servo.
> >
> > AFAIK the problem of hydraulic actuators is low efficiency. There should
> be a high pressure high rate pump to provide high velocity and force. But
> when the actuator doesn't move it all goes via baypass just heating the
> fluid. Probably adjustable pump could help but it gets more complicated
> (just a guess).
> 
> --
> Andrew

Low efficiency is certainly a broblem so unless there is other advantages it is 
never a point to use hydraulics for this purpose.


Nicklas Karlsson

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Re: [Emc-users] could Linux cnc control of unconventional ... hydraulic

[Karlsson & Wang]

On Sun, 8 Nov 2015 15:47:37 + (UTC)
richsh...@comcast.net wrote:

> I suggest looking at a hydraulic approach. It eliminates all of the drive 
> lash problems with the rigidity problems that follow. Ingersoll Rand built a 
> prototype mill similiar to what you are describing, you may find getting in 
> touch with them to be useful. However it goes, I see this adventure of yours 
> to be an important step in pushing the technology window. Have at it. 

Hydraulic, that seems interesting how does hydraulic compare to a ball screw 
then it come to back slash and accuracy?

Nicklas Karlsson

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Re: [Emc-users] could Linux cnc control of unconventional ... hydraulic

[Karlsson & Wang]

> On 8 November 2015 at 17:10, Karlsson & Wang
> <nicklas.karls...@karlssonwang.se> wrote:
> 
> > Hydraulic, that seems interesting how does hydraulic compare to a ball 
> > screw then it come to back slash and accuracy?
> 
> Accuracy is limited by the feedback device, I think.
> 
> Servohydraulic cylinders are a bit different to normal ones. They
> generally don't seal the piston particularly, but a Moog-valve
> controls the differential pressure across the piston and the servo
> action compensates for any leakage.

Servohydraulic cylinders have low friction instead of perfect sealing?

Nicklas Karlsson

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Re: [Emc-users] could Linux cnc control of unconventional ... hydraulic

[Karlsson & Wang]

> On 8 November 2015 at 18:26, Karlsson & Wang
> <nicklas.karls...@karlssonwang.se> wrote:
> 
> > Servohydraulic cylinders have low friction instead of perfect sealing?
> 
> The ones I have worked with, yes.
> 
> I was at the high-force high-accuracy end, though. 250kN 100mm stroke,
> 0.001mm resolution. (Schenck tensile tester)

I suspect if a valve is used an motor running dynamic response could be good, 
do you know if it had good dynamic performance.

Nicklas Karlsson

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[Emc-users] Linuxcnc pre installed, (imrovments --> copyright)

[Karlsson & Wang]

They got the code for free and now they must share improvements for free. 

If a pre installed version of linuxcnc is found somewhere we should not forget 
the most important to check if they added someting useful. 




Nicklas Karlsson

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Re: [Emc-users] OT - Newsgroup email

[Karlsson & Wang]

For me it is normal to get my own emails back on this list on gEDA however it 
is the opposite.

Nicklas Karlsson

>Is it normal to NOT get your own emails back when posting to this 
> list?  My settings on the mailserver have "Receive your own post to the 
> list?" set to "Yes"
> 
>  I'm subscribed to over a dozen lists, and this is the only one that 
> it doesn't work on.
> 
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> Eagle3D - Created by Matthias Weißer
> github.com/mcason/Eagle3D
> 
> 
> 
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Re: [Emc-users] Desktops and OS's (Simplest possible)

[Karlsson & Wang]

The basic needs should be: Kernel with real time scheduler, X11 server for 
display unless it is run remotely, linuxcnc. I guess some more would be needed 
to get it started but not very much.

Usually there are plenty of space on harddrive so any ordinary distrubution 
could be used with out any real drawback. Only reason I could find to use 
simplest possible would be for cheap mass produced devices.

I have however discovered an STM32F407 ran a control loop perfectly with a 
frequency of 40kHz with around 30% CPU load but with an old ordinary higher 
clock frequency computer I can't run at 1kHz reliable. Modern GOOD for real 
time system micro controllers usually have nested interrupt controller with 
priority but I do not know if this is possible on an ordinary computer.

I guess effort could be best spent on kernel and in particular possibility to 
reduce priority of interrupts for ordinary tasks like disk I/O, graphics, other 
non real time I/O or non real time interrupts. Then clock cycles at "high" 
priority are free to use for real time tasks I expect good real time 
performance will come almost by itself.


Nicklas Karlsson



> Way back at the start of this email, someone was talking about different
> DEs. I personally have been running Bodhi linux, an Ubuntu derived distro,
> for a few years. The lead Dev recently posted a blog about installing
> moksha, an Enlightenment derivative, on Debian Jessie. Enlightenment does
> things differently, but, it is quite light on resources. I believe
> something like lxde is comparable.
> 
> On Wed, Nov 4, 2015 at 10:02 PM, Todd Zuercher 
> wrote:
> 
> > I've been running quite large carving and engraving g-code files directly
> > off a NAS share for quite some time without many problems (before that it
> > was on a Novel server, that was a little more problematic).  The only
> > problems were usually caused by major network glitches that often resulted
> > in taking down the whole Linuxcnc client (but I can't say that has happened
> > since switching to the NAS share).
> >
> > - Original Message -
> > From: "Dave Cole" 
> > To: emc-users@lists.sourceforge.net
> > Sent: Wednesday, November 4, 2015 12:10:26 PM
> > Subject: Re: [Emc-users] Desktops and OS's
> >
> > Second try...  I think that my Avast Antivirus is battling with Gmail's
> > security certificates and I lost :-( .
> >
> > Do you run the Gcode file off the NAS server directly or do you copy the
> > file to the local machine.
> > I thought there was a problem doing that reliably with LinuxCNC.
> > Something to do with network latency when reading the file which would
> > cause LinuxCNC to fault.
> >
> > Dave
> >
> >
> > On 11/4/2015 8:35 AM, Jim Craig wrote:
> > > I have a raid NAS that I send all of my gcode to. Then I open it
> > > directly from the NAS into LinuxCNC. Then I don't have to worry about
> > > what machine has the latest code etc. The latest is always on the NAS.
> > > And it it is backed up.
> > >
> > > I am going to have to see if I can get my machine computer to print to
> > > my network printer. That will be nice. Have not been able to get it to
> > > work so far.
> > >
> > > Thanks for the tips.
> > >
> > > Jim
> > >
> > > On 11/4/2015 7:27 AM, John Thornton wrote:
> > >> If he is doing that from a Windoze computer you can configure the right
> > >> click Send To for each machine so it's a one click op to send the file.
> > >>
> > >> JT
> > >>
> > >> On 11/4/2015 7:16 AM, Rick Lair wrote:
> > >>> It was an absolute requirement that I got that to work, probably like
> > >>> yours, we now have multiple machines in the shop running Linuxcnc, and
> > >>> thumb drives are easy to lose, so I have all the machines networked
> > >>> together, so the guy in the office that makes the programs, can drop
> > the
> > >>> finished g code program right into the nc_files folder in the
> > respective
> > >>> machine, right from his desk.
> > >>>
> > >>>
> > >>> Rick
> > >>>
> > >>>
> > >>>
> > >>> On 11/4/2015 8:09 AM, John Thornton wrote:
> >  Sweet, and it works! What a PITA to have to do this just to get an OS
> > to
> >  do basic things. I'm still hoping someone will chime in that has
> > built a
> >  real time kernel for Linux Mint so I can try that.
> > 
> >  JT
> > 
> >  On 11/4/2015 6:55 AM, Rick Lair wrote:
> > > Now you should be able to right click on the the folder icon you want
> > > tot share, see the "Share" tab, and be able to click down through and
> > > setup folder sharing on your network for that respective folder,
> > >
> > >
> > >
> > > On 11/4/2015 7:51 AM, John Thornton wrote:
> > >> Hi Rick,
> > >>
> > >> I followed the directions for adding folder sharing to Thunar but
> > don't
> > >> see any difference. What is is supposed to do?
> > >>
> > >> JT
> > >>
> > >> On 11/3/2015 9:59 AM, Rick Lair wrote:
> > >>> John,
> > 

Re: [Emc-users] Looping and axis

[Karlsson & Wang]

I have done programming with compiled languages and parsed row by row then 
executing. A main advantage of a compiler is the errors captured before 
execution. A button to check syntax, maximum velocity and maximum acceleration 
would probably be good.

Nicklas Karlsson



> my bad,
> I thought Linuxcnc required preparsing the entire program,
> almost simulating the entire motion to know bounds checks,
> and to respect velocity and acceleration constraints,
> and the blending was calculated...
> all this before attempting any motion.
> 
> I thought that nothing else would happen until this step was completed.
> (and it couldnt be completed if the task was infinite...  by definition )
> 
> Thats good news that the problem is only the gui preview.
> thx
> TomP tjtr33

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Re: [Emc-users] linuxcnc-dev in Synaptic when using uspace (was Carousel Component)

[Karlsson & Wang]

I downloaded the source and then figured out which packages wher needed for 
compilation then running "configure" script.

Nicklas Karlsson



On Thu, 5 Nov 2015 14:30:36 -0500
Rick Lair  wrote:

> Not to get too far off topic on my original thread, just wondering what 
> I need to do to get linuxcnc-dev in the Synaptic Package manager. I am 
> running debian wheezy using 2.7-uspace, and need to be able to use 
> halcompile to modify the carousel component. Linuxcnc-dev is not in the 
> package manager, and I am not sure what I should insert for the deb to 
> facilitate this.
> 
> 
> 
> -- 
> 
> Thanks
> 
> 
> Rick Lair
> Superior Roll & Turning LLC
> 399 East Center Street
> Petersburg MI, 49270
> PH: 734-279-1831
> FAX: 734-279-1166
> www.superiorroll.com
> 
> 
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Re: [Emc-users] raid NAS

[Karlsson & Wang]

There are mirroring there two discs have the same content. There are raid with 
redundancy where one drive could be removed without loss of data, this 
configuration may also increase speed.

Raid in software is possible but if all drive are on the same cable they have 
to share the bsndwidth but if this is a problem at all I do not know. I have an 
old server with hardware raid and it feels very fast.

Nicklas Karlsson



> Just looking up raid NAS and it looks like there are several levels of 
> raid and NAS is a Network Attached Storage. Is there something special 
> about NAS or can you do that with any hard drive?
> 
> JT
> 
> On 11/4/2015 7:35 AM, Jim Craig wrote:
> > I have a raid NAS that I send all of my gcode to. Then I open it
> > directly from the NAS into LinuxCNC. Then I don't have to worry about
> > what machine has the latest code etc. The latest is always on the NAS.
> > And it it is backed up.
> 
> 
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Re: [Emc-users] Linux Mint

[Karlsson & Wang]

> I actually have no clue what real time kernel I want or what the 
> difference is between any of them. I would be using a 5i25 7ix6 combo.
> 
> Thanks
> JT

I think linuxcnc print something about if real time posix is used then 
starting. If you have one installed try it and see if it seems good enough.

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[Emc-users] Profibus (Request Diagnostics)

[Karlsson & Wang]

I send yesterday to developer list but message seems to have disappeared so I 
here on user list insted. I am trying to get a profibus IO module up and 
running. Plan is to add to Linuxcnc and there plenty of these kind of devices 
out there so it will almost certainly be useful.

Do anyone happen to have the raw message format from a trace or similar for 
request diagnostic?

Nicklas Karlsson

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Re: [Emc-users] Spindle Voltage?

[Karlsson & Wang]

It depends. For an asynchronous motor lower voltage will mean lower available 
torque although it is technically possible to get full torque up to there 208 
volt is needed for full power but only if the inverter deliver 208 volt at this 
point. For a synchronous permanent magnet motor voltage is needed to get the 
rpm up although it may be possible to weaken the magnetic field to get rpm up.

Nicklas Karlsson



On Tue, 3 Nov 2015 09:41:37 -0500 (EST)
"Todd  Zuercher"  wrote:

> I recently purchased an inexpensive router spindle off of ebay. It is rated 
> at 6kw and 380v 3ph. The old spindle I'm replacing was dual voltage and could 
> be wired Y or delta, for 200-240 or 380-460 (7HP). Stupid me I didn't think 
> to check the old VFD and it is only capible of low voltage (running 208 3ph). 
> 
> So my question, what are the repercussions of feeding this motor with only 
> 208 3ph? 
> 
> If the only problem is a loss of a percentage of power, but not more than 
> half, I can live with that. (It cost less than 1/3 the price of the 
> original.) 
> 
> -- 
> 
>  
> 
> Todd Zuercher 
> mailto:zuerc...@embarqmail.com 
> 
>  
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Re: [Emc-users] Spindle Voltage?

[Karlsson & Wang]

> On Tue, Nov 3, 2015, at 09:41 AM, Todd  Zuercher wrote:
> > I recently purchased an inexpensive router spindle off of ebay. It is rated 
> > at 6kw and 380v 3ph. The old spindle I'm replacing was dual voltage and 
> > could be wired Y or delta, for 200-240 or 380-460 (7HP). Stupid me I didn't 
> > think to check the old VFD and it is only capible of low voltage (running 
> > 208 3ph). 
> > 
> > So my question, what are the repercussions of feeding this motor with only 
> > 208 3ph? 
> > 
> > If the only problem is a loss of a percentage of power, but not more than 
> > half, I can live with that. (It cost less than 1/3 the price of the 
> > original.) 
> > 
> 
> If you keep the same voltage-to-frequency ratio and maximum current the motor 
> will be happy.
> But of course the speed will be lower.  For example, if it is designed for 
> 380V, 240Hz, 14,400RPM,
> the volts-per-hertz ratio is 380/244 = 1.5833.  If the VFD can only deliver 
> 208V, then you will be
> limited to 208/1.5833 = 131Hz, and the top speed will be 7860 RPM.  It will 
> still deliver rated torque
> at rated current, but since the speed is lower the kW will be lower - only 
> about 3.8kW.
> 
> You can run it at a lower voltage-to-frequency ratio, but you won't get the 
> same torque.  For example
> you could run it at 208V and 240Hz.  You would get a no-load speed of 
> 14,400RPM, but the torque-
> per-amp will be lower - you'll still only get 3.8kW.
> 
> 
> -- 
>   John Kasunich
>   jmkasun...@fastmail.fm

I agree. To keep voltage-to-frequency ratio up to the maximum voltage and then 
just increase frequency is probably the best.

The VFD may use space vector control instead of voltage-to-frequency ratio.

Did you double check if your motor is Delta connected and may be Y connected 
instead?


Nicklas Karlsson

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Re: [Emc-users] Spindle Voltage?

[Karlsson & Wang]

On Tue, 03 Nov 2015 08:54:32 -0600
Ed  wrote:

> On 11/03/2015 08:41 AM, Todd Zuercher wrote:
> > I recently purchased an inexpensive router spindle off of ebay. It is rated 
> > at 6kw and 380v 3ph. The old spindle I'm replacing was dual voltage and 
> > could be wired Y or delta, for 200-240 or 380-460 (7HP). Stupid me I didn't 
> > think to check the old VFD and it is only capible of low voltage (running 
> > 208 3ph).
> >
> > So my question, what are the repercussions of feeding this motor with only 
> > 208 3ph?
> >
> > If the only problem is a loss of a percentage of power, but not more than 
> > half, I can live with that. (It cost less than 1/3 the price of the 
> > original.)
> >
> I have been running a 480 V motor at 240 V for a while now on a manual 
> mill. At half the voltage you get  one fourth the power.
> 
> Ed.

A half voltage and same speed you get half power. At half speed and half 
voltage you however get one fourth the power.

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Re: [Emc-users] Optimum packing problem

[Karlsson & Wang]

> I wonder what the optimum packing is for a mixture of ER32, ER20, ER16
> and ER11 collets?
> 
> A square array of ER32 with interstitial ER16, then a separate array
> of ER20 with interstitial ER11?

I would guess guess best packing would be like bee wax in three drawers. 
http://theanswerisalwayspork.com/wp-content/uploads/2014/05/honey-harvest-10.jpg



Nicklas Karlsson

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Re: [Emc-users] Ethernet Hostmot2 (drop packets at init)

[Karlsson & Wang]

On Tue, 27 Oct 2015 20:31:54 -0500
Jeff Epler <jep...@unpythonic.net> wrote:

> On Mon, Oct 12, 2015 at 10:50:07AM +0200, Karlsson & Wang wrote:
> > Yes it works great! Do you think this should be part of standard behaviour?
> 
> I talked to Seb about this change and we are uncomfortable putting it in
> 2.7 since it is an unnecessary change for Mesa boards.
> 
> However, I've prepared a branch
> "(origin/)jepler/hm2-explicit-queue-write" which should be semantically
> the same as the patch I offered earlier in this thread, which *you*
> could merge to your own 2.7ish branch for your use and which I will
> merge to our master branch if your testing produces a positive result.
> 
> I reworked it slightly because the first version created *two* ways to
> gather up reads (explicit and implicit); the new version gets rid of the
> old implicit way.  I did not test it on real hardware, I only
> compile-tested it.
> 
> Jeff

Yes it is unnecessary change for Mesa boards but not the network. I am however 
very happy with a branch and will not complain.

If periodic real time communication is taking place while configuring a card 
either configuration packets must have lower  priority or dead lines may be 
missed.

In practice this may be a problem at startup with Meas boards if real time 
communication start before all connected boards have been configured.


Nicklas Karlsson

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Re: [Emc-users] [Emc-developers] Off topic question - Need help with remote cell phone data connection via site to site VPN

[Karlsson & Wang]

> ... They like to "control" the customer
> even when they don't know what they are doing.

I think an old sales person trick is to first check your "budget" or how much 
money you have available to spend then they find the most expensive you are 
likely to buy.

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Re: [Emc-users] Debian install from live image

[Karlsson & Wang]

> Since Lucid has reached end of support I decided to back up my config and
> install from the 2.7 live CD.
> Having done that, installed all of the updates, and adjustments to my
> config files,I ran the latency test.
> Overall the latency numbers are 30% higher than the Lucid install, but
> still in an acceptable range.
> Setting "isolcpus=1" in grub has no effect on latency, as it did in the
> Lucid install.
> Now when I run LinuxCNC, I am getting RTAPI error on startup
> intermittently.  When it does start without the error, the error shows up
> within 5 to 10 minutes.
> 
> Attached are the dmesg, and the -v startup for linuxcnc.
> 
> Watching the system monitor while LinuxCNC is running for spikes in the CPU
> utilization shows nothing unusual, other than the second cpu is not being
> utilized at all.
> I have always thought that isolating a cpu from the linux scheduler was to
> allow the RTAI kernel to use it without the system interrupts interfering
> with it.
> 
> Is there some setup that i missed to mask the RTAI kernel to use the
> isolated cpu? Or are there any "taskset" statements that need to be changed
> to properly utilize the isolated cpu?
> 
> I know just enough about real time OSes to be really dangerous!
> 
> Any help is always appreciated!
> 
> --J. Ray Mitchell Jr.
> jrmitche...@gmail.com
> (818)324-7573

If there are more than one core one serve the interrupts and the second is used 
for real time scheduling?

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Re: [Emc-users] help about I can't find the src file

[Karlsson & Wang]

I use 2.8 which are the latest available I have round and there is a file 
src/emc/kinematics/genhexkins.h for hexapod kinematics. I also have an hexapod 
out in garage but it is further down on my list of things to do.

Nicklas Karlsson



On Thu, 15 Oct 2015 17:07:05 +0800
"开心小八怪" <610013...@qq.com> wrote:

> Dear friends:
>I installed the live+dvd the version of LinuxCNC 2.6.4. I will make 
> use of it to control the parallel mechanism. So, I need the Hexapod/PKM 
> configuration. But I can't find the Hexapod in the Axis interface and the 
> file src which includes the movement function. Help me pleas! Can I make a 
> download about this configurations? I need your help. Thanks
> 
> 
> Yours
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Re: [Emc-users] Rookie question - what to get to run LinCNC easily/inexpensively

[Karlsson & Wang]

> ...
> Have you guys found anything in particular that might cause latency spikes
> that I'm seeing? I installed 2.7-Wheezy from the pre-built live/install ISO
> and I'm using the onboard video. No extra hardware besides a USB mouse and
> keyboard.
> Also, I'm planning to get a Mesa 5i25 so maybe the latency isn't a problem?
> 
> regards,
> - Claude

I have been thinking about moving the control loop from the PC to the motor 
driver and then latency would be less of a problem. The motor driver I use run 
a control loop at 40kHz while linuxcnc position control loop run at 1kHz but 
with position control in motor driver and linear interpolation I guess 100Hz 
for linuxcnc control loop would be enough.

Nicklas Karlsson

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Re: [Emc-users] Ethernet Hostmot2 (drop packets at init)

[Karlsson & Wang]

Yes it works great! Do you think this should be part of standard behaviour?

I would suggest to limit the number of sent messages and ideally used bandwidth 
at startup to the same as used during normal operation. I also feel I have to 
spend a few hour to help with this if needed.

In a perfect world and at a first glance it would be good to send the 
configuration data as fast as possible. But I guess it would be a good idea to 
limit sending of messages to the same used then running normally to avoid a 
surge in needed bandwidth at startup and it will also limit the receiving 
capacity to the same as during normal running?


Regards Nicklas Karlsson




On Sun, 20 Sep 2015 17:30:32 -0500
Jeff Epler  wrote:

> I put together this patch which reduces the number of consecutive write
> packets sent at startup.  In my testing system it reduced it from 22 to
> 2.  However, I only spent about 2 minutes testing it, just a handful of
> startups.
> 
> -- >8 -- 
> >From 5bf2780aff4b4af183ec54f1fbcd3f0a3b0408c7 Mon Sep 17 00:00:00 2001
> From: Jeff Epler 
> Date: Sun, 20 Sep 2015 15:28:30 -0500
> Subject: [PATCH] WIP hm2_eth: batch writes from hm2_force_write
> 
> ---
>  src/hal/drivers/mesa-hostmot2/hm2_eth.c   |2 +-
>  src/hal/drivers/mesa-hostmot2/hostmot2-lowlevel.h |2 ++
>  src/hal/drivers/mesa-hostmot2/hostmot2.c  |4 
>  3 files changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/src/hal/drivers/mesa-hostmot2/hm2_eth.c 
> b/src/hal/drivers/mesa-hostmot2/hm2_eth.c
> index e57f14e..b1a3e80 100644
> --- a/src/hal/drivers/mesa-hostmot2/hm2_eth.c
> +++ b/src/hal/drivers/mesa-hostmot2/hm2_eth.c
> @@ -523,7 +523,7 @@ static int hm2_eth_enqueue_read(hm2_lowlevel_io_t *this, 
> rtapi_u32 addr, void *b
>  static int hm2_eth_enqueue_write(hm2_lowlevel_io_t *this, rtapi_u32 addr, 
> void *buffer, int size);
>  
>  static int hm2_eth_write(hm2_lowlevel_io_t *this, rtapi_u32 addr, void 
> *buffer, int size) {
> -if(rtapi_task_self() >= 0)
> +if(rtapi_task_self() >= 0 || this->queue_writes)
>  return hm2_eth_enqueue_write(this, addr, buffer, size);
>  
>  int send;
> diff --git a/src/hal/drivers/mesa-hostmot2/hostmot2-lowlevel.h 
> b/src/hal/drivers/mesa-hostmot2/hostmot2-lowlevel.h
> index 3df443c..81e40fd 100644
> --- a/src/hal/drivers/mesa-hostmot2/hostmot2-lowlevel.h
> +++ b/src/hal/drivers/mesa-hostmot2/hostmot2-lowlevel.h
> @@ -144,6 +144,8 @@ struct hm2_lowlevel_io_struct {
>  // if TRUE, the hostmot2 driver will export those three functions and 
> also read_gpio() and write_gpio()
>  int threadsafe;
>  
> +// if TRUE, queue writes for a subsequent call to ->send_queued_writes()
> +int queue_writes;
>  void *private;  // for the low-level driver to hang their struct on
>  };
>  
> diff --git a/src/hal/drivers/mesa-hostmot2/hostmot2.c 
> b/src/hal/drivers/mesa-hostmot2/hostmot2.c
> index 3acb34d..57365a8 100644
> --- a/src/hal/drivers/mesa-hostmot2/hostmot2.c
> +++ b/src/hal/drivers/mesa-hostmot2/hostmot2.c
> @@ -1655,6 +1655,7 @@ void rtapi_app_exit(void) {
>  
>  // this pushes our idea of what things are like into the FPGA's poor little 
> mind
>  void hm2_force_write(hostmot2_t *hm2) {
> +hm2->llio->queue_writes = 1;
>  hm2_watchdog_force_write(hm2);
>  hm2_ioport_force_write(hm2);
>  hm2_encoder_force_write(hm2);
> @@ -1664,5 +1665,8 @@ void hm2_force_write(hostmot2_t *hm2) {
>  hm2_sserial_force_write(hm2);
>  hm2_bspi_force_write(hm2);
>  hm2_dpll_force_write(hm2);
> +
> +hm2->llio->queue_writes = 0;
> +if(hm2->llio->send_queued_writes) 
> hm2->llio->send_queued_writes(hm2->llio);
>  }
>  
> -- 
> 1.7.10.4
> 
> 
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Re: [Emc-users] Hostmot2 (Use two cards)

[Karlsson & Wang]

Now it works, there where a few other issues to in particular the two devices 
had the same MAC adress.

I actually need to have two rows:
loadrt hostmot2
loadrt hm2_eth ... similar as your row below


Regards Nicklas Karlsson




> The "waitpid" error is a very generic error that indicates some
> sub-program has failed.  So look for other messages that give a more
> specific indication of the problem.
> 
> Here is a loadrt line I used when I was testing 3 hostmot2 ethernet
> boards:
> 
> loadrt hm2_eth config="num_encoders=1 num_pwmgens=1 num_stepgens=1 
> enable_raw=1,enable_raw=1" board_ip=192.168.1.123,192.168.1.122,192.168.1.121
> 
> To see which config goes with which board-ip, just look for the commas
> and match up the strings
> 192.168.1.123 num_encoders=1 num_pwmgens=1 num_stepgens=1 enable_raw=1
> 192.168.1.122 enable_raw=1
> 192.168.1.121 [defaults]
> 
> You would only 'loadrt' hm2_eth once, even for multiple cards.  If you
> have two separate loadrt lines, it's definitely not going to work.
> 
> Check that each card works individually.  Remember that you have to
> configure them manually to have distinct IP addresses.
> 
> If you are still encountering trouble, show us your whole hal file and
> the whole output that occurs when trying to start linuxcnc from a
> terminal.
> 
> Jeff
> 
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[Emc-users] Hostmot2 (Use two cards)

[Karlsson & Wang]

I am trying to use two ethernet cards at the same time with the hostmot2 driver 
but get an error message "waitpid failed". I suspect this is because I try to 
load the low level driver twice, do anybody have an idea if this might be the 
case?

Regards Nicklas Karlsson

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Re: [Emc-users] AC Servo Motors

[Karlsson & Wang]

> Apparently DC Brushless cog but not AC ? 
> Anyway I'm about to order a 6N.m 1.8KW AC motor and drive for $340.  It's
> worth a try.
> 
> Brushes ?? My South Western Industries mill has run 20+ hours a week for + 10
> years and I have never changed a brush. Maybe I should check sometime. 
> 
> Possibly if the motors are under powered, they need changing more often. I
> changed my first set of cordless drill brushes a month ago.  

It could also be the sales person selling the AC motors talking about the 
brushes. I saw machine for sale a while ago, "never used since bought from 
seller".

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Re: [Emc-users] Hostmot2 drivers

[Karlsson & Wang]

> I am rebuilding a box with xubuntu 10.04 and the linuxcnc 2.5.4 install
> script. I ran into a similar problem last April that Sebastian walked me
> through. Rechecking those posts, the problem is a little different. While
> linuxcnc installed fine, I do not see the hostmot2 drivers in synaptic. I
> added:
> 
> deb http://buildbot.linuxcnc.org/hm2 hm2-firmware v0
> ...
> To sources.list and reloaded, but they are still not coming up.
> ...
> Any idea what I am doing wrong?

No but I use the hostmot2 drivers and compiled them myself. I think I had to 
add some missing dependencies.

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Re: [Emc-users] Yaskawa or not

[Karlsson & Wang]

> ...  And chances are that if you do the conversion, they will call 
> you when a drive goes down in the future.
> 
> Dave

Could rotate the motor with a drill or similar and measure the voltages with an 
oscilloscope?

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Re: [Emc-users] multiple gcode streams in parallel

[Karlsson & Wang]

> ..
> What would be useful in such a setup is an ability to pass information 
> directly from one LCNC host to another to coordinate functions such as 
> transferring a pallet with work on it to another machine for additional 
> operations.
> 
> One example would be two machines doing an operation that takes 30 
> minutes, both feeding to a 3rd machine doing an operation that takes 
> less than 30 minutes. With all three communicating, the 3rd machine 
> could report when it's free and whichever feeder is farthest along on 
> its job would be prioritized to transfer its pallet next.

General purpose IO, M62 to M65 turn on a digital output and M66 wait on input. 
I guess a synchonization primitive might be useful so that two controllers wait 
until both of them have reached the same numbered synchronization point.

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Re: [Emc-users] multiple gcode streams in parallel

[Karlsson & Wang]

> ...
> I now need to extend it to run two separate robots off the same linuxcnc
> controller and receiver program. This brought up a question about the
> python interface.

Add an extra axis ?

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Re: [Emc-users] A lot of input/output. Cheap

[Karlsson & Wang]

> I've owned this machine quite a while, I know how it works. I'm not new in
> the plastics arena as I started moulding in the early 90's.
> This particular machine is made for vertical moulding, I can flip it as it
> is. It takes me 15 minutes to re-arrange the setup for verticals and it
> runs perfect that way too. On a vertical you simply slide the moulds into
> place. I prefer that instead of craning any given day. We're not talking 60
> ton or above. This is a 35 ton machine so the moulds aren't really that
> heavy.
> 
> A slow PC with LinuxCNC and an Arduino board is way cheaper than any PLC
> ECU. If I retrofit this lump _it_will_be_ LCNC. But at the moment I am more
> into ripping it up and save some of the parts for a home brew.

I am new to linuxcnc and are just starting to get my first machine running. Are 
there any suitable user inteface for an injection molding machine? These kind 
of ordinary robot arms?

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Re: [Emc-users] Porting LinuxCNC(EMC) to Windows was CAD/CAM for LinuxCNC

[Karlsson & Wang]

> The machine hardware needs to be smart enough to monitor for 
> communication failures. There should be full duplex communication so 
> that every command either way is answered by an ACK. No response, it 
> shuts down.

Real time data is usually sent periodically and in such other solutions are 
possible. If the receiver know then data should arrive it may turn off if not 
received, this is simple solution that work almost like an ordinary cable 
although with a longer delay. Usually there is data sent back periodically the 
other way and this could be used instead of an ack.

If you send data then changed and use an ack instead of periodic data you 
almost certainly end up using less bandwidth except then needed the most!

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Re: [Emc-users] R: A lot of input/output. Cheap

[Karlsson & Wang]

> Hi Sven.
> It is a small machine but in any case I suggest to you to use a plc in stead 
> on LCNC.
> I mean it is possibile to do it even with LCNC but will be much difficult.
> I did many injection  molding machine retrofit (the electric and Electronic 
> and software part) and a plc+hmi is the much confortable solution.
> Realtime is needed as per machine cycle control (you have to be deterministic 
> for a precise and reliable control).
> A 10ms task can be acceptable.
> I personally made a hw and sw package with Schneider Electric plc M258 and 
> hmi Magelis GTO 10"" touch screen plus a software Application that I 
> personally developed.
> But if you have time to spend and less money you cam try LCNC + MODBUS IO . 
> ;-)

I would say HMIs are quite exensive comparted to slightly outdated PC, what do 
you say about that?

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Re: [Emc-users] Need a computer (LinuxCNC & Mesa) Advice

[Karlsson & Wang]

> If it is for professional use, I would not get a refurb unit. Why take
> someone else's problem for a few bucks. For the mini(itx,atx) systems,
> cooling is the biggest issue. They tend to often focus on home media apps,
> and they want the lowest sound, which means poor thermal management. I's
> the same reason you don't use a laptop in a server situation, no matter how
> cheap it is. Depending on the mounting, either small towers or small 1U
> rack mount chassis do the best, IMO.

According to my experience old servers or other large computer often could be 
bought cheap.

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Re: [Emc-users] R: R: A lot of input/output. Cheap

[Karlsson & Wang]

> If you would like a 'personal" usage machine you can try what ever Solution 
> should work.
> But if you are searching For a reliable industrial grade Solution you have to 
> spend some Money. This is my experience on that specific argument. Sometimes 
> cheap is not good. ;-)

This is also my view and that is why it could be better to buy old industrial 
machine instead of a brand new hobby machine. But if a few year old computer is 
good enough it so cheap I take the risc to replace it later.

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Re: [Emc-users] A lot of input/output. Cheap

[Karlsson & Wang]

> > Hi Sven.
> > Can you send a picture of the machine you have to retrofit ?
> > Is it an injection moulding machine ?
> > If yes how many tons is the closing clamp force and how many heating zones
> > have the injection barrel/chamber ?
> >
> > Regards.
> >
> > Alex
> >
> > Here you go.
> https://c2.staticflickr.com/6/5652/20606563013_d2a911f7e7_b.jpg
> 
> It's a really nice machine, a Stübbe that has been running extremely fine
> moulds. I can even rotate the moulding line to vertical position. I am
> actually thinking of ripping the machine a part and make a new base with
> the clamps fixed in vertical position to save space.

I also have an old injection mould machine I plan to retrofit. But I also have 
other problems power supply is limited so fuses will before correct pressure is 
reached.

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Re: [Emc-users] Off topic. Open CV and Newts

[Karlsson & Wang]

Opencv http://opencv.org/ is the one i heard about. I am currently unemployed 
but have no experience with this, if not paid I am also busy with other things.



On Tue, 22 Sep 2015 15:12:22 +0100
andy pugh  wrote:

> A friend is a professional newt-spotter. He is an ecologist who has a
> lot of dealings with the Great Crested Newt, a protected species.
> Part of his work involves identifying individual newts by their
> distinctive orange and black belly markings. He has several hundred
> photos to check to figure out which ones are of the same newt.
> 
> It seems to me that this would be a good application for machine
> vision. Can anyone give pointers to a way to get up and running
> quickly with this?
> 
> -- 
> atp
> If you can't fix it, you don't own it.
> http://www.ifixit.com/Manifesto
> 
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Re: [Emc-users] A lot of input/output. Cheap (Profibus)

[Karlsson & Wang]

> > > I think your suggestion with the HAL/Arduino library will be the cheapest
> > > possible and more than good for this application, I will try it for sure!
> > > With some small tweaks it will be fine for a Mega board and I should have
> > > enough I/O.
> > > Thanks!
> > >
> > > /S

Profibus have a very common protocol for a long time, sometimes there are cheap 
used IO modules available for sale and this is real professional stuff. 
Currently however there is no support for profibus in linuxcnc but I have been 
working on profibus for a short and plan to add it at soon as there is enough 
time. Hopefully it will be soon I just had to learn Chinese and spent arund 
three months on it the last year.

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Re: [Emc-users] A lot of input/output. Cheap (Profibus)

[Karlsson & Wang]

> Gentlemen,
> be careful with Profibus, there are different tastes of it. Especially 
> the one designed for building automation will not very well suit our 
> needs. But, certainly, this is highly professional technology, extremely 
> noise proof even at long distances of several hundred meters.
> Peter

I heard about DP and PA. I will implement the one used for Siements ET 200L-SC. 
I read somewhere about patent problems if implementing this kind of protocol 
but have also read something about an EU directive regarding software 
interoperability, anybode who know something?

Regards Nicklas Karlsson

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Re: [Emc-users] A lot of input/output. Cheap (Profibus)

[Karlsson & Wang]

> I have used a lot of Profibus devices. I used to work for Siemens.
> Profibus is very robust if installed properly.DP is the norm for 
> remote I/O.
> PA is designed for the process industry and not nearly as common.
> 
> I always thought that a chip was needed for a DP master.I don't 
> think a DP master device can be made via software and standard RS485 
> interface, but I could be wrong.

I also read about a chip but have not found any hardware constraints, Ethecat 
for example insert information into the packet while it pass thru the device 
which put very high constraints on the timing.

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Re: [Emc-users] Ethernet Hostmot2 (drop packets at init)

[Karlsson & Wang]

> > I am using the hostmot2 driver with ethernet and sometimes startup does not 
> > work properly. Then investegating further with wireshark I found that some 
> > packets seems to not be received correctly. I also found time between 
> > packages are very small at startup because they are sent as fast as the 
> > computer while during operation there is a fixed time between packets.
> >
> > Have anyone else had similar problems?
> 
> 
> Are you running 2.7.0?
> 
> Jeff Epler fixed some random startup issues with hm2_eth fairly recently
> these are fixed in the released version 2.7.0
> 
> 
> Also if this is with your remote hardware (not Mesa FPGA hardware), there may 
> be possible data loss with all the write only initialization data sent at 
> startup with no checking for possible buffer overflows. This is pretty well 
> masked with our hardware since its pretty fast and has a 12K byte receive 
> packet buffer in the Ethernet chip.

My remote hardware had problem and then increasing the buffer size problem 
decreased considerably. Wireshark show 12 packets in a row with around 7µs 
between each in average. I am pretty sure it have happened in the direction to 
but not totally. It is not a big problem since only happens during startup then 
quite many packets are sent in a row for configuration during normal running 
packets are only sent with servo thread period.

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[Emc-users] Ethernet Hostmot2 (drop packets at init)

[Karlsson & Wang]

I am using the hostmot2 driver with ethernet and sometimes startup does not 
work properly. Then investegating further with wireshark I found that some 
packets seems to not be received correctly. I also found time between packages 
are very small at startup because they are sent as fast as the computer while 
during operation there is a fixed time between packets.

Have anyone else had similar problems?

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Re: [Emc-users] CAD/CAM for LinuxCNC

[Karlsson & Wang]

> > So with MACH3 turning into a networked licensed (must be internet
> > connected)

The machine will not start without an internet connection ?

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Re: [Emc-users] Cheap servos

[Karlsson & Wang]

How about usig a linear position sensor?



On Thu, 3 Sep 2015 11:14:22 +0100
andy pugh  wrote:

> I wonder if these motor/drive combinations would work in a CNC application?
> http://www.ebay.co.uk/itm/141744001054
> 
> I imagine that they run trapezoidal commutation and have no encoders,
> but that isn't an insurmountable issue.
> 
> -- 
> atp
> If you can't fix it, you don't own it.
> http://www.ifixit.com/Manifesto
> 
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Re: [Emc-users] It looks like my encoder noise reducing filter is too laggy

[Karlsson & Wang]

By limiting the signal I guess you get "wind-up" in the integrator of the PID 
controller. I think there is a maximum acceleration option in the *ini which is 
better suited to limit acceleration.


On Tue, 1 Sep 2015 15:12:05 -0400
Gene Heskett  wrote:

> Thinking that a direct motor reverse is a bit brutal on both the motor, 
> and probably explores the current limit facility built in the Pico pwm 
> servo amp, I tried adding a limit3 between the signal from 
> motion.spindle-speed and the input to pid.s.command, which was formerly 
> a direct net in the .hal file.
> 
> Without it, a spindle reversal from 1000 rpms is accomplished in just a 
> fraction of a second.
> 
> But while it did slow down the turn around of the spindle, I am getting a 
> huge overspeed in the new direction until it settles back to the 
> commanded rpms.  Not at all usable IMO when the spindle may be turning 
> 350 revs driving a 4-40 tap in a G33.1 cycle, and the reversal runs the 
> spindle up to 2850 revs.  The head keeps up, but still it looks 
> dangerous to me.  It literally goes wide open and jerks the tap out of 
> the hole, in perfect synch, beautiful threads.  A larger tap would be 
> self cleaning by spinning itself clean.  Now theres a grin causing 
> thought. :)
> 
> One of the things I did in hacking up this filter, basically a 4 stage 
> shift register with all 4 stages feeding a triplet of sum2's, with a 
> weighting scale factor of .2500 so basically the final sum2's output is 
> the updated average of the last 4 encoder transitions, unforch this 
> results in single value being clocked thru the sample_holds by the 
> servo-threads repetition cycle when the spindle is turning slow enough 
> that we get the same reading several times in between transitions.
> 
> Thats pretty slow as the encoder disk has 268 edges per revolution.  So 
> at low speeds, the filter degenerates into whatever the last edge 
> transition set into the 5i25's registers by clocking that value all the 
> way thru the shift registers the S_H's are in about 5 milliseconds.  So 
> I made a hold signal out of a comparison between the encoder out and the 
> S_H's first stage out. But, and this is what I think is actually biting 
> me, the encoder and the S_H's have to have a conv_float_to_s32 and vice 
> versa wrapped around them. 
> 
> So I may as well just go ahead and either junk the whole idea, or figure 
> out something that does not need all the float to s32 and vice versa.
> 
> Sample_hold is s32 except bit "hold", and the man page doesn't even say 
> what state is hold & what state is fall-thru.
> 
> comp is float, incompatible with the S_H
> 
> Sum2 is float, incompatible with the S_H
> 
> So the processing chain is too long and likely in the wrong addf 
> sequence.  But it would be a huge help if we had a float version of the 
> sample_hold.
> 
> Any chance of that ever happening?
> 
> I'll test the theory that the filter delay is the culprit by bypassing 
> the filter.
> 
> Another possibility is that at the instant of polarity reversal going 
> into the .command port of pid.s, a reset signal could be slammed into 
> the pid.s to cancel any effects of the spindles overshoots in the wrong 
> direction, the lack of which is causing a windup in the pid. Halscope 
> should be able to show me that I would think.  But how to generate that, 
> I haven't a clue, but that almost HAS to be the cause of the 
> windup/catchup.
> 
> A 2nd question then, pid.s.error-previous-target, bit in, should be what 
> for a velocity loop such as a spindle?  Currently set true, by pncconf & 
> I haven't touched it.
> 
> Anybody else got a better idea?
> 
> Thanks all.
> 
> Cheers, Gene Heskett
> -- 
> "There are four boxes to be used in defense of liberty:
>  soap, ballot, jury, and ammo. Please use in that order."
> -Ed Howdershelt (Author)
> Genes Web page 
> 
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Re: [Emc-users] computing max acceleration for an actuator

[Karlsson Wang]

I also suspect max acceleration will be a little bit lower for higher speed 
since motor back-emf will limit available voltage for acceleration.


On Fri, 28 Aug 2015 01:47:23 +
Kyle Kerr ker...@gmail.com wrote:

 Late to the party armed with nothing more than book smarts, may not be
 enough.
 If you can accurately measure time over distance, you should be able to
 find relatively close max accel. Once the time over distance is constant
 from point to point you go back and say 0 to 100 took 500mS and 14mm or
 whatever. Then you just do the math to find acceleration.
 
 On Thu, Aug 27, 2015, 6:47 PM Dave Cole linuxcncro...@gmail.com wrote:
 
  If you set the max acceleration lower than
  the actuator is capable of, I assume it will work fine and just take longer
  to ramp up to full speed than it could in theory.
 
  Yes.   It will work fine.  You want the accel limit lower than less that
  what it can actually do.  Years after you set this up and things get a
  little gummed up,
  you don't want your actuator to be slower than what you command.   That
  may result in following errors and frustration.
 
  The same is true of the max velocity.
 
  Dave
 
 
 
  On 8/27/2015 6:15 PM, Jerry Scharf wrote:
   My question was the opposite. If you set the max acceleration lower than
   the actuator is capable of, I assume it will work fine and just take
  longer
   to ramp up to full speed than it could in theory.
  
   jerry
  
   On Thu, Aug 27, 2015 at 1:50 PM, Karlsson  Wang 
   nicklas.karls...@karlssonwang.se wrote:
  
   If you try to accelerate the actuator above what the actuator is capable
   of the best thing that could happen is it will not keep track of the
   position and the other thing are more bad.
  
  
  
  
   On Thu, 27 Aug 2015 11:35:04 -0700
   Jerry Scharf jsch...@finsix.com wrote:
  
   Hi,
  
   One last question about this. Is there any harm in reducing the max
   acceleration below what the actuator is capable of? I wouldn't seem
  like
   it, but I want to be sure.
  
   I know it will slow things down a bit, but this is by far the fastest
   part
   of my system and only moving a short distance.
  
   jerry
  
  
   On Tue, Aug 25, 2015 at 5:04 PM, TJoseph Powderly tjt...@gmail.com
   wrote:
   Jerry I didnt answer your question.
   to measure acceleration there's an industry standard 'step' test.
   The 'step' is to apply the voltage required to achieve max velocity.
   This voltage **instantly** rises from 0 to the value needed for max
   velocity.
   Thats where the name 'step' comes from,
   Its a square edge on a scope.
  
   A second measurement is now needed,
   Some way to determine _when_ the
   maximum velocity is actually achieved.
  
   Old school dc motors gave us Tachos so this was easy.
   I dont know what you can put together.
   You could attach a voice coil to the end, I suppose.
   Measure when the output voltage goes constant ( at max vel )
   A scope should show a 'knee' starting at 0Volts.
  
   But if you measure time from the 'step' until the max vel,
   you have the precise acceleration _time_.
  
   The acceleration time divide by time is the acceleration
  
   ( example  .240 Sec accel time to achieve 800mm/minute velocity
   is .24 sec to achieve 13.333mm/sec
   is 55.555 mm/s/s
  
  3.15/sec  / 0.02ec = 157.5in/s/s )
  
   HTH
   TomP
   tjtr33
   On 08/25/2015 04:09 PM, Jerry Scharf wrote:
   Hi,
  
   My quick scan of the docs didn't find an explanation for how to
   calculate
   this from manufacturer specs rather than experimentation. I want to
   make
   sure I am doing this right.
  
   The actuator is rated a 3.15 inches per second and it can reach full
   speed
   in under .02s for the load I will be putting on it. If I use a = v/t,
   this
   comes out to about 150 inches per second square. Does this look
   right?
   The actuator is a SMC LXPB2BD-50S that I picked up used.
  
   jerry
  
  
  
  
  
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Re: [Emc-users] computing max acceleration for an actuator

[Karlsson Wang]

If you try to accelerate the actuator above what the actuator is capable of the 
best thing that could happen is it will not keep track of the position and the 
other thing are more bad.




On Thu, 27 Aug 2015 11:35:04 -0700
Jerry Scharf jsch...@finsix.com wrote:

 Hi,
 
 One last question about this. Is there any harm in reducing the max
 acceleration below what the actuator is capable of? I wouldn't seem like
 it, but I want to be sure.
 
 I know it will slow things down a bit, but this is by far the fastest part
 of my system and only moving a short distance.
 
 jerry
 
 
 On Tue, Aug 25, 2015 at 5:04 PM, TJoseph Powderly tjt...@gmail.com wrote:
 
  Jerry I didnt answer your question.
  to measure acceleration there's an industry standard 'step' test.
  The 'step' is to apply the voltage required to achieve max velocity.
  This voltage **instantly** rises from 0 to the value needed for max
  velocity.
  Thats where the name 'step' comes from,
  Its a square edge on a scope.
 
  A second measurement is now needed,
  Some way to determine _when_ the
  maximum velocity is actually achieved.
 
  Old school dc motors gave us Tachos so this was easy.
  I dont know what you can put together.
  You could attach a voice coil to the end, I suppose.
  Measure when the output voltage goes constant ( at max vel )
  A scope should show a 'knee' starting at 0Volts.
 
  But if you measure time from the 'step' until the max vel,
  you have the precise acceleration _time_.
 
  The acceleration time divide by time is the acceleration
 
  ( example  .240 Sec accel time to achieve 800mm/minute velocity
 is .24 sec to achieve 13.333mm/sec
 is 55.555 mm/s/s
 
3.15/sec  / 0.02ec = 157.5in/s/s )
 
  HTH
  TomP
  tjtr33
  On 08/25/2015 04:09 PM, Jerry Scharf wrote:
   Hi,
  
   My quick scan of the docs didn't find an explanation for how to calculate
   this from manufacturer specs rather than experimentation. I want to make
   sure I am doing this right.
  
   The actuator is rated a 3.15 inches per second and it can reach full
  speed
   in under .02s for the load I will be putting on it. If I use a = v/t,
  this
   comes out to about 150 inches per second square. Does this look right?
  
   The actuator is a SMC LXPB2BD-50S that I picked up used.
  
   jerry
  
 
 
 
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Re: [Emc-users] Max spindle PWM frequency

[Karlsson Wang]

It is implemented by a counter so then frequency is increased resolution go 
down. Som micro controllers have high resolution timers which get resolution 
equal to a counter at about a few giga hertz although I get the impression the 
extra high resolution is implemented a little bit different.

On Tue, 25 Aug 2015 09:16:02 +
Marius Liebenberg mar...@mastercut.co.za wrote:

 I am trying to generate a pwm signal to drive a laser power source using 
 the spindle pwmgen. The minimum frequency must be 20khz. I read in the 
 manual that pwmgen is not good on higher frequency. The question is will 
 it reach 20khz or must I rather try using a stepgen?
 
 
 
 -
 Regards / Groete
 
 Marius D. Liebenberg
 +27 82 698 3251
 +27 12 743 6064
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Re: [Emc-users] Max spindle PWM frequency

[Karlsson Wang]

The micro controllers STM334 or XMC4xxx have high resolution timers equal to a 
frequency of up to a few gigz hertz.



On Tue, 25 Aug 2015 09:43:38 +
Marius Liebenberg mar...@mastercut.co.za wrote:

   Yes I though as much. I am running at 15us at the moment. I am thinking 
 to use a MCU or a small FPGA to read the low frequency PWM and then 
 translate that to a 40khz PWM signal.
 
 
 On 25 August 2015 at 10:16, Marius Liebenberg mar...@mastercut.co.za 
 wrote:
   I am trying to generate a pwm signal to drive a laser power source 
 using
   the spindle pwmgen. The minimum frequency must be 20khz. I read in 
 the
   manual that pwmgen is not good on higher frequency. The question is 
 will
   it reach 20khz or must I rather try using a stepgen?
 
 Stegen won't work either, that's a variable rate output, not a
 variable duty-cycle,
 
 The problem at high frequencies with pwmgen isn't with the component,
 it is with the base-thread frequency.
 What is your base-thread frequency? The output can turn on and off at
 that frequency for 50% duty cycle.
 As you drop the base frequency the number of possible duty-cycles 
 increases.
 
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Re: [Emc-users] Max spindle PWM frequency

[Karlsson Wang]

I have not checked the AVR but most micro controllers have timers with hardware 
support or duty cycle measurement. XMC4xxx or STM334 devopment boards have high 
resolution timers equal to a frequency about a few gigahertz.


On Tue, 25 Aug 2015 21:09:08 +1000
Erik Christiansen dva...@internode.on.net wrote:

 On 25.08.15 10:30, Marius Liebenberg wrote:
  I have a couple of Teensy 3.0 boards in the drawer here and they are 
  pretty fast enough I think.
  I am a bit allergic to the USB interface when one uses high current 
  switching devices on the machine. The USB interface is not that 
  reliable.
 
 It would not be hard to use one Arduino timer in capture mode to measure
 M/S ratio of a low frequency PWM input (from LinuxCNC), then replicate
 the ratio on a higher frequency output on another timer. If the ratio of
 input and output frequencies were a binary multiple, then dividing the
 input mark to fit the higher frequency output would only be a right
 shift of the requisite number of bits. (The AVR does not have hardware
 multiply, but software multiply would be OK, if preferred, if the PWM
 ratio doesn't change at a crazy high rate.)
 
 An interrupt on capture complete would be infinitely more efficient
 than any polling hack, for input PWM measurement. The output timer would
 just run with auto-reload, responding to a new M/S ratio in the next cycle
 after it is written to the hardware register.
 
 A 20 MHz part could run 10 bits of count at 20 kHz, giving 0.1%
 resolution. Go for something like 9 bits, 40 kHz, and 0.2%, maybe?
 
 But mebbe you have all that figured, already. :-)
 
 Erik
 
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Re: [Emc-users] Spurious machine state changes, updates

[Karlsson Wang]

If I remember correctly I heard somewhere stop is not allowed to be a toggle 
button.

Regards Nicklas Karlsson



On Tue, 11 Aug 2015 08:06:51 -0400
lloyd wilson llwilso...@rochester.rr.com wrote:

 I think I've solved the state change conundrum I asked about last week -
 
 While watching the debug messages (using 0x11c0 debug setting), a 
 deactivation event occurred, causing a 'emcTaskPlanClose' event, but 
 nothing that indicated the precipitant event. I backed the machine to a 
 previous program point and restarted - bad move; I had picked  the wrong 
 restart point and had to e-stop the machine. However, the e-stop 
 generated the same plan close event report - H
 
 As I originally reported, there is no HAL pin associated with the 
 machine's active/inactive state - but there is for e-stop (e-stop chain 
 activates a relay, one pole of which goes to emc-enable-in). The relay 
 is a recycled dry contact unit, so there is a potential for noisy 
 connections. After adding a debounce function to the e-stop signal, no 
 further instances of the state change phenomenon have been observed, so 
 it looks like that demon has been exorcised.
 
 However, this does raise a question about LCNC's e-stop behavior: at 
 initial startup, we have to manually exit e-stop state via the user 
 panel, but thereafter e-stop state tracks the HAL pin, so a noise spike 
 on e-stop can bump the machine to inactive state and leave no trace 
 (unless there is a debug setting I missed). At the least, such 
 asymmetrical behavior can lead to confusion (see current writer). Given 
 that e-stop is a cataclysmic event, I would think it more appropriate 
 for an e-stop event to latch the machine's state and require a manual 
 reset, as at system startup.
 
 Is there a specific rationale for the way e-stop is currently handled?
 
 Thanks to all who offered suggestions
 
 -ldw
 
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Re: [Emc-users] Wire EDM

[Karlsson Wang]

I have an old Sodick wire EDM I should give a try at home, it never booted 
properly probably because a problem with the discettes.




On Fri, 7 Aug 2015 10:40:08 +0100
andy pugh bodge...@gmail.com wrote:

 I just found this on YouTube
 https://www.youtube.com/watch?v=qoV8UXtLYmE
 
 I though that the inability of LinuxCNC to rewind a path would be a
 problem, but it appears to be working.
 
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Re: [Emc-users] Wire EDM

[Karlsson Wang]

I have an old Sodick wire EDM I should give a try at home, it never booted 
properly probably because a problem with the discettes.




On Fri, 7 Aug 2015 10:40:08 +0100
andy pugh bodge...@gmail.com wrote:

 I just found this on YouTube
 https://www.youtube.com/watch?v=qoV8UXtLYmE
 
 I though that the inability of LinuxCNC to rewind a path would be a
 problem, but it appears to be working.
 
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Re: [Emc-users] Encoder filtering

[Karlsson Wang]

I guess these defects may be available although much smaller even on a 
perfect encoder. TTL circuits quite usually have quite different rise and 
fall time but I even though i did not measure I guess it may be the same for 
CMOS circuits. I also expect less than perfect phase shift but I may be wrong, 
it all depends on if it is equally hard to get distance between pulses on same 
quadrature equally spaced as these phase.

I do speed estimation by measuring time between positive flank on one 
quadrature input which is similar but do not use all four flanks. I would guess 
measuring 4 sample moving average which is equal to time between four flanks 
will be the best algorithm unless change of speed during this period is larger 
than noise. I say his algorithm is very good.


Nicklas Karlsson



On Sun, 02 Aug 2015 19:21:09 -0400
John Kasunich jmkasun...@fastmail.fm wrote:

 Andy:
 
 He has a homemade encoder with less than perfect 50/50
 duty cycle and less than perfect 90deg phase shift.  So he
 gets velocity jitter.  He's trying to make a 4 sample moving
 average, since the jitter should cancel out over a full quadrature
 cycle.
 
 In theory that will be faster responding than a lowpass filter.
 Since the velocity feedback is used in a spindle speed loop,
 adding delay (the lowpass) makes tuning harder.
 
 Gene:
 
 If you XOR the two quadrature signals together you'll get one
 edge (rising or falling) on every transition.
 
 The HAL oneshot component can be configured to produce
 a pulse on both rising and falling edges.
 
 
 
 On Sun, Aug 2, 2015, at 05:42 PM, andy pugh wrote:
  On 2 August 2015 at 16:32, Gene Heskett ghesk...@wdtv.com wrote:
   I need a net signal to strobe the 4 sample_hold .hold's, how can that be
   obtained?
  
  I think we would need more information about what it is you are trying
  to do, and how you are trying to do it.
  What are you trying to do that normal denounce and lowpass won't do?
  
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Re: [Emc-users] Gear hobbing machine

[Karlsson Wang]

I guess you have start calculation from the encoder counters each time and then 
there will be no problem with add up over time.

Nicklas Karlsson



On Thu, 30 Jul 2015 09:44:02 -0400
John Kasunich jmkasun...@fastmail.fm wrote:

 
 
 On Wed, Jul 29, 2015, at 09:35 PM, richsh...@comcast.net wrote:
  I am adapting a version of the little hobber and want to use linux-CNC to 
  do the ratio division between the hob and the work spindles. Additionally, 
  a third axis that is actually the feed needs to be incorporated. Any 
  thoughts. 
 
 The encoder-ratio HAL component was invented with this specific use in mind.
 http://linuxcnc.org/docs/html/man/man9/encoder_ratio.9.html
 
 It is a software based encoder counter (like the regular software encoder 
 counter), but it does the math differently to avoid some problems that can 
 happen if you use a more normal approach.
 
 The normal approach would be to use either software or hardware encoder 
 counters to measure the position of each axis, then scale the positions based 
 on the tooth ratios, and eventually compare them to determine how to drive 
 the slave axis.  The problem is that if you run long enough you start running 
 out of accuracy.  Imagine that your hobber has been running for hours.  You 
 might find yourself subtracting 100,000,000.03 revolutions of the master from 
 100,000,000.05 revolutions of the slave.  If the math doesn't have enough 
 significant digits, the 0.02 revolution difference gets lost in the noise.
 
 The encoder ratio component uses a different approach to the math, and will 
 never run out of accuracy no matter how long it goes.
 
 -- 
   John Kasunich
   jmkasun...@fastmail.fm
 
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Re: [Emc-users] Switches for home, limits

[Karlsson Wang]

A simple RC filter possibly combined with voltage division will remove noise 
although it will also reduce accuracy.

I think low input impedance will fix the problem with noise because even though 
voltage may be high only a limited amount of current may be transferred by 
capacitive coupling or an electric field.


Nicklas Karlsson
Micropower




On Thu, 30 Jul 2015 08:02:45 +0100
Marcus Bowman marcus.bow...@visible.eclipse.co.uk wrote:

 
 On 30 Jul 2015, at 03:51, Gene Heskett wrote:
 
  I bought a bag of small, roller tipped microswitches, and have a couple 
  mounts laid out but not carved yet.
  
  Going thru searches on ebay just now, for both inductive, capacitative, 
  and IR proximity switches, It sees like the majority of them are needing 
  6 volts or more, and around 300 ma each to function.  Having seen some 
  micropower capacitative switches in the textbooks of yore, it seems like 
  the ball has been dropped in terms of being useful in a 5 volt logic 
  circuit.
  
  Both the microswitch, and the inductive versions would seem to be 
  sensitive to collecting swarf, particularly if its a rare earth magnet 
  running a reed switch.
  
  My lathe seems to be relatively happy with a microswitch located under 
  the back edge of the bed for Z homing where swarf tends to fall on past 
  it, but x has to be kept swept clean because its actually on top of the 
  carriage.
  
  I see a whole passel of stuff drilled onto GO704's in the hits I can get 
  from google, but all of them preclude retaining the rubber swarf 
  shields, which I'd say was not worth the tradeoff.  There has to be a 
  better way.
  
  So what sort of switches, and what swarf shielding to keep them 
  relatively clean  accurate are others using?
  
  PM's with pix appreciated if you have the time.
  
 
 Actually, this is a really interesting question. Having spent ages thinking 
 about shielded locations for the mill, and about to do the same for the 
 lathe, it would be useful if folks could put the pictures somewhere we could 
 all see them.
 If anyone has any recommendations about makes and models of switches/sensors 
 which provide better accuracy and repeatability than others, or useful ways 
 of providing adjustment on mounting arrangements, that would also be very 
 useful.
 
 Marcus
 
  Thanks.
  
  Cheers, Gene Heskett
  -- 
  There are four boxes to be used in defense of liberty:
  soap, ballot, jury, and ammo. Please use in that order.
  -Ed Howdershelt (Author)
  Genes Web page http://geneslinuxbox.net:6309/gene
  
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Re: [Emc-users] Gear hobbing machine

[Karlsson Wang]

Sounds great. I bough a few hundred kilos of material probably intented for 
gears from bankcrupt company which i intend to use for testing machine.


Nicklas Karlsson



On Thu, 30 Jul 2015 10:09:51 +0100
andy pugh bodge...@gmail.com wrote:

 On 30 July 2015 at 07:16, Dave Caroline dave.thearchiv...@gmail.com wrote:
  Andy has implemented it on a mill
  http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Hobbing
 
 I have now created a dedicated hobbing GladeVCP panel which performs
 basic gear calculations (including span across teeth for size
 checking) as well as running the hobbing process.
 
 I will try to remember to add it to the Wiki page.
 
 
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Re: [Emc-users] minimum spindle speed

[Karlsson Wang]

If spindle motor is an asynchronous motor and simple voltage frequency control. 
Are your sure voltage frequency characteristics are correctly set?

If motor get hot on low RPM even then not loaded you will almost certainly use 
to high voltage.


Nicklas Karlsson



On Mon, 22 Jun 2015 13:48:23 -0400
Tom Easterday tom-...@bgp.nu wrote:

 I am controlling a spindle motor with a VFD commanded by modbus.  My current 
 speed range is 0-3500 rpm.  If I run the spindle below 275 rpm the current 
 spikes and triggers the VFD’s protection shutoff.  How do I set the minimum 
 spindle speed so that the user can’t command a speed below 275rpm?
 -Tom
 
 
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[Emc-users] Ethernet --Ethercat (was Serial FPGA buses/interconnections)

[Karlsson Wang]

For ordinary Ethernet there cheap development boards available with an Ethernet 
connector. I use the 7i80 but will change to standard protocol as soon as there 
is time.

Ethercat require two Ethernet connectors and as signals are changed while 
passing thru also special hardware. As is now I have not seen any cheap 
development boards with Ethercat.

To multicast control signals to several Ethernet devices at once should be no 
problem but to send for example measurement values from several Ethernet 
devices at once is not possible with Ethernet but with Ethercat. I consider 
Ethercat superior since it would be no performance penalty to divide work on 
several devices but difference is probably not to large for most cases.


Nicklas Karlsson

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Re: [Emc-users] Serial FPGA buses/interconnections [Was: Sandy box]

[Karlsson Wang]

I am already using the 7i80 code on Micro controller although currently only 
running on desktop with servo motor from real machine.

Nicklas Karlsson


On Mon, 8 Jun 2015 17:07:36 +
Ralph Stirling ralph.stirl...@wallawalla.edu wrote:

 Philipp,
 
 You should look at the ethernet-based system Peter Wallace created for
 the Mesa cards.  The FPGA firmware and drivers for the Mesa system is
 open source.  The 7I92 or 7I80DB should have some code examples you
 can look at.
 
 -- Ralph
 
 From: Philipp Burch [p...@hb9etc.ch]
 Sent: Monday, June 08, 2015 9:06 AM
 To: emc-users@lists.sourceforge.net
 Subject: Re: [Emc-users] Serial FPGA buses/interconnections [Was: Sandy box]
 
 Hi Dave!
 
 On 08.06.2015 15:43, Dave Cole wrote:
 
  ___
   From the Ethercat Technology Group membership application page:
 
  The membership cost is pretty low... !!!  :-)
 
  And there are some sample Ethercat master and slave source code available
 
  http://www.ethercat.org/en/products/4F84049B9950437FB34749A52AB20786.htm
  http://www.ethercat.org/en/products/54FA3235E29643BC805BDD807DF199DE.htm
 
  There is also at least one Ethercat open source master repository out
  there..
 
  http://sourceforge.net/projects/soem.berlios/
 
  Dave
 
 
 Good to know that it's free of charge. But since I'm mainly interested
 in the slave part, things are not that easy: Their slave sample code is
 for a microncontroller interfacing the EtherCAT-ASIC, so they're just
 making their money somewhere else ;)
 
 Thanks,
 Philipp
 
 
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Re: [Emc-users] If there's one thing I hate, all the noise, noise, noise, noise

[Karlsson Wang]

I guess a common mode filter will be good but I have almost only theoretical 
knowledge and very limited experience.

Nicklas Karlsson



On Thu, 14 May 2015 10:38:43 -0400
Rick Lair r...@superiorroll.com wrote:

 I have been following this thread somewhat, and have a question,
 
 What is the difference between a line reactor and emi input filter?
 
 We have a AD GS3 40hp drive in our turning center, and have the same 
 noise problems with the drive, and I am not sure which one to buy, or do 
 I need both? The drive schematic shows putting an emi filter on both 
 sides of the drive, would that help as well? At $272 bucks a piece, I 
 don't want to throw money away, but I do want to get this put to bed, we 
 have been dealing with it for 2 years now, and I am getting tired of it.
 
 Thanks
 
 Rick
 
 On 5/14/2015 9:53 AM, Dave Cole wrote:
  The Rasmi input filter
  Take it off and see what happens
 
  If that drive is screwing with your keyboard that is on the OUTSIDE of your 
  control cabinet, imagine what kind of RF exposure is on the inside of your 
  control cabinet!
 
  Those AD VFDs should also be sold as EMI test generators.  ;-)
 
  Dave
 
 
 
  On 5/14/2015 8:53 AM, Tom Easterday wrote:
  I spent some time with the spectrum analyzer but did’t have much luck in 
  isolating the sink for the noise.  I just verified that my VFD does indeed 
  produce a large amount of noise between low kHz and about 10MHz!  I did 
  some re-routing of wires and replaced some that weren’t shielded.  I 
  ordered some ferrites for the VFD-motor wiring and my computer I/O 
  extension cabling which will be here in a couple days.
 
  However, I did find the source of the main problem!  It was indeed my 
  keyboard.  Not the USB wiring from keyboard to pc, but the keyboard ITSELF 
  is very sensitive to the noise created by the VFD.  If I move the keyboard 
  to the very extreme end of it’s (rather long) usb cable the problem 
  disappears completely. 6” closer to the cabinet and noise reappears.  
  Apparently the noise is being interpreted as key presses by the keyboard 
  circuitry.  I replaced the new water resistant Logitech keyboard with a 
  very old Apple keyboard I had lying around and no more random characters!  
   I also had a second problem where the VFD would shut down somewhat 
  randomly which I thought was related to this noise as well.  That turned 
  out to be an over current condition at very low rpm.  Tweaking some 
  settings fixed that.
 
  The Rasmi input filter, and various re-wiring and shielding I did was 
  probably not needed, but in the long run perhaps it will save me from 
  other problems.
 
  Thanks, for all the input,
  -Tom
 
 
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Re: [Emc-users] If there's one thing I hate, all the noise, noise, noise, noise

[Karlsson Wang]

I forgot to mention. There is a capacitance between motor cables and protective 
earth. Then the motor is driven by the VFD it is supplied with square wave 
voltages at high frequency and at each switching the capacitance is discharged 
or charged. As impedance at high frequency is far from zero in the power cables 
the ground will bounce around. If i think correctly both the protective and the 
rectified power ground will bounce around in opposite directions but I have 
never measured this.

The common mode impedance may be rised by adding a common mode inductur in the 
loop.

Nicklas Karlsson



On Thu, 14 May 2015 10:38:43 -0400
Rick Lair r...@superiorroll.com wrote:

 I have been following this thread somewhat, and have a question,
 
 What is the difference between a line reactor and emi input filter?
 
 We have a AD GS3 40hp drive in our turning center, and have the same 
 noise problems with the drive, and I am not sure which one to buy, or do 
 I need both? The drive schematic shows putting an emi filter on both 
 sides of the drive, would that help as well? At $272 bucks a piece, I 
 don't want to throw money away, but I do want to get this put to bed, we 
 have been dealing with it for 2 years now, and I am getting tired of it.
 
 Thanks
 
 Rick
 
 On 5/14/2015 9:53 AM, Dave Cole wrote:
  The Rasmi input filter
  Take it off and see what happens
 
  If that drive is screwing with your keyboard that is on the OUTSIDE of your 
  control cabinet, imagine what kind of RF exposure is on the inside of your 
  control cabinet!
 
  Those AD VFDs should also be sold as EMI test generators.  ;-)
 
  Dave
 
 
 
  On 5/14/2015 8:53 AM, Tom Easterday wrote:
  I spent some time with the spectrum analyzer but did’t have much luck in 
  isolating the sink for the noise.  I just verified that my VFD does indeed 
  produce a large amount of noise between low kHz and about 10MHz!  I did 
  some re-routing of wires and replaced some that weren’t shielded.  I 
  ordered some ferrites for the VFD-motor wiring and my computer I/O 
  extension cabling which will be here in a couple days.
 
  However, I did find the source of the main problem!  It was indeed my 
  keyboard.  Not the USB wiring from keyboard to pc, but the keyboard ITSELF 
  is very sensitive to the noise created by the VFD.  If I move the keyboard 
  to the very extreme end of it’s (rather long) usb cable the problem 
  disappears completely. 6” closer to the cabinet and noise reappears.  
  Apparently the noise is being interpreted as key presses by the keyboard 
  circuitry.  I replaced the new water resistant Logitech keyboard with a 
  very old Apple keyboard I had lying around and no more random characters!  
   I also had a second problem where the VFD would shut down somewhat 
  randomly which I thought was related to this noise as well.  That turned 
  out to be an over current condition at very low rpm.  Tweaking some 
  settings fixed that.
 
  The Rasmi input filter, and various re-wiring and shielding I did was 
  probably not needed, but in the long run perhaps it will save me from 
  other problems.
 
  Thanks, for all the input,
  -Tom
 
 
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 Thanks
 
 
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 Superior Roll  Turning LLC
 399 East Center Street
 Petersburg MI, 49270
 PH: 734-279-1831
 FAX: 734-279-1166
 www.superiorroll.com
 
 
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Re: [Emc-users] If there's one thing I hate, all the noise, noise, noise, noise

[Karlsson Wang]

Grounding. Power ground must be separated from small signal ground.

The VFD also generate a common mode voltage and unless a common mode inductor 
is added to increase common mode impedance there will be a high frequency 
current flowing thru the protected earth wire which in combination with the 
protected earth cable impedance at high frequency will make it bounce around. I 
know about two paths for the common mode voltage: capcitance inside the VFD to 
protected earth and between motor cables and protected earth.

Nicklas Karlsson



On Mon, 11 May 2015 21:00:39 -0400
Tom Easterday tom-...@bgp.nu wrote:

 Early on we made a decision to put our VFD into the same cabinet as the rest 
 of the electronics on a lathe retrofit - I originally had two separate 
 cabinets, one for power with vfd and one for electronics.  This was to save 
 space and bring the size of the cabinet on the machine down to a more 
 reasonable size so it might fit through doors, etc.  In retrospect, perhaps 
 that was a bad idea.  But here we are trying to address VFD induced noise 
 problems.   The cabinet is shown in a picture here:
 https://www.flickr.com/photos/37438950@N00/17219261571/in/album-72157651167328249/
  
 https://www.flickr.com/photos/37438950@N00/17219261571/in/album-72157651167328249/
   There is actually more wiring completed now then what is shown in the 
 picture but you get the idea.
 
 After having read about folks often using Rasmi input power filters to solve 
 noise issues I purchased one from ebay and installed it today.  It didn’t 
 help, and may have actually made the problem worse.  I installed it very 
 close to the VFD input power terminals as recommended.
 
 When I run the spindle motor on it’s lowest RPM I hear a high pitched whine 
 (at the motor) and strange things begin to happen in Axis.  Windows pop up, 
 perhaps a homing window, perhaps a touch off, perhaps Axis switches to MDI 
 mode, sometimes it turns the machine off, sometimes it turns the machine off 
 but the spindle keeps moving!   Sometimes the VFD shuts off and displays oL 
 1” on the screen.
 
 So now I want to understand how this noise is getting into the PC. I first 
 thought it was because the keyboard, mouse, and video cables ran past the VFD 
 in the cabinet and noise was being induced on the keyboard cable.  So in 
 trying to isolate where the issue was I disconnected those cables and ran 
 them far away from the VFD.  No help..  I then wondered if it was coming in 
 the AC power to the PC, so I rerouted the PC power to a completely different 
 outlet outside of the cabinet.  No help.  I then rerouted the network and 
 video cables to get those away from the VFD, no help again.   Even with the 
 door open (as you see in the picture) I have noise.  The only thing 
 connecting the PC to the rest of the system is the parallel cable which is 
 about 12” long that connects to the Mesa 7i85s card (and again, that is at 
 the other end of my cabinet from the VFD).  Today I borrowed a friend’s 
 0-1Ghz spectrum analyzer to see if I can find the source/frequency of the 
 noise and/or where it might be getting to the PC.  I will start playing with 
 that tomorrow.  
 
 I am wondering if anyone has any ideas of where i can look, or what I can do?
 -Tom
 
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Re: [Emc-users] Servo Motor Question

[Karlsson Wang]

Mechanical problem?



On Mon, 11 May 2015 11:10:52 -0400
Rick Lair r...@superiorroll.com wrote:

 Its Linuxcnc controlled, and has been running fine for over a year, the 
 operators started noticing a poor finish on the parts just as of recent. 
 The material is hardened D2 Tool steel, and we are using ceramic and 
 diamond inserts, so machine issues, even very small and non noticeable 
 on a piece of A-36 HR, stick out like a sore thumb on this material.
 
 
 Rick
 
 
 On 5/11/2015 11:05 AM, andy pugh wrote:
  On 11 May 2015 at 15:53, Rick Lair r...@superiorroll.com wrote:
  Any thoughts/ pointers as to what may be causing this?
  It sounds like the PID tuning might be off. Is this
  LinuxCNC-controlled or is it a standalone PID?
 
 
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 Thanks
 
 
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 Superior Roll  Turning LLC
 399 East Center Street
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 PH: 734-279-1831
 FAX: 734-279-1166
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Re: [Emc-users] Mesa cards visual documentation

[Karlsson Wang]

Symbol handling have problem, you have to set up local symbol directory and 
restart Geda to make it show up. Once added there is or you add yourself a 
source attribute with thee filename as value. It is not perfect but work 
relatively well once added and to improve might be a lot better and less work 
than a totally new editor.


On Tue, 21 Apr 2015 19:09:26 -0500
TJoseph Powderly tjt...@gmail.com wrote:

 wow
 i spent a lot of time in Geda  Gschem
 i did not know subsheets wer possible
 thanks!
 ( have to re-install it and try hal2gschem again )
 tomp tjtr33
 
 On 04/21/2015 11:14 AM, Karlsson  Wang wrote:
  Hierchical design in Geda is not to bad. In particular it is possible to 
  make several instances of same component which is a sub sheet. Naming of 
  components on PCB is however horrible long.
 
  Nicklas Karlsson
 
 
 
  On Mon, 20 Apr 2015 23:05:03 +0100
  andy pugh bodge...@gmail.com wrote:
 
  On 20 April 2015 at 22:27, TJoseph Powderly tjt...@gmail.com wrote:
 
  the idea needs to have 'meta' components so the complexity can be
  reduced ( like pages in hierarchical schematics)
 
  I do wish that I was free to share the documentation we get for the
  PCM software at work.
 
  Imagine 40,000 pages of Simulink diagrams nested 10 layers deep in 
  places...
 
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Re: [Emc-users] Mesa cards visual documentation

[Karlsson Wang]

Hierchical design in Geda is not to bad. In particular it is possible to make 
several instances of same component which is a sub sheet. Naming of components 
on PCB is however horrible long.

Nicklas Karlsson



On Mon, 20 Apr 2015 23:05:03 +0100
andy pugh bodge...@gmail.com wrote:

 On 20 April 2015 at 22:27, TJoseph Powderly tjt...@gmail.com wrote:
 
  the idea needs to have 'meta' components so the complexity can be
  reduced ( like pages in hierarchical schematics)
 
 I do wish that I was free to share the documentation we get for the
 PCM software at work.
 
 Imagine 40,000 pages of Simulink diagrams nested 10 layers deep in places...
 
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Re: [Emc-users] Mesa cards visual documentation

[Karlsson Wang]

Threads are not signals traveling thru the system, they just decide how often 
the signal will travel so I guess they could be attributes although they 
perform a similar functionality as a clock signal. If threads are implemented 
as symbols I guess a single clock output might be an option.

It is possible to design threads but it could be improved. It is also possible 
to draw buses with several signals but this could also be improved. If Geda 
editor is not a good option there are three different approaches: Write a new 
editor, improve Geda or find another editor.


Nicklas Karlsson




On Mon, 20 Apr 2015 16:27:24 -0500
TJoseph Powderly tjt...@gmail.com wrote:

 Hello Nicklas
 look at
 http://wiki.linuxcnc.org/cgi-bin/wiki.pl?HalSchematicsUsingGschem
 there are libraries too
 
 please realize these are only for info
 the project was unfinished as i was disappointed in the view scale
 and how to handle threads.
 in general the drawings are just too big
 the idea needs to have 'meta' components so the complexity can be 
 reduced ( like pages in hierarchical schematics)
 
 hth
 TomP tjtr33
 
 
 On 04/20/2015 03:49 PM, Karlsson  Wang wrote
  rockhopper geda eagle may be incomplete from some view but the idea is not!
 
  I think the netlist approach is the correct path since it is well proven 
  and used by I think almost all schematic capture applications. There are 
  however a lot of different format 
  http://manpages.ubuntu.com/manpages/karmic/man1/gnetlist.1.html so the 
  starting point is hard to decide, add a *.hal format?
 
  I have not seen the Geda effort but I guess Linuxcnc had to have a symbol 
  library?
 
  Then there is a symbol library for the linuxcnc parts and a suitable 
  netlist format and the editor is not good or need to be integrated this is 
  the second step.
 
 
  Nicklas Karlsson
 
 
 
  On Sun, 19 Apr 2015 20:58:45 -0500
  TJoseph Powderly tjt...@gmail.com wrote:
 
  On 04/19/2015 01:40 PM, andy pugh wrote:
  On 19 April 2015 at 18:31, Karlsson  Wang
  nicklas.karls...@karlssonwang.se wrote:
  I guess it would be possible to modify or make Linuxcnc accept a netlist 
  as a hal file and in such case for example Geda could be used for 
  configuration. What do you think?
 
  It has been tried:
  http://wiki.linuxcnc.org/cgi-bin/wiki.pl?HalSchematicsUsingGschem
  http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Eagle2HAL
 
  But that does rather the same thing that Rockhopper does, but not as 
  prettily.
 
  i think rockhopper does not output hal from a drawing.
  i think it 'just' displays a visualization of a hal file.
  it's not a design tool, its a proofing tool.
 
  I think the Geda and Eagle attempts were the other direction,
  they attempted to visually create netlists using a gui pallete of comps.
 
  ( iirc i tried to read _and_ write hal files )
 
  any 'pretty' in Geda/Eagle is up to the designer
  (s)he can drag and drop
  or rearrange as (s)he likes
 
  no modifications allowed in the rockhopper output
  you cant re-arrange the svg to make sense of one knot.
 
  your back to   edit compile debug (repeat)
 
  rockhopper geda eagle are all incomplete from some view
 
  tomp tjtr33
  ( i wrote the miserable Geda effort :(
 
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Re: [Emc-users] Mesa cards visual documentation

[Karlsson Wang]

rockhopper geda eagle may be incomplete from some view but the idea is not!

I think the netlist approach is the correct path since it is well proven and 
used by I think almost all schematic capture applications. There are however a 
lot of different format 
http://manpages.ubuntu.com/manpages/karmic/man1/gnetlist.1.html so the starting 
point is hard to decide, add a *.hal format?

I have not seen the Geda effort but I guess Linuxcnc had to have a symbol 
library?

Then there is a symbol library for the linuxcnc parts and a suitable netlist 
format and the editor is not good or need to be integrated this is the second 
step.


Nicklas Karlsson



On Sun, 19 Apr 2015 20:58:45 -0500
TJoseph Powderly tjt...@gmail.com wrote:

 On 04/19/2015 01:40 PM, andy pugh wrote:
  On 19 April 2015 at 18:31, Karlsson  Wang
  nicklas.karls...@karlssonwang.se wrote:
  I guess it would be possible to modify or make Linuxcnc accept a netlist 
  as a hal file and in such case for example Geda could be used for 
  configuration. What do you think?
 
  It has been tried:
  http://wiki.linuxcnc.org/cgi-bin/wiki.pl?HalSchematicsUsingGschem
  http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Eagle2HAL
 
  But that does rather the same thing that Rockhopper does, but not as 
  prettily.
 
 i think rockhopper does not output hal from a drawing.
 i think it 'just' displays a visualization of a hal file.
 it's not a design tool, its a proofing tool.
 
 I think the Geda and Eagle attempts were the other direction,
 they attempted to visually create netlists using a gui pallete of comps.
 
 ( iirc i tried to read _and_ write hal files )
 
 any 'pretty' in Geda/Eagle is up to the designer
 (s)he can drag and drop
 or rearrange as (s)he likes
 
 no modifications allowed in the rockhopper output
 you cant re-arrange the svg to make sense of one knot.
 
 your back to   edit compile debug (repeat)
 
 rockhopper geda eagle are all incomplete from some view
 
 tomp tjtr33
 ( i wrote the miserable Geda effort :(
 
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Re: [Emc-users] Need a SWAG

[Karlsson Wang]

Increase in speed should almost certainly be 48/28 faster. I think this is true 
for acceleration to. Then you just have to hope for the electric motor to 
tolerate the higher voltage and for the mechanics to tolerate higher 
speed/acceleration.

Nicklas Karlsson



On Sat, 18 Apr 2015 21:02:22 -0400
Gene Heskett ghesk...@wdtv.com wrote:

 Greetings;
 
 I am in the midst of replacing the 28 volt motor supply on my mill with a 
 48 volt contraption.
 
 This should, all other things remaining equal, allow me to make my accel 
 setting a little faster, and the MAX_VEL's a bunch faster.
 
 Since I am going from 28 volts to 48 volts, is there a general rule of 
 thumb way to determine the ratio of increase I can put in my .ini file?
 
 Thanks everybody.
 
 Cheers, Gene Heskett
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Re: [Emc-users] Mesa cards visual documentation

[Karlsson Wang]

The *.hal files fulfill a similar functionality as a netlist in schematic 
capture software. Difference is signals exist in software instead of on a 
circuit board. I guess it would be possible to modify or make Linuxcnc accept a 
netlist as a hal file and in such case for example Geda could be used for 
configuration. What do you think?

Nicklas Karlsson



On Thu, 16 Apr 2015 09:05:35 +0300
Marius Alksnys marius.alks...@gmail.com wrote:

 On 2015.04.15 17:13, Erik Christiansen wrote:
  On 13.04.15 23:57, Ralph Stirling wrote:
  Looks useful, Marius.  I use Kicad rather than Eagle though.
  The individual diagrams I found at the link were PDFs, and did not
  require Eagle for viewing. What is used for generating PDF doco seems to
  be of relevance predominantly to the creator?
 
 I created Eagle library to be able to make electric schematics for 
 electrical connections in control cabinets of machines. I know Eagle is 
 meant for designing PCBs, but I can't find better (easy to learn, with 
 lots of libraries, scriptable, popular, multi-platform, with free 
 version available) software for electrical schematics.
 
 
  Incidentally, Eagle seems to be something of a LinuxCNC standard, if we
  have any, in that it is more commonly used for HAL and ClassicLadder
  related diagrams than anything else, AFAICT.
 Have to check this again, probably learn how to...
 I use text editor to create / edit HAL files.
 
 
  Erik
 
 
 
 
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Re: [Emc-users] Need a SWAG

[Karlsson Wang]

Oh i didn't think about stepper. The equations are useful for DC, BLDC, PMSM, 
Asyncronous and probably also for switched reluctance.



On Sun, 19 Apr 2015 14:19:04 -0400
Gene Heskett ghesk...@wdtv.com wrote:

 On Sunday 19 April 2015 10:22:40 Karlsson  Wang wrote:
  Motor torque depends on current. Then increasing acceleration torque
  will also increase but how much depends on the inertia, there
  rotational inertia and the mass moved. It is also possible there are
  some viscous load which depend on speed of motion or rotational load.
  I assume current will increase but how much I have no idea.
 
  Electric motor generate a back EMF which depend on rotational speed so
  there is less voltage left to increase current/torque at high speed
  and more available voltage left to decrease speed.
 
  Here
  http://en.wikipedia.org/wiki/Brushed_DC_electric_motor#Torque_and_spee
 d_of_a_DC_motor the voltage balance and torque equations a little bit
  more than half way down in the document is incredibly good knowledge
  if working with servo motors. It is also useful to think about this
  equations then working with other types of electric motors. The
  equations are actually so important i think it would be a good idea to
  include them in the Linuxcnc manual maybe in the integrator chapter
  and I could provide some help if I have enough time.
 
 We are slightly at odds Nicklas. You are talking servo's correctly, and I 
 am talking steppers. These are different critters.
 
 The servo's you refer to will allow a small error and catch up when they 
 can, which may or may not wreck your part depending of the tolerances.  
 Steppers OTOH, will stall under the same conditions, wrecking the part 
 and likely breaking the tool too when the direction reverses at the end 
 of that move  So one has to be quite considerably more cautious, even 
 paranoid, about how much you ask of them in the speed ranges where the 
 torque to stay precisely on the path may be iffy, particularly in a 
 complex part that may be quite a few loops thru the code to do the depth 
 the job needs.
 
 One of those consideration is available spindle horsepower, as in lack 
 thereof, its a 200 watt motor!  I intend to switch it out at some point, 
 putting the 400 watter I took out of the lathe in its place, making it a 
 2 speed range belt drive when I do, all of which I will have to design  
 make.  It, for some jobs, needs both 5x the rpms to get above any 
 framing resonances and a higher feed rate just to enhance the tool life 
 by cutting deeper into cooling wood when I am carving wood.  The wood, 
 if the tool is sharp, doesn't burn, but the bit can turn straw colored 
 occassionaly.
 
 But thats off topic and I haven't really started on a design for that 
 yet.
 
 The higher voltage psu and a 5i25 card I just ordered are this springs 
 project.  The motor is a different critter.
 
  Regargs Nicklas Karlsson
 
 
 
  On Sun, 19 Apr 2015 05:55:31 -0400
 
  Gene Heskett ghesk...@wdtv.com wrote:
   On Sunday 19 April 2015 02:58:14 Karlsson  Wang wrote:
Increase in speed should almost certainly be 48/28 faster. I think
this is true for acceleration to. Then you just have to hope for
the electric motor to tolerate the higher voltage and for the
mechanics to tolerate higher speed/acceleration.
  
   Humm, I would have to assume that since the motor currents would not
   be similarly increased, that the accels, wouldn't be enhanced by
   anywhere near that same ratio.
  
   The motors ultimate torque shouldn't change, just the speed at which
   the torque falls off due to inductance?
  
   At present I do not believe the applied accels are modulated in the
   TP to be slower at the higher motor speeds where torque is falling
   off, so we need to use an accel it can handle in spite of the
   falloff.  This costs us time at the lower speeds where there is
   generally plenty of torque.
  
   IMO, the accel should be applied with something that looks like a
   t=rc time constant mapping, but that would not be optimum for the
   needed decel since that would start a new t=rc curve, a fast slowing
   at an rpm point where the torque is not available.
  
   Experimentally I have found I can move the existing setup at 22 ipm
   in the range where table weights are well balanced if I use really
   slow accels like 2 seconds or more to top speed.  But for anything
   like decent accel settings, I'll stall at 10 ipm or less so I
   generally use sub 10 ipm moves now.  One of the reasons for kicking
   the motor voltage up closer to the limits of the drivers, 50 volts
   in the case of the 2M542 driver.
  
Nicklas Karlsson
  
   Thanks Nicklas.  At least I have a starting point now for how much
   faster I can go.  I got the new psu mounted with  cooling arranged
   yesterday, but not hooked up yet.
  
   Cheers, Gene Heskett
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Re: [Emc-users] Mesa cards visual documentation

[Karlsson Wang]

Then I am not stupid. I guess hierarchical design in particular and buses may 
help.

Rockhopper? Bicycles? Or the Rockhopper penguin?


Nicklas Karlsson




On Sun, 19 Apr 2015 19:40:46 +0100
andy pugh bodge...@gmail.com wrote:

 On 19 April 2015 at 18:31, Karlsson  Wang
 nicklas.karls...@karlssonwang.se wrote:
  I guess it would be possible to modify or make Linuxcnc accept a netlist as 
  a hal file and in such case for example Geda could be used for 
  configuration. What do you think?
 
 It has been tried:
 http://wiki.linuxcnc.org/cgi-bin/wiki.pl?HalSchematicsUsingGschem
 http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Eagle2HAL
 
 But that does rather the same thing that Rockhopper does, but not as prettily.
 
 -- 
 atp
 If you can't fix it, you don't own it.
 http://www.ifixit.com/Manifesto
 
 --
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Re: [Emc-users] Mesa cards visual documentation

[Karlsson Wang]

Then I am not stupid. I guess hierarchical design in particular and buses may 
help.

Rockhopper? Bicycles? Or the Rockhopper penguin?


Nicklas Karlsson




On Sun, 19 Apr 2015 19:40:46 +0100
andy pugh bodge...@gmail.com wrote:

 On 19 April 2015 at 18:31, Karlsson  Wang
 nicklas.karls...@karlssonwang.se wrote:
  I guess it would be possible to modify or make Linuxcnc accept a netlist as 
  a hal file and in such case for example Geda could be used for 
  configuration. What do you think?
 
 It has been tried:
 http://wiki.linuxcnc.org/cgi-bin/wiki.pl?HalSchematicsUsingGschem
 http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Eagle2HAL
 
 But that does rather the same thing that Rockhopper does, but not as prettily.
 
 -- 
 atp
 If you can't fix it, you don't own it.
 http://www.ifixit.com/Manifesto
 
 --
 BPM Camp - Free Virtual Workshop May 6th at 10am PDT/1PM EDT
 Develop your own process in accordance with the BPMN 2 standard
 Learn Process modeling best practices with Bonita BPM through live exercises
 http://www.bonitasoft.com/be-part-of-it/events/bpm-camp-virtual- event?utm_
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Re: [Emc-users] Mesa cards visual documentation

[Karlsson Wang]

For cabinets it would be useful to count the number of connection points for 
each net, one screw connector for each for those who need screws.

Nicklas Karlsson



On Sun, 19 Apr 2015 19:40:46 +0100
andy pugh bodge...@gmail.com wrote:

 On 19 April 2015 at 18:31, Karlsson  Wang
 nicklas.karls...@karlssonwang.se wrote:
  I guess it would be possible to modify or make Linuxcnc accept a netlist as 
  a hal file and in such case for example Geda could be used for 
  configuration. What do you think?
 
 It has been tried:
 http://wiki.linuxcnc.org/cgi-bin/wiki.pl?HalSchematicsUsingGschem
 http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Eagle2HAL
 
 But that does rather the same thing that Rockhopper does, but not as prettily.
 
 -- 
 atp
 If you can't fix it, you don't own it.
 http://www.ifixit.com/Manifesto
 
 --
 BPM Camp - Free Virtual Workshop May 6th at 10am PDT/1PM EDT
 Develop your own process in accordance with the BPMN 2 standard
 Learn Process modeling best practices with Bonita BPM through live exercises
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Re: [Emc-users] WTF is wrong here

[Karlsson Wang]

Well you have to add drainage on the outside! It might also be good with a 
layer insulation.


http://www.google.se/imgres?imgurl=http://www.anticimex.com/sv/SysContentAssets/6d5ad92fe5de49e581810cbe5f5e2d89/moderna_kallare_har_skyddande_isolering.jpg/imgrefurl=http://www.anticimex.com/sv/se/Privat/Fukt/Grund-och-kallare/Kallare/h=261w=515tbnid=9SGTcNJxIeOUwM:zoom=1docid=YHiPGe1mvgK9BMei=_rsoVdj_JseqswGMhoCgBwtbm=ischved=0CCQQMygFMAU




On Fri, 10 Apr 2015 20:44:41 -0500
Jon Elson el...@pico-systems.com wrote:

 On 04/10/2015 12:14 PM, Gene Heskett wrote:
  Greetings all;
 
  I am in the middle of an attempt to dry up my basement, and I've a sump
  dug about a foot deep 2 feet more to go is the plan, but we had north of
  3 of precip in the last 36 hours and I am losing the battle.
 
 
 I can't help with the G-code, I know the mill operations better.
 
 But, I had a leaky crack in my basement, and used the LCR 
 (Liquid concrete repair) kit sold
 through the internet for under $80 delivered.  I only used 
 half the kit, as it was almost a hairline crack.  It has 
 been over a full year, now, and NOT a DROP of leakage.  It 
 used to make lakes on the basement floor.  So, I highly 
 recommend this stuff.
 We have had several major downpours since I made the fix, 
 and it has held.
 
 Jon
 
 --
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Re: [Emc-users] Not ACME, ballscrews! Re: Anyone have leftovers from a 9x20 CNC conversion?

[Karlsson Wang]

I have a left over ball screw but do not know the price for these, It is around 
2.5 metres long and I bought it used for below $100


On Sat, 28 Mar 2015 23:52:59 -0600
Gregg Eshelman g_ala...@yahoo.com wrote:

 On 3/28/2015 8:46 AM, Gene Heskett wrote:
 
  I need to be finding some good ACME rod for the 9x20 CNC, motors etc.
 
 Scratch the ACME. Today I snagged a homebuilt XY table to cannibalize 
 for parts.
 
 http://boise.craigslist.org/art/4894831991.html
 
 Across the gantry it has a 0.37-ish rolled ballscrew with a nut threaded 
 on one end, with a max OD of .247 I have the saddle channel plowed out 
 to nearly that, can easily go the extra few thou to have it just 
 clearing. Will run a big ballnose down the center if it needs to be 
 lower down. Of course that screw will need shortened a bunch. I plan to 
 give it as much cross slide travel as I can.
 
 The other axis is a vintage Star ballscrew linear actuator made in 
 1997, inside a 2x2 aluminum extrusion with a block on one side. I'll 
 mount that to the side of the bed with the block down (keep the chips 
 out of the open side) and make a dead simple bracket to mount from the 
 side of the block to the original apron mounting holes on the saddle.
 
 And it has motors, bleeping expensive Superior Electric Slo-Syn 200 step 
 steppers. A NEMA 34 connected to the Star actuator direct drive with a 
 Lovejoy and a NEMA 23 with a belt drive to the other axis. The builder 
 for some reason put the large pulley on the motor.
 
 The table is HEAVY, made of nicely put together wood. It shall become 
 the new seat upon which my PLM2000 mill will set, after removal of 
 everything screwed down to its top. It looks deceptively weedy in the 
 photos but it's around 4 feet tall. Took three people to get it into the 
 truck and we had to tilt it up on one edge then down onto the tailgate 
 to lift and slide it in.
 
 Cost? $300 cash money. :)
 
 Some of the other parts may migrate their way into a 3D printer I'm 
 wanting to build. Need to do something with the 30 feet of 40x40mm 
 aluminum t-slot extrusion and various corner plates and angle brackets 
 I've been given.
 
 ---
 This email has been checked for viruses by Avast antivirus software.
 http://www.avast.com
 
 
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Re: [Emc-users] Velocity closed loop + Position losed loop on an axis

[Karlsson Wang]

Sounds good.


On Fri, 27 Mar 2015 20:54:31 +
andy pugh bodge...@gmail.com wrote:

 On 27 March 2015 at 20:44, Karlsson  Wang
 nicklas.karls...@karlssonwang.se wrote:
  It is possible, i can't see it anymore.
 
 As I understand it, the encoder edges are timestamped by either the
 system clock or a high-res counter in the FPGA, so at any point the
 calculation is based on the total number of edges seen and the actual
 time that the first edge seen and the last edge seen were registered.
 This allows a much more accurate calculation than just number of
 edges this servo cycle.
 
 The difference is especially marked when there are edges less often
 than once per servo thread
 
 -- 
 atp
 If you can't fix it, you don't own it.
 http://www.ifixit.com/Manifesto
 
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Re: [Emc-users] Velocity closed loop + Position losed loop on an axis

[Karlsson Wang]

It is possible, i can't see it anymore.


On Thu, 26 Mar 2015 21:46:27 +
andy pugh bodge...@gmail.com wrote:

 On 26 March 2015 at 21:10, Karlsson  Wang
 nicklas.karls...@karlssonwang.se wrote:
  Quite many pulses need to be counted and servo thread is run quite often. 
  For eight bit resolution which is rather low 256 pulses must be counted in 
  the time delta there speed is measured.
 
 I think you are misunderstanding PCW's comment.
 
 -- 
 atp
 If you can't fix it, you don't own it.
 http://www.ifixit.com/Manifesto
 
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Re: [Emc-users] Velocity closed loop + Position losed loop on an axis

[Karlsson Wang]

For stability without rattle inertia is low but for the hole gear box inertia 
is a low. I guess servo loop have to be tuned for the low inertia or a small 
load added to get rid of the rattle.

If there are enough bandwidth and computational power I can see so no reason to 
keep peridoicity of servo loop down. Theoretical upper limit then increasing 
make no point is in best twice the switching frequency. For a slow mechanical 
system there might however be very little to gain.


Nicklas Karlsson




On Wed, 25 Mar 2015 20:12:26 -0400
Gene Heskett ghesk...@wdtv.com wrote:

 On Wednesday 25 March 2015 19:02:16 Karlsson  Wang wrote:
  To get higher accuracy you need more accurate measurement, some extra
  resolution above the accuracy is also useful.
 
  For better dynamic perfomance it may make sense to close the inner
  loop if the inner loop is faster than the outer loop. If the electic
  response is much faster than the mechanical response then there is
  rather little to gain from faster control loop. If motor inductance is
  around 1mH, applied voltage is 48 volt and current is 10A then
  U=L*di/dt = dt = L*di/U = 1mH*10A/48V = 0.2ms = 200µs is the time to
  change motor torque from zero to maximum which put an upper limit on
  dynamic response, there is also a rotational speed dependent back emf
  reducing available voltage.
 
  If you do not like the math. Change servo loop peridicity adjust
  control loop and see if it make any real difference.
 
 
  Nicklas Karlsson
 
 If I can butt in here Leonardo, when I was setting up the spindle speed 
 servo in my toy lathe after switching from a non-linear and failure 
 prone driver to drive the 1hp treadmill motor my 7x12 now sports, to a 
 slightly modified version of the Pico Systems servo driver, and keeping 
 in mind I am using one of Peters 5i25 interfaces, which means I no 
 longer needed a base thread in the setup.  But the speed servo was 
 hunting badly enough to keep the back gears in the headstock rattling 
 pretty good when the servo thread was running at nominally 1 kilohertz.
 
 I had to reduce the P in the pid to the point it was essentially 
 worthless at sub 300 rev speeds.  So for SG, thinking the control was 
 too slow, I did a rockhopper diagram and re-arranged the hal file so 
 that I was doing a straight fall thru of the control path so it was not 
 wasting a period or more because it was out of order when the modules 
 were in the wrong order.  That helped but the amount of P seemed to be 
 limited yet, so the only other way to get a faster control loop was to 
 raise the servo thread speed. Nominally 2 kilohertz made an obvious 
 difference, and at 4 kilohertz, it was lots quieter.  So that is where 
 it has been running at for several months now.  P in the speed PID is 
 now high enough that I can peel off a pretty good sized string of blued 
 steel at 150 revs, or even a dimly glowing string at 500 revs, which 
 gives a more better finish.
 
 My $0.02.  Works well here, might not be worth the electron wiggle to 
 send it to someone else.  The phrase YMMV applies here.
 
 
 
 
  On Wed, 25 Mar 2015 14:45:42 -0300
 
  Leonardo Marsaglia leonardomarsagli...@gmail.com wrote:
   Hello to all!
  
   I just managed to turn the second motor of my machine (another AC
   motor with a Powerflex 40 drive) and works just fine for positioning
   the part. Tomorrow I'll be uploading some videos.
  
   Although I need to do some fine tuning on both the rotary and the
   linear axis I was thinking about a concept to improve the accuracy
   of the servo loops.
  
   As I have seen on many machines including the Mazak that we have
   here, the servo systems close the velocity loop within the servo
   drive, and then the CNC applies a voltage to control the velocity of
   the motor based on the PID of the position loop.
  
   So as I see it, it's like there is one pid nested inside the other,
   or sort of. Now the VFDs that I'm using can close the velocity loop
   but I would have to use a special module for that.
  
   My question is, based on your experience. Could this improve the
   accuracy of the joints? I guess this could be done within LinuxCNC
   without closing the loop on the VFDs.
  
   Thanks as always for your help!!
  
   --
   *Leonardo Marsaglia*.
   
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Re: [Emc-users] Velocity closed loop + Position losed loop on an axis

[Karlsson Wang]

Do the math. Accuracy is bad at low speed and there is a lower limit on speed. 
Is number of pulses counted to give speed? Is time between pulses measured to 
give speed?



Nicklas Karlsson



On Wed, 25 Mar 2015 23:59:02 -0300
Leonardo Marsaglia leonardomarsagli...@gmail.com wrote:

 2015-03-25 23:17 GMT-03:00 Jon Elson el...@pico-systems.com:
 
  You should check this out :
 
  http://wiki.linuxcnc.org/cgi-bin/wiki.pl?Combining_Two_Feedback_Devices_On_One_Axis
 
  There used to be a web page that described dual feedback on
  one of the big machines at Stuart Stevenson's MPM shop and
  had a bit of history of how they arranged to do that, but I
  can not find it now. They used a linear encoder for position
  feedback and a shaft encoder on the motor for velocity feedback.
 
  (Anybody know where the descriptive page with photos, etc.
  on that has gone to?)
 
 
 Hello Jon and thanks for the link I didn't remember about it.
 
 I guess my approach of using the same encoder mounted on the shaft of the
 motor isn't the best solution for speed and position feedback right?.
 
 As I told gene I was planning on using the same encoder for velocity and
 then position feedback but I don't know if this is a good option.
 
 
 -- 
 *Leonardo Marsaglia*.
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Re: [Emc-users] Velocity closed loop + Position losed loop on an axis

[Karlsson Wang]

Quite many pulses need to be counted and servo thread is run quite often. For 
eight bit resolution which is rather low 256 pulses must be counted in the time 
delta there speed is measured.

Nicklas Karlsson




On Thu, 26 Mar 2015 13:23:29 -0700 (PDT)
Peter C. Wallace p...@mesanet.com wrote:

 On Thu, 26 Mar 2015, Les Newell wrote:
 
  Date: Thu, 26 Mar 2015 14:00:10 +
  From: Les Newell les.new...@fastmail.co.uk
  Reply-To: Enhanced Machine Controller (EMC)
  emc-users@lists.sourceforge.net
  To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net
  Subject: Re: [Emc-users] Velocity closed loop + Position losed loop on an 
  axis
  
  Recently I used an encoder for both velocity and position on a
  specialist application (not using LinuxCNC) and it worked very well.
  Velocity is calculated by measuring the time between successive encoder
  counts. This application uses a very coarse encoder (144 counts/rev) and
  it only runs at low speed (200RPM). I'm not sure how well that would
  translate into a LinuxCNC application. For higher resolution encoders at
  higher speeds you need a very fast timer.
 
  Les
 
 
 The LinuxCNC software encoder counter and at least the Mesa and Pico Systems 
 hardware encoder counters have DeltaCounts/DeltaTime velocity estimation.
 
 This calculates the velocity based on the number of counts per servo period
 divided by the time between counts (time is measured with a high speed timer
 built into the encoder counter)
 
 You dont need a terribly fast timer because at higher speeds, you are not 
 measuring the time between single counts but rather between the first and 
 last 
 of many counts
 
 
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Re: [Emc-users] Velocity closed loop + Position losed loop on an axis

[Karlsson Wang]

To get higher accuracy you need more accurate measurement, some extra 
resolution above the accuracy is also useful.

For better dynamic perfomance it may make sense to close the inner loop if the 
inner loop is faster than the outer loop. If the electic response is much 
faster than the mechanical response then there is rather little to gain from 
faster control loop. If motor inductance is around 1mH, applied voltage is 48 
volt and current is 10A then U=L*di/dt = dt = L*di/U = 1mH*10A/48V = 0.2ms = 
200µs is the time to change motor torque from zero to maximum which put an 
upper limit on dynamic response, there is also a rotational speed dependent 
back emf reducing available voltage.

If you do not like the math. Change servo loop peridicity adjust control loop 
and see if it make any real difference.


Nicklas Karlsson





On Wed, 25 Mar 2015 14:45:42 -0300
Leonardo Marsaglia leonardomarsagli...@gmail.com wrote:

 Hello to all!
 
 I just managed to turn the second motor of my machine (another AC motor
 with a Powerflex 40 drive) and works just fine for positioning the part.
 Tomorrow I'll be uploading some videos.
 
 Although I need to do some fine tuning on both the rotary and the linear
 axis I was thinking about a concept to improve the accuracy of the servo
 loops.
 
 As I have seen on many machines including the Mazak that we have here, the
 servo systems close the velocity loop within the servo drive, and then the
 CNC applies a voltage to control the velocity of the motor based on the PID
 of the position loop.
 
 So as I see it, it's like there is one pid nested inside the other, or sort
 of. Now the VFDs that I'm using can close the velocity loop but I would
 have to use a special module for that.
 
 My question is, based on your experience. Could this improve the accuracy
 of the joints? I guess this could be done within LinuxCNC without closing
 the loop on the VFDs.
 
 Thanks as always for your help!!
 
 -- 
 *Leonardo Marsaglia*.
 --
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Re: [Emc-users] VFD causing limits to trip. Huh?

[Karlsson Wang]

The problem is there are no low impedance ground available. The mains power 
cable ground is not low impedance at high frequency and the common mode voltage 
of inverters will couple a high frequency current into the ground cable. The 
trick usually used is to isolate logical ground and increase common mode 
resistance to reduce the ground current which also will lower the high 
frequency ground voltage.

From the outside you machine have two or more power cables and one ground 
cable. There will be a capacitance between each output phase from the 
inverters and ground. This capacitance connected to ground is switched between 
the lowest and highest input voltage which of course will make a high 
frequency current flow into the high frequency non zero impedance ground.

If you connect to a star ground inside your machine they will all bounce around 
with the same voltage.

Nicklas Karlsson




On Fri, 20 Mar 2015 17:54:23 +0100
Peter Blodow p.blo...@dreki.de wrote:

 Przemek, the shield picks up stray energy from the suroundings. The 
 inside of it is a faraday cage and free of electric fields, which is 
 what we aim at. Now, as the shield has picked up the noise energy, 
 (re)converting electromagnetic field energy to real voltage and current, 
 it must get rid of it somewhere. This is most quickly done by a low 
 resistance, i.e. low impedance, shorting the noise current to ground on 
 the sending side without reaching the signal consumer.
 Sorry for answering late, I was on a short trip for the last days.
 Peter
 
 
 Am 18.03.2015 17:11, schrieb Przemek Klosowski:
  On Mon, Mar 16, 2015 at 11:34 AM, Peter Blodow p.blo...@dreki.de wrote:
  Steve,
  this is a good description of noise reduction by shielding. To make it
  more exact, the shield should be grounded at the end where the lower
  impedance is, mostly the signal source.
  This is opposite to what Steve said, which was to ground near the
  signals are consumed, which makes more sense to me because shield
  potentials, if any, have smaller chance of leaking through to the
  signal wires.
  From the impedance point of view, I would also worry more about
  interference near high-impedance nodes rather than low-impedance
  nodes, just because smal currents result in larger voltages there.
 
  Can you summarize the rationale for your recommendation in the
  language of electromagnetics?
 
 
 
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[Emc-users] Point Of Sale (POS) terminal as CNC computer

[Karlsson Wang]

Have anyone tried these POS terminals with touch screen as a CNC computer?


Nicklas Karlsson

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Re: [Emc-users] VFD causing limits to trip. Huh?

[Karlsson Wang]

I also agree about this.


Nicklas Karlsson



On Wed, 18 Mar 2015 12:43:16 -0500
Steve Stallings steve...@newsguy.com wrote:

 If one is trying to minimize radiated interference from
 a signal source, then grounding the shield at the source 
 end makes sense. 
 
 My suggestion of grounding the shield at the consumer
 of the signals was based on reducing the likelihood of
 a hostile external noise source confusing the consumer.
 
 Steve Stallings
 
  -Original Message-
  From: Przemek Klosowski [mailto:przemek.klosow...@gmail.com] 
  Sent: Wednesday, March 18, 2015 11:12 AM
  To: Enhanced Machine Controller (EMC)
  Subject: Re: [Emc-users] VFD causing limits to trip. Huh?
  
  On Mon, Mar 16, 2015 at 11:34 AM, Peter Blodow 
  p.blo...@dreki.de wrote:
   Steve,
   this is a good description of noise reduction by shielding. 
  To make it
   more exact, the shield should be grounded at the end where the lower
   impedance is, mostly the signal source.
  
  This is opposite to what Steve said, which was to ground near the
  signals are consumed, which makes more sense to me because shield
  potentials, if any, have smaller chance of leaking through to the
  signal wires.
  From the impedance point of view, I would also worry more about
  interference near high-impedance nodes rather than low-impedance
  nodes, just because smal currents result in larger voltages there.
  
  Can you summarize the rationale for your recommendation in the
  language of electromagnetics?
  
  --
  
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Re: [Emc-users] PCB adapters for oscilloscope probes

[Karlsson Wang]

It is possible to hold probe a little bit above the point, amplitude will 
however not be accurate. Rugoski coil is also useful for high frequency 
measurements of currents but not low frequency or DC.

Nicklas Karlsson




On Tue, 17 Mar 2015 22:21:45 +0100
Philipp Burch p...@hb9etc.ch wrote:

 Hi everyone,
 
 please excuse this question very unrelated to LinuxCNC, but I know that
 here are quite some people around who are familiar with scopes and
 high-frequency measurements. Some who like Tek and some who don't ;)
 
 Anyway, I've got a project where I need to measure signals with
 frequencies in the range 10Mhz .. 100Mhz without loading the driver
 itself too much (the goal is to figure out how a current control loop
 behaves at these frequencies, so I should not add much more phase lag
 just by attaching the probe). Tektronix probes of type P6158
 (http://www.tek.com/sites/tek.com/files/media/media/resources/60W_12026_2_0.pdf)
 are available, so this is ok. What we haven't a large amount of,
 however, are those PCB adapters (the ones with the four ground pins,
 where you can stick the probe vertically into). Something like this:
 http://hb9etc.ch/images/tek_probe_adapter_131-4244-00.png
 
 Now the question: Does anyone here have an idea how or where to get some
 spares of those adapters? The part# 131-4244-00 does not seem to exist
 anymore. In the probe datasheet, there is 131-5031-00 listed for those
 adapters, but market results aren't much better for those. What I found
 so far is a product on Amazon:
 http://www.amazon.com/Tektronix-131-5031-00-Tip-Probe/dp/B00DJS7BMU
 This could probably be the right thing, but $184 for 25 of those
 thingies is also quite a number. Might be worth it, but still, if anyone
 has a better idea/source/offer/whatever, please tell me.
 
 Thanks!
 
 Cheers,
 Philipp
 

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Re: [Emc-users] VFD causing limits to trip. Huh?

[Karlsson Wang]

The frequency converters I have seen for electric motors generate a square wave 
voltage. To generate a sinus the duty cycle is varied to get sinus voltage in 
average and usually the current is close to sinus.

Then it come to quality I guess the large difference is in filters and coupling 
to control signal ground. There exist true sinus output but I think all of them 
are sold as true sinus for a higher price.


Nicklas Karlsson




On Mon, 16 Mar 2015 22:19:42 +0100
Bertho Stultiens ber...@vagrearg.org wrote:

 On 03/16/2015 09:40 PM, Karlsson  Wang wrote:
  A shield is primarily intended to prevent electrostatic coupling from
  the outside world. So by grounding in the consuming end the shield
  will get the ground potential of the consumer and the signal cables
  will be shielded from different external electric fields. This should
  motivate why as you say the shield should be connected in this end
  only. If there are current there is also a potential difference.
 
 There are generally three cases to consider:
 1) a shield as a Faraday cage; this means that only one side of the
 shield may be connected to go into the earth/ground star-point where you
 maintain an absolute reference of zero (0V). The shield is used to dump
 all (most) cable-internal EM radiation into a low-impedance star-point
 via the shield.
 
 2) a shield as in a coaxial conductor; here the signal is contained in
 the cable and the shield is part of the conducting circuit. This works
 on basis of very tightly controlled cable properties and is generally
 limited to a specific frequency range per cable specs.
 
 3) all other cases; the shield is connected at both sides and is
 intentionally or unintentionally part of the conducting circuit. This
 case will generally give you worse results in terms of EMI emissions and
 protection. The shield will radiate and may act as an antenna to worsen
 the situation.
 
 
  I consider the VFD to be a noise source since it have common mode
  voltage which will emit an electrical field. There is also a
  capacitance between the VFD cables and shield. Since Shield impedance
  on high frequency is far from zero the shield around the VFD cables
  will not be at GND potential. The most common method is to increase
  common mode inductance by a filter but I have also seen active
  filters which reduce the common mode voltage and multiple step
  voltage inverters.
 
 With respect to VFD systems; the amount of junk they produce depends on
 the quality of the converter.
 
 The best version generates a relatively pure sinusoidal output and the
 EMI it generates is very minimal. Such VFD can normally be connected
 without problem with unshielded cabling.
 
 The lesser quality emulates a sinusoidal output, but has substantial
 higher harmonics. These VFDs are not too shabby, but they can cause
 interference. The best solution is to filter the output before putting
 it on (long) cables. No shielding is required when the harmonics are
 under control, but it generally does not hurt to use a Faraday cage type
 shield.
 
 The cheap VFDs are poor substitutes and generate nearing square-wave
 output. The amount of EMI from higher harmonics is high and is often
 difficult to filter at the source. These VFDs should be used with both
 output filters and shielded cabling.
 
 The remaining problem that may arise is EMI from the motor. The
 remaining harmonics may radiate from the motor just as easily. That
 cannot be solved with shielding of the cables. You must ensure proper
 earthing of the motor as well and it should be enclosed in a proper
 metal casing.
 
 It should also be noted that VFD frequency changes cause harmonics in
 the output. If you turn on/off the hard way, then you can introduce some
 transients that are very hard to control. The best way is to control the
 up-/down-going frequency such that no abrupt changes can occur and
 therefore no transients are allowed to be created due to too fast changes.
 
 -- 
 Greetings Bertho
 
 (disclaimers are disclaimed)
 
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Re: [Emc-users] VFD causing limits to trip. Huh?

[Karlsson Wang]

I think you are right and will just try to dig a little bit deeper.

A shield is primarily intended to prevent electrostatic coupling from the 
outside world. So by grounding in the consuming end the shield will get the 
ground potential of the consumer and the signal cables will be shielded from 
different external electric fields. This should motivate why as you say the 
shield should be connected in this end only. If there are current there is also 
a potential difference.

I consider the VFD to be a noise source since it have common mode voltage which 
will emit an electrical field. There is also a capacitance between the VFD 
cables and shield. Since Shield impedance on high frequency is far from zero 
the shield around the VFD cables will not be at GND potential. The most common 
method is to increase common mode inductance by a filter but I have also seen 
active filters which reduce the common mode voltage and multiple step voltage 
inverters.


Nicklas Karlsson



On Mon, 16 Mar 2015 09:41:15 -0500
Steve Stallings steve...@newsguy.com wrote:

 I would recommend that shielded signal cables have the
 shield grounded only at the end where the signals are 
 consumed. 
 
 If a ground is needed by the device at the end of the
 cable, you should use a conductor inside rather than 
 the shield itself.
 
 If there are signals going both ways, provide the shield
 ground connection at the end where the most sensitive
 signals are consumed.
 
 The purpose of grounding only one end of the shield is
 to prevent current from flowing in the shield itself and
 distorting the signals due to electromagnetic coupling.
 
 A shield is primarily intended to prevent electrostatic
 coupling from the outside world.
 
 If the cable does not contain sensitive signals, such as
 the power cable from a VFD to the spindle, then it is
 acceptable to ground both ends of the shield.
 
 Steve Stallings
 www.PMDX.com
 
 
  -Original Message-
  From: Matt Tucci [mailto:matt2c1...@gmail.com] 
  Sent: Monday, March 16, 2015 7:54 AM
  To: Enhanced Machine Controller (EMC)
  Subject: Re: [Emc-users] VFD causing limits to trip. Huh?
  
  Are the shielded wires only grounded at one end and at the 
  controller end?
  
  On Sun, Mar 15, 2015 at 1:22 PM, Karlsson  Wang 
  nicklas.karls...@karlssonwang.se wrote:
  
   I think grounding is the most important. There are normally 
  a common mode
   voltage at the inverter output to motor so the inverter 
  power ground will
   bounce around each time inverter is switched. If this 
  bouncing is coupled
   to the logic ground there may be a lot of problems.
  
   Nicklas Karlsson
  
  
  
  
   On Sun, 15 Mar 2015 14:39:24 + (GMT)
   russ...@lls.lls.com (Russell Brown) wrote:
  
   
I promised to report back so...
   
I fitted the filter (Schaffner FN2030 Series 16A 250 V ac 
  400Hz) on the
VFD mains input and that did make a difference.  My 
  failing case job ran
70% of the way through where without it the job failed 
  10% in.  Not the
complete solution though.
   
I then tried a ferrite core (mains clipon stylee) on the 
  input of the
field power supply.  No difference.  A ferrite core (ring 
  with both
wires looped through it a couple of times) on the output 
  of the 12V
field power made no difference either.
   
A ferrite core (ring as above) on the limit switch wires 
  fitted at the
Mesa end made no difference either.
   
So...  finally I replaced the limit switch wires with 
  shielded cable
(grounded only at the Mesa end).  That seemed to do the 
  final trick and
the job ran all the way through.
   
Of course I don't know if this is a 100% fix or just enough to get
through my failing case (other jobs without all the above have run
fine).  I guess time will tell.
   
Hope that's useful for someone.
   
--
 Regards,
 Russell
 
  
| Russell Brown  | MAIL: russ...@lls.com PHONE: 
  01780 471800 |
| Lady Lodge Systems | WWW Work: http://www.lls.com   
 |
| Peterborough, England  | WWW Play: 
  http://www.ruffle.me.uk |
 
  
   
   
   
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Re: [Emc-users] Ethernet!

[Karlsson Wang]

I didn't hear about RT-Net before, I read now and it looks good. If slaves 
could be implemented on ordinary micro controllers like STM32F4 there are cheap 
development boards available although with 100Mbit but not gigabit ethernet.

Nicklas Karlsson



On Sun, 15 Mar 2015 12:20:24 -0700 (PDT)
Peter C. Wallace p...@mesanet.com wrote:

 On Sun, 15 Mar 2015, Karlsson  Wang wrote:
 
  Date: Sun, 15 Mar 2015 20:03:56 +0100
  From: Karlsson  Wang nicklas.karls...@karlssonwang.se
  Reply-To: Enhanced Machine Controller (EMC)
  emc-users@lists.sourceforge.net
  To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net
  Subject: Re: [Emc-users] Ethernet!
  
  You are right, there are more bandwidth but there may be collisions. I do 
  not now about the switches but for old HUBs the full bandwidth can't be 
  used 
  because of collision and there actually is a statistical upper limit below 
  maximum capacity. Worst case delay is of course higher.
 
 There are no collisions in a real time Ethernet system, for example RT-Net 
 uses TDM so each device gets its own time slot. Ethercat allows a higher 
 update rate for situations where many devices have small amounts of data
 since it eliminates the inter-packet delays but GigE has higher useable 
 bandwidth if the amount of data is larger.
 
 
 
  For ethercat full bandwidth can be utilized without collisions even if 
  there 
  are several devices. I have chosen ethernet because I think it will be good 
  enough, it is available in almost all computers and there are cheap 
  development boards available with 100Mbit ethernet.
 
  I think Ethercat make a lot of sensors for manufacturers since there are no 
  collisions or statistics involved so they could prove the system work 
  correct but for a machine built to be used by yourself this proof is rather 
  useless.
 
 
  Nicklas Karlsson
 
 
 
  On Sun, 15 Mar 2015 10:58:38 -0700 (PDT)
  Peter C. Wallace p...@mesanet.com wrote:
 
  On Sun, 15 Mar 2015, Karlsson  Wang wrote:
 
  Date: Sun, 15 Mar 2015 18:34:13 +0100
  From: Karlsson  Wang nicklas.karls...@karlssonwang.se
  Reply-To: Enhanced Machine Controller (EMC)
  emc-users@lists.sourceforge.net
  To: Klemen Dovrtel klemen_dovr...@yahoo.com,
  Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net
  Subject: Re: [Emc-users] Ethernet!
 
  I have tried Ethernet and it works but if you connect to a switch, hub or
  similar with more devices there may of couse be real time problems. 
  Ethernet
  is cheap and readily avaiable although Ethercat I expect to be better if 
  the
  extra bandwidth is needed.
 
  Nicklas Karlsson
 
 
  Actually regular Ethernet GigE is better for bandwidth than Ethercat
  (AFAIK EtherCAT is limited to 100 mbit by current hardware)
 
 
 
 
  On Sat, 14 Mar 2015 18:09:24 + (UTC)
  Klemen Dovrtel klemen_dovr...@yahoo.com wrote:
 
   I am also interested in rt ethernet. Can you please point out which 
  instruction are these,
  RegardsKlemen
 
 
   On Friday, March 13, 2015 3:54 PM, sam sokolik 
  sa...@empirescreen.com wrote:
 
 
   I still cannot believe that it is possible.  I have been testing 2.7+
  uspace for a while now. It defiantly opens up options.
 
  Building the latest rt-preemt using peters instructions and .config made
  the latency on this laptop much much better.  I am running a 2khz servo
  thread for a day now.
 
    http://electronicsam.com/images/KandT/testing/0313150923b.jpg
 
  Realtime communication over Ethernet is just darn awesome!
 
  I would not use a laptop for normal machine running - but for developing
  systems - it sure will be nice.
 
  Thanks Peter, Micges, Jeff and everyone else that has made this a 
  reality.
 
  sam
 
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Re: [Emc-users] VFD causing limits to trip. Huh?

[Karlsson Wang]

I think grounding is the most important. There are normally a common mode 
voltage at the inverter output to motor so the inverter power ground will 
bounce around each time inverter is switched. If this bouncing is coupled to 
the logic ground there may be a lot of problems.

Nicklas Karlsson




On Sun, 15 Mar 2015 14:39:24 + (GMT)
russ...@lls.lls.com (Russell Brown) wrote:

 
 I promised to report back so...
 
 I fitted the filter (Schaffner FN2030 Series 16A 250 V ac 400Hz) on the
 VFD mains input and that did make a difference.  My failing case job ran
 70% of the way through where without it the job failed 10% in.  Not the
 complete solution though.
 
 I then tried a ferrite core (mains clipon stylee) on the input of the
 field power supply.  No difference.  A ferrite core (ring with both
 wires looped through it a couple of times) on the output of the 12V
 field power made no difference either.
 
 A ferrite core (ring as above) on the limit switch wires fitted at the
 Mesa end made no difference either.
 
 So...  finally I replaced the limit switch wires with shielded cable
 (grounded only at the Mesa end).  That seemed to do the final trick and
 the job ran all the way through.
 
 Of course I don't know if this is a 100% fix or just enough to get
 through my failing case (other jobs without all the above have run
 fine).  I guess time will tell.
 
 Hope that's useful for someone.
 
 -- 
  Regards,
  Russell
  
 | Russell Brown  | MAIL: russ...@lls.com PHONE: 01780 471800 |
 | Lady Lodge Systems | WWW Work: http://www.lls.com  |
 | Peterborough, England  | WWW Play: http://www.ruffle.me.uk |
  
 
 --
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Re: [Emc-users] Ethernet!

[Karlsson Wang]

You are right, there are more bandwidth but there may be collisions. I do not 
now about the switches but for old HUBs the full bandwidth can't be used 
because of collision and there actually is a statistical upper limit below 
maximum capacity. Worst case delay is of course higher.

For ethercat full bandwidth can be utilized without collisions even if there 
are several devices. I have chosen ethernet because I think it will be good 
enough, it is available in almost all computers and there are cheap development 
boards available with 100Mbit ethernet.

I think Ethercat make a lot of sensors for manufacturers since there are no 
collisions or statistics involved so they could prove the system work correct 
but for a machine built to be used by yourself this proof is rather useless.


Nicklas Karlsson



On Sun, 15 Mar 2015 10:58:38 -0700 (PDT)
Peter C. Wallace p...@mesanet.com wrote:

 On Sun, 15 Mar 2015, Karlsson  Wang wrote:
 
  Date: Sun, 15 Mar 2015 18:34:13 +0100
  From: Karlsson  Wang nicklas.karls...@karlssonwang.se
  Reply-To: Enhanced Machine Controller (EMC)
  emc-users@lists.sourceforge.net
  To: Klemen Dovrtel klemen_dovr...@yahoo.com,
  Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net
  Subject: Re: [Emc-users] Ethernet!
  
  I have tried Ethernet and it works but if you connect to a switch, hub or 
  similar with more devices there may of couse be real time problems. 
  Ethernet 
  is cheap and readily avaiable although Ethercat I expect to be better if 
  the 
  extra bandwidth is needed.
 
  Nicklas Karlsson
 
 
 Actually regular Ethernet GigE is better for bandwidth than Ethercat 
 (AFAIK EtherCAT is limited to 100 mbit by current hardware)
 
 
 
 
  On Sat, 14 Mar 2015 18:09:24 + (UTC)
  Klemen Dovrtel klemen_dovr...@yahoo.com wrote:
 
   I am also interested in rt ethernet. Can you please point out which 
  instruction are these,
  RegardsKlemen
 
 
   On Friday, March 13, 2015 3:54 PM, sam sokolik 
  sa...@empirescreen.com wrote:
 
 
   I still cannot believe that it is possible.  I have been testing 2.7+
  uspace for a while now. It defiantly opens up options.
 
  Building the latest rt-preemt using peters instructions and .config made
  the latency on this laptop much much better.  I am running a 2khz servo
  thread for a day now.
 
    http://electronicsam.com/images/KandT/testing/0313150923b.jpg
 
  Realtime communication over Ethernet is just darn awesome!
 
  I would not use a laptop for normal machine running - but for developing
  systems - it sure will be nice.
 
  Thanks Peter, Micges, Jeff and everyone else that has made this a reality.
 
  sam
 
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  all
  things parallel software development, from weekly thought leadership blogs 
  to
  news, videos, case studies, tutorials and more. Take a look and join the
  conversation now. http://goparallel.sourceforge.net/
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 Peter Wallace
 Mesa Electronics
 
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