Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Gene Heskett]

On Saturday 15 February 2020 06:29:08 N wrote:

> > On Friday 14 February 2020 02:01:08 andrew beck wrote:
> > > Chris.  I'm still learning electronics.  Could you expand a bit on
> > > this please.
> > >
> > > Maybe draw a napkin sketch of it.  Sorry to be a bit slow on the
> > > uptake
> >
> > I'm not Chris, but the word quadrature means two signals that change
> > state like this at a steady speed
> >
> > logic +
> > signal A, logic -
> >
> >     logic +
> > ____signal B. logic -
>
> Very common, very common and if I remember correct RS422 circuits may
> be used to decode this signal, schmitt triggered inputs might be good.

That comes std when using the $2 convertor to undifferentiate a balance 
encoder to a rail to rail ttl signal to be fed to a 5i25.
> > ...
> >
> > This type of encoder signal never skips a count even after millions
> > of direction changes. ...
>
> Well, there is usually plenty of noise in power electronics even with
> differential input signals schmitt triggered inputs might be needed.
> Checking encoder counts at zero pulse is of course a good idea.

That noise drops into the millivolt range if a single bolt ground system 
is used. Said differently in a condescending tone of voice, if you have 
more than 100 millivolts of noise anyplace you look with a scope, your 
ground system system is in need of help, probably a ground loop 
someplace. Grounding a cable shield at both ends would be a prime 
candidate.

> > And its cheap to build in hardware or software but
> > the  software version will have a speed limit much slower than the
> > hardware version, but even that can work on a smallish mill at up to
> > 30 or so inches a minute, with only a parport breakout board driving
> > the machines motors.
>
> The counter in Micro controllers usually have encoder mode for this
> purpose, it's cheap though a fast differential receiver may be more
> expensive than Micro controller but it's more because they are cheap
> and not that many dollars or whatever currency you count.
>
>
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Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[dave engvall]

partial reply to Gene's comments.

https://www.analog.com/media/en/reference-design-documentation/reference-designs/CN0276.pdf

On 2/14/20 6:20 PM, Gene Heskett wrote:

On Friday 14 February 2020 16:30:51 Andy Pugh wrote:


On 14 Feb 2020, at 20:55, Gene Heskett  wrote:

The coils are usually isolated, with op-amp bias supplied to one end
of the coils, so you get sin plus and minus and cosine + and -

I don’t think we are talking about coils here.


I was Andy, see the link Dave Engval posted to a pdf from a maker of such
that described sin/cos encoders well. I've never used one but that was a
well written tome, including the math I got lost in. What they didn't
cover to my satisfaction was how they made a single cycle per turn into
a many cycles per turn with index at the outout. Proprietary stuff
inside the IC they were discussing, and which some would call magic, and
which could result in a lag between position and output.  But thats just
a SWAG since I have zero experience with the care and feeding of such
critters.

Cheers, Gene Heskett



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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[N]

> On Friday 14 February 2020 02:01:08 andrew beck wrote:
> 
> > Chris.  I'm still learning electronics.  Could you expand a bit on
> > this please.
> >
> > Maybe draw a napkin sketch of it.  Sorry to be a bit slow on the
> > uptake
> 
> I'm not Chris, but the word quadrature means two signals that change 
> state like this at a steady speed
> 
> logic +
> signal A, logic -
> 
>     logic +
> ____signal B. logic -

Very common, very common and if I remember correct RS422 circuits may be used 
to decode this signal, schmitt triggered inputs might be good.

> ...
> 
> This type of encoder signal never skips a count even after millions of 
> direction changes. ...

Well, there is usually plenty of noise in power electronics even with 
differential input signals schmitt triggered inputs might be needed. Checking 
encoder counts at zero pulse is of course a good idea.

> And its cheap to build in hardware or software but 
> the  software version will have a speed limit much slower than the 
> hardware version, but even that can work on a smallish mill at up to 30 
> or so inches a minute, with only a parport breakout board driving the 
> machines motors.

The counter in Micro controllers usually have encoder mode for this purpose, 
it's cheap though a fast differential receiver may be more expensive than Micro 
controller but it's more because they are cheap and not that many dollars or 
whatever currency you count.


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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd --> (sin, cos) resolver

[N]

On Fri, 14 Feb 2020 08:14:18 -0800
Chris Albertson  wrote:

> Looking at the PDF, It seems I forget to ask one question about the signal:
>  Is the sin/cos signal single-ended or differential?   In other words is it
> referenced to ground or do we get pins with labels like sin+ and sin-

These kind of signals is usually used for resolvers, very common on servo 
motors, there are special chips available to excite and decode this, PGA411 is 
one. Be aware that there might be some kind of delay in signal decoding, think 
you could get a transfer function for this, if signal is 10kHz I would guess at 
least one full period is needed to track signal with good accuracy. Analog 
devices have some with 16 bit resolution per turn, expensive for an integrated 
circuit but maybe not compared to machine guess it depend on accuracy of 
machine.


Regards Nicklas Karlsson


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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[andrew beck]

Andy the EXE box looks like the right price if t will do the job.  I'll
have a look at it.  And all the data sheets etc.

Regards

Andrew

On Sat, Feb 15, 2020, 5:16 AM andy pugh  wrote:

> On Fri, 14 Feb 2020 at 15:29, dave engvall  wrote:
>
> >
> >
> >
> https://www.st.com/content/ccc/resource/technical/document/application_note/group0/6a/82/83/37/61/69/4e/74/DM00497286/files/DM00497286.pdf/jcr:content/translations/en.DM00497286.pdf
>
>
> Resolvers are a different (and slightly harder) problem as they are AC
> output.
>
> The answer almost certainly is an EXE box.
> https://www.ebay.com/itm/303373292470
> For example.
>
> But an Arduino might be a fun project to achieve the same thing.
> http://wiki.linuxcnc.org/cgi-bin/wiki.pl?ResolverToQuadratureConverter
> Is likely to get you close. You do not need any of the excitation signal
> generation code or hardware, though)
>
> --
> atp
> "A motorcycle is a bicycle with a pandemonium attachment and is designed
> for the especial use of mechanical geniuses, daredevils and lunatics."
> — George Fitch, Atlanta Constitution Newspaper, 1912
>
> ___
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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Gene Heskett]

On Friday 14 February 2020 16:30:51 Andy Pugh wrote:

> > On 14 Feb 2020, at 20:55, Gene Heskett  wrote:
> >
> > The coils are usually isolated, with op-amp bias supplied to one end
> > of the coils, so you get sin plus and minus and cosine + and -
>
> I don’t think we are talking about coils here.
>
I was Andy, see the link Dave Engval posted to a pdf from a maker of such 
that described sin/cos encoders well. I've never used one but that was a 
well written tome, including the math I got lost in. What they didn't 
cover to my satisfaction was how they made a single cycle per turn into 
a many cycles per turn with index at the outout. Proprietary stuff 
inside the IC they were discussing, and which some would call magic, and 
which could result in a lag between position and output.  But thats just 
a SWAG since I have zero experience with the care and feeding of such 
critters.

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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Andy Pugh]

> On 14 Feb 2020, at 20:55, Gene Heskett  wrote:
> 
> The coils are usually isolated, with op-amp bias supplied to one end of 
> the coils, so you get sin plus and minus and cosine + and -

I don’t think we are talking about coils here.

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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Gene Heskett]

On Friday 14 February 2020 11:14:18 Chris Albertson wrote:

> Looking at the PDF, It seems I forget to ask one question about the
> signal: Is the sin/cos signal single-ended or differential?   In other
> words is it referenced to ground or do we get pins with labels like
> sin+ and sin-

The coils are usually isolated, with op-amp bias supplied to one end of 
the coils, so you get sin plus and minus and cosine + and -

> If there are even 100 pulses per revolution and the spindle runs at
> 100K RPM then we are talking about 1K or 10 MHz.   At that point I
> start thinking about hardware quadrature decoding rather than software
> or in the Linux CNC world they use FPGA chips.

Where would one find a 100k rpm device with an encoder.

> But without understanding the signal it is way to early to even think
> about a design solution.Let's see what's on all the wires first.

IDK about resolvers but the quad in a 5i25 shouldn't have a problem with 
a quad signal at 10 MHz.

> On Fri, Feb 14, 2020 at 7:29 AM dave engvall  
wrote:
> > a bit overdone for your app but this should give you an idea. page
> > down to fig 16.
> >
> >
> > https://www.st.com/content/ccc/resource/technical/document/applicati
> >on_note/group0/6a/82/83/37/61/69/4e/74/DM00497286/files/DM00497286.pd
> >f/jcr:content/translations/en.DM00497286.pdf
> >
> > Dave
> >
> > On 2/13/20 11:01 PM, andrew beck wrote:
> > > Chris.  I'm still learning electronics.  Could you expand a bit on
> > > this please.
> > >
> > > Maybe draw a napkin sketch of it.  Sorry to be a bit slow on the
> > > uptake
> > >
> > > On Thu, Feb 13, 2020, 5:46 AM Chris Albertson
> > >  > >
> > > wrote:
> > >> A sin and cos are 90 degrees apart.  All you should need to do is
> >
> > threshold
> >
> > >> the signal and you have A/B quadrature.Many ways to threshold
> > >> it but you want the one with least noise.
> > >>
> > >> A simple way to convert a sin wave to a square wave is to amplify
> > >> then
> >
> > clip
> >
> > >> it with diodes.   A comparator can also convert the signal.
> > >>
> > >> The point to remember is that sin/cos is quadrature and all that
> > >> is
> >
> > needed
> >
> > >> is some signal conditioning.
> > >>
> > >> On Tue, Feb 11, 2020 at 10:46 PM andrew beck
> > >> 
> > >>
> > >> wrote:
> > >>> Hi guys
> > >>>
> > >>> wondering if anyone has any ideas here.
> > >>>
> > >>> I have a heidanhain spindle motor that runs up to 1 rpm and
> > >>> has a
> >
> > 5v
> >
> > >>> sin cos encoder on it.  I am currently controlling the motor
> > >>> with a schiender vfd.  I am talking to the support engineers
> > >>> here in New
> >
> > Zealand
> >
> > >>> about buying a encoder card so I can get better low down torque.
> > >>>  If I
> > >>
> > >> run
> > >>
> > >>> the card in full encoder closed loop control in the vfd I can
> > >>> get 200 percent of the torque right down to 0 rpm for 30 seconds
> > >>> or so which is pretty useful.  I am currently just running the
> > >>> drive in Variable
> > >>
> > >> frequency
> > >>
> > >>> control which rapidly looses torque at low rpm.
> > >>>
> > >>> Anyway they have a bunch of cards I can use but don't have a
> > >>> encoder
> >
> > card
> >
> > >>> that is suitable for sin cos encoders.  I have no trouble
> > >>> changing the encoder but am not sure if I can get a source of
> > >>> encoders that spin up
> >
> > to
> >
> > >>> 10k rpm.

I am spinning a $20 1000 line encoder on the rear of the spindle motor. 
That is a diff output I'm making into rail to rail sq waves with rs485 
convertors. Wide open at the motor is still 4000 edges per turn. In high 
gear the spindle makes 3k revs, 750 more than OEM. The gear ratio in the 
head in high gear is a bit over 7.1 so at 3g indicated that 4000 edges = 
something in the 70k area, which is absolutely not a problem. This is 
with the A/B coming from the motor, but the index coming from an opto 
wheel under the drawbar bolt. gear ratios determined by counting A 
signals for 100 turns of the spindle, so I use 2 different scale values 
controlled by switches on the rim of the gearshift knob. That means 
everything is accurate to a very small fraction of 1%. And it works very 
well even at Pgains that totally hide any load induced slowdown, I am 
not aware of any overload until the currant limiter in Jon's (pico 
systems) pwm-servo which is what I am driving that motor with from a 126 
volt home brewed psu that needs at least a 20 amp supply breaker.  Its 
set for around 17 amps making the iron in the motor squeak, at close to 
double that motors nameplate FLA. Don't ask why I haven't stripped the 
plastic gears in the G0704's head, I don't know and they're now nearly 5 
years old. Since that driver is a true 4 quadrant driver, I took 
advantage of the knob switches to run the motor at about 35-40 rpms when 
neither switch is closed, so when the spindle is running but in the 
wrong gear, I can reach up and change gears quite safely as when neither 
switch is closed the 

Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Chris Albertson]

Sorry.  Yes, a math error.A better estimate of the worst-case might to
20,000 RPM and 1000 pulses per rev.   That means 330,000 per second for
each channel.   But I bet close to 20,000 per second

A simple comparator with hysteresis would work well.   You really do need
to add hysteresis to deal with noise  Here is a good article:
http://www.ti.com/lit/ug/tidu020a/tidu020a.pdf

Hysteresis is a simple concept.  Every heater thermostat has this built
into it.  The "on-point" is lower than the "off-point"  otherwise the heat
would cycle to fast.

On Fri, Feb 14, 2020 at 8:25 AM andy pugh  wrote:

> On Fri, 14 Feb 2020 at 16:16, Chris Albertson 
> wrote:
>
> >
> > If there are even 100 pulses per revolution and the spindle runs at 100K
> > RPM then we are talking about 1K or 10 MHz.
> >
>
> 100,000 rpm is _very_ fast for a spindle. And even then you missed the 60
> in rpm / Hz conversion.
>
> --
> atp
> "A motorcycle is a bicycle with a pandemonium attachment and is designed
> for the especial use of mechanical geniuses, daredevils and lunatics."
> — George Fitch, Atlanta Constitution Newspaper, 1912
>
> ___
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>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[andy pugh]

On Fri, 14 Feb 2020 at 16:16, Chris Albertson 
wrote:

>
> If there are even 100 pulses per revolution and the spindle runs at 100K
> RPM then we are talking about 1K or 10 MHz.
>

100,000 rpm is _very_ fast for a spindle. And even then you missed the 60
in rpm / Hz conversion.

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912

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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Chris Albertson]

Looking at the PDF, It seems I forget to ask one question about the signal:
 Is the sin/cos signal single-ended or differential?   In other words is it
referenced to ground or do we get pins with labels like sin+ and sin-

If there are even 100 pulses per revolution and the spindle runs at 100K
RPM then we are talking about 1K or 10 MHz.   At that point I start
thinking about hardware quadrature decoding rather than software or in the
Linux CNC world they use FPGA chips.

But without understanding the signal it is way to early to even think about
a design solution.Let's see what's on all the wires first.

On Fri, Feb 14, 2020 at 7:29 AM dave engvall  wrote:

> a bit overdone for your app but this should give you an idea. page down
> to fig 16.
>
>
> https://www.st.com/content/ccc/resource/technical/document/application_note/group0/6a/82/83/37/61/69/4e/74/DM00497286/files/DM00497286.pdf/jcr:content/translations/en.DM00497286.pdf
>
> Dave
>
> On 2/13/20 11:01 PM, andrew beck wrote:
> > Chris.  I'm still learning electronics.  Could you expand a bit on this
> > please.
> >
> > Maybe draw a napkin sketch of it.  Sorry to be a bit slow on the uptake
> >
> > On Thu, Feb 13, 2020, 5:46 AM Chris Albertson  >
> > wrote:
> >
> >> A sin and cos are 90 degrees apart.  All you should need to do is
> threshold
> >> the signal and you have A/B quadrature.Many ways to threshold it but
> >> you want the one with least noise.
> >>
> >> A simple way to convert a sin wave to a square wave is to amplify then
> clip
> >> it with diodes.   A comparator can also convert the signal.
> >>
> >> The point to remember is that sin/cos is quadrature and all that is
> needed
> >> is some signal conditioning.
> >>
> >> On Tue, Feb 11, 2020 at 10:46 PM andrew beck 
> >> wrote:
> >>
> >>> Hi guys
> >>>
> >>> wondering if anyone has any ideas here.
> >>>
> >>> I have a heidanhain spindle motor that runs up to 1 rpm and has a
> 5v
> >>> sin cos encoder on it.  I am currently controlling the motor with a
> >>> schiender vfd.  I am talking to the support engineers here in New
> Zealand
> >>> about buying a encoder card so I can get better low down torque.  If I
> >> run
> >>> the card in full encoder closed loop control in the vfd I can get 200
> >>> percent of the torque right down to 0 rpm for 30 seconds or so which is
> >>> pretty useful.  I am currently just running the drive in Variable
> >> frequency
> >>> control which rapidly looses torque at low rpm.
> >>>
> >>> Anyway they have a bunch of cards I can use but don't have a encoder
> card
> >>> that is suitable for sin cos encoders.  I have no trouble changing the
> >>> encoder but am not sure if I can get a source of encoders that spin up
> to
> >>> 10k rpm.
> >>>
> >>> Anyone have any suggestions?
> >>>
> >>> regards
> >>>
> >>> Andrew
> >>>
> >>> ___
> >>> Emc-users mailing list
> >>> Emc-users@lists.sourceforge.net
> >>> https://lists.sourceforge.net/lists/listinfo/emc-users
> >>>
> >>
> >> --
> >>
> >> Chris Albertson
> >> Redondo Beach, California
> >>
> >> ___
> >> Emc-users mailing list
> >> Emc-users@lists.sourceforge.net
> >> https://lists.sourceforge.net/lists/listinfo/emc-users
> >>
> > ___
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>
>
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-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[andy pugh]

On Fri, 14 Feb 2020 at 15:29, dave engvall  wrote:

>
>
> https://www.st.com/content/ccc/resource/technical/document/application_note/group0/6a/82/83/37/61/69/4e/74/DM00497286/files/DM00497286.pdf/jcr:content/translations/en.DM00497286.pdf


Resolvers are a different (and slightly harder) problem as they are AC
output.

The answer almost certainly is an EXE box.
https://www.ebay.com/itm/303373292470
For example.

But an Arduino might be a fun project to achieve the same thing.
http://wiki.linuxcnc.org/cgi-bin/wiki.pl?ResolverToQuadratureConverter
Is likely to get you close. You do not need any of the excitation signal
generation code or hardware, though)

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912

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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[dave engvall]

a bit overdone for your app but this should give you an idea. page down 
to fig 16.


https://www.st.com/content/ccc/resource/technical/document/application_note/group0/6a/82/83/37/61/69/4e/74/DM00497286/files/DM00497286.pdf/jcr:content/translations/en.DM00497286.pdf

Dave

On 2/13/20 11:01 PM, andrew beck wrote:

Chris.  I'm still learning electronics.  Could you expand a bit on this
please.

Maybe draw a napkin sketch of it.  Sorry to be a bit slow on the uptake

On Thu, Feb 13, 2020, 5:46 AM Chris Albertson 
wrote:


A sin and cos are 90 degrees apart.  All you should need to do is threshold
the signal and you have A/B quadrature.Many ways to threshold it but
you want the one with least noise.

A simple way to convert a sin wave to a square wave is to amplify then clip
it with diodes.   A comparator can also convert the signal.

The point to remember is that sin/cos is quadrature and all that is needed
is some signal conditioning.

On Tue, Feb 11, 2020 at 10:46 PM andrew beck 
wrote:


Hi guys

wondering if anyone has any ideas here.

I have a heidanhain spindle motor that runs up to 1 rpm and has a 5v
sin cos encoder on it.  I am currently controlling the motor with a
schiender vfd.  I am talking to the support engineers here in New Zealand
about buying a encoder card so I can get better low down torque.  If I

run

the card in full encoder closed loop control in the vfd I can get 200
percent of the torque right down to 0 rpm for 30 seconds or so which is
pretty useful.  I am currently just running the drive in Variable

frequency

control which rapidly looses torque at low rpm.

Anyway they have a bunch of cards I can use but don't have a encoder card
that is suitable for sin cos encoders.  I have no trouble changing the
encoder but am not sure if I can get a source of encoders that spin up to
10k rpm.

Anyone have any suggestions?

regards

Andrew

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--

Chris Albertson
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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Gene Heskett]

On Friday 14 February 2020 07:29:53 Gene Heskett wrote:

> On Friday 14 February 2020 02:01:08 andrew beck wrote:
> > Chris.  I'm still learning electronics.  Could you expand a bit on
> > this please.
> >
> > Maybe draw a napkin sketch of it.  Sorry to be a bit slow on the
> > uptake
>
> I'm not Chris, but the word quadrature means two signals that change
> state like this at a steady speed
>
> logic +
> signal A, logic -
>
>     logic +
> ____signal B. logic -
>
> time is left to right if clockwise, or right to left if
> counterclockwise. poor ascii image of oscilloscope trace sorry.
>
> From this train of pulses coming out of the encoder the edges per time
> unit can be very accurately turned into an rpm scale to be displayed.
>
> Also the direction its moving is available at the output, freshly
> determined at the instant of any change in status of these two
> signals.
>
> Now add a 3rd signal, call it I for index, which has only a narrow
> pulse that probably is identical to just one of the above but is only
> sent by the encoder once per revolution.  This tells the decoder,
> called an encoder for some reason I don't control, that it has
> moved|turned one full turn.  linear scales may or may not have this
> last signal but rotary encoders nearly always do.  If present, this
> allows a scale to be measured and established with which you can the
> measure how far something has moved down to sub-micron accuracy.
> Applied to a spindle, it allows linuxcnc to know exactly where in its
> rotation the spindle is and that in turn allows linuxcnc to drive a
> tap into a predrilled hole, and back out at the exact pitch of the
> tap. We call that rigid tapping and taps last a lng time time
> because they are not being bent or otherwise stressed by hand tapping.
>
> There are conditions in driveing a stepper motor faster than it can
> track that same format of driving signal to the coils of a stepper,
> and keeping that slow enough the stepper can keep up becomes that
> axis's speed limit.  But thats a whole different critter and subject.
>
> This type of encoder signal never skips a count even after millions of
> direction changes.  And its cheap to build in hardware or software but
> the  software version will have a speed limit much slower than the
> hardware version, but even that can work on a smallish mill at up to
> 30 or so inches a minute, with only a parport breakout board driving
> the machines motors.

correction here, that should say "the machines motor drivers, which for 
stepper motors is normally done by step and step direction signals."

> I hope this helps explain it.  Introducing the element of time often
> causes some confusion to the idea of drawing a vertical line thru the
> above accii drawing to mark the instant of time to what happens next.
>
>
> Cheers, Gene Heskett


Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Gene Heskett]

On Friday 14 February 2020 02:01:08 andrew beck wrote:

> Chris.  I'm still learning electronics.  Could you expand a bit on
> this please.
>
> Maybe draw a napkin sketch of it.  Sorry to be a bit slow on the
> uptake

I'm not Chris, but the word quadrature means two signals that change 
state like this at a steady speed

logic +
signal A, logic -

    logic +
____signal B. logic -

time is left to right if clockwise, or right to left if counterclockwise.
poor ascii image of oscilloscope trace sorry.

>From this train of pulses coming out of the encoder the edges per time 
unit can be very accurately turned into an rpm scale to be displayed.

Also the direction its moving is available at the output, freshly 
determined at the instant of any change in status of these two signals.

Now add a 3rd signal, call it I for index, which has only a narrow pulse 
that probably is identical to just one of the above but is only sent by 
the encoder once per revolution.  This tells the decoder, called an 
encoder for some reason I don't control, that it has moved|turned one 
full turn.  linear scales may or may not have this last signal but 
rotary encoders nearly always do.  If present, this allows a scale to be 
measured and established with which you can the measure how far 
something has moved down to sub-micron accuracy. Applied to a spindle, 
it allows linuxcnc to know exactly where in its rotation the spindle is 
and that in turn allows linuxcnc to drive a tap into a predrilled hole, 
and back out at the exact pitch of the tap. We call that rigid tapping 
and taps last a lng time time because they are not being bent or 
otherwise stressed by hand tapping.

There are conditions in driveing a stepper motor faster than it can track 
that same format of driving signal to the coils of a stepper, and 
keeping that slow enough the stepper can keep up becomes that axis's 
speed limit.  But thats a whole different critter and subject.

This type of encoder signal never skips a count even after millions of 
direction changes.  And its cheap to build in hardware or software but 
the  software version will have a speed limit much slower than the 
hardware version, but even that can work on a smallish mill at up to 30 
or so inches a minute, with only a parport breakout board driving the 
machines motors.

I hope this helps explain it.  Introducing the element of time often 
causes some confusion to the idea of drawing a vertical line thru the 
above accii drawing to mark the instant of time to what happens next. 
 

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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[andrew beck]

OK I'll try track down the data sheet.  Failing that I'll borrow a
oscilloscope and have a play.  I'll post back here tomorrow

Thanks chris

Regards

Andrew

On Fri, Feb 14, 2020, 8:51 PM Chris Albertson 
wrote:

> First step is to understand (1) what you have and (2) what you need.
>
> So,  If the spindle revolves one time, How many cycles of the sin wave do
> you see?  What is the amplitude of the sine wave (in volts peak to peak)?
> Does the amplitude change with the spindle speed?You need to either
> read this information from the encoder's data sheet or measure it
>
>
> I assume you need a 5-volt square wave quadrature signal.   A potential
> problem with square wave converters is noise.   But lets first see what the
> sin wave signal looks like.
>
> On Thu, Feb 13, 2020 at 11:03 PM andrew beck 
> wrote:
>
> > Chris.  I'm still learning electronics.  Could you expand a bit on this
> > please.
> >
> > Maybe draw a napkin sketch of it.  Sorry to be a bit slow on the uptake
> >
> > On Thu, Feb 13, 2020, 5:46 AM Chris Albertson  >
> > wrote:
> >
> > > A sin and cos are 90 degrees apart.  All you should need to do is
> > threshold
> > > the signal and you have A/B quadrature.Many ways to threshold it
> but
> > > you want the one with least noise.
> > >
> > > A simple way to convert a sin wave to a square wave is to amplify then
> > clip
> > > it with diodes.   A comparator can also convert the signal.
> > >
> > > The point to remember is that sin/cos is quadrature and all that is
> > needed
> > > is some signal conditioning.
> > >
> > > On Tue, Feb 11, 2020 at 10:46 PM andrew beck  >
> > > wrote:
> > >
> > > > Hi guys
> > > >
> > > > wondering if anyone has any ideas here.
> > > >
> > > > I have a heidanhain spindle motor that runs up to 1 rpm and has a
> > 5v
> > > > sin cos encoder on it.  I am currently controlling the motor with a
> > > > schiender vfd.  I am talking to the support engineers here in New
> > Zealand
> > > > about buying a encoder card so I can get better low down torque.  If
> I
> > > run
> > > > the card in full encoder closed loop control in the vfd I can get 200
> > > > percent of the torque right down to 0 rpm for 30 seconds or so which
> is
> > > > pretty useful.  I am currently just running the drive in Variable
> > > frequency
> > > > control which rapidly looses torque at low rpm.
> > > >
> > > > Anyway they have a bunch of cards I can use but don't have a encoder
> > card
> > > > that is suitable for sin cos encoders.  I have no trouble changing
> the
> > > > encoder but am not sure if I can get a source of encoders that spin
> up
> > to
> > > > 10k rpm.
> > > >
> > > > Anyone have any suggestions?
> > > >
> > > > regards
> > > >
> > > > Andrew
> > > >
> > > > ___
> > > > Emc-users mailing list
> > > > Emc-users@lists.sourceforge.net
> > > > https://lists.sourceforge.net/lists/listinfo/emc-users
> > > >
> > >
> > >
> > > --
> > >
> > > Chris Albertson
> > > Redondo Beach, California
> > >
> > > ___
> > > Emc-users mailing list
> > > Emc-users@lists.sourceforge.net
> > > https://lists.sourceforge.net/lists/listinfo/emc-users
> > >
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
>
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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Chris Albertson]

First step is to understand (1) what you have and (2) what you need.

So,  If the spindle revolves one time, How many cycles of the sin wave do
you see?  What is the amplitude of the sine wave (in volts peak to peak)?
Does the amplitude change with the spindle speed?You need to either
read this information from the encoder's data sheet or measure it


I assume you need a 5-volt square wave quadrature signal.   A potential
problem with square wave converters is noise.   But lets first see what the
sin wave signal looks like.

On Thu, Feb 13, 2020 at 11:03 PM andrew beck 
wrote:

> Chris.  I'm still learning electronics.  Could you expand a bit on this
> please.
>
> Maybe draw a napkin sketch of it.  Sorry to be a bit slow on the uptake
>
> On Thu, Feb 13, 2020, 5:46 AM Chris Albertson 
> wrote:
>
> > A sin and cos are 90 degrees apart.  All you should need to do is
> threshold
> > the signal and you have A/B quadrature.Many ways to threshold it but
> > you want the one with least noise.
> >
> > A simple way to convert a sin wave to a square wave is to amplify then
> clip
> > it with diodes.   A comparator can also convert the signal.
> >
> > The point to remember is that sin/cos is quadrature and all that is
> needed
> > is some signal conditioning.
> >
> > On Tue, Feb 11, 2020 at 10:46 PM andrew beck 
> > wrote:
> >
> > > Hi guys
> > >
> > > wondering if anyone has any ideas here.
> > >
> > > I have a heidanhain spindle motor that runs up to 1 rpm and has a
> 5v
> > > sin cos encoder on it.  I am currently controlling the motor with a
> > > schiender vfd.  I am talking to the support engineers here in New
> Zealand
> > > about buying a encoder card so I can get better low down torque.  If I
> > run
> > > the card in full encoder closed loop control in the vfd I can get 200
> > > percent of the torque right down to 0 rpm for 30 seconds or so which is
> > > pretty useful.  I am currently just running the drive in Variable
> > frequency
> > > control which rapidly looses torque at low rpm.
> > >
> > > Anyway they have a bunch of cards I can use but don't have a encoder
> card
> > > that is suitable for sin cos encoders.  I have no trouble changing the
> > > encoder but am not sure if I can get a source of encoders that spin up
> to
> > > 10k rpm.
> > >
> > > Anyone have any suggestions?
> > >
> > > regards
> > >
> > > Andrew
> > >
> > > ___
> > > Emc-users mailing list
> > > Emc-users@lists.sourceforge.net
> > > https://lists.sourceforge.net/lists/listinfo/emc-users
> > >
> >
> >
> > --
> >
> > Chris Albertson
> > Redondo Beach, California
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
>
> ___
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> https://lists.sourceforge.net/lists/listinfo/emc-users
>


-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[andrew beck]

Chris.  I'm still learning electronics.  Could you expand a bit on this
please.

Maybe draw a napkin sketch of it.  Sorry to be a bit slow on the uptake

On Thu, Feb 13, 2020, 5:46 AM Chris Albertson 
wrote:

> A sin and cos are 90 degrees apart.  All you should need to do is threshold
> the signal and you have A/B quadrature.Many ways to threshold it but
> you want the one with least noise.
>
> A simple way to convert a sin wave to a square wave is to amplify then clip
> it with diodes.   A comparator can also convert the signal.
>
> The point to remember is that sin/cos is quadrature and all that is needed
> is some signal conditioning.
>
> On Tue, Feb 11, 2020 at 10:46 PM andrew beck 
> wrote:
>
> > Hi guys
> >
> > wondering if anyone has any ideas here.
> >
> > I have a heidanhain spindle motor that runs up to 1 rpm and has a 5v
> > sin cos encoder on it.  I am currently controlling the motor with a
> > schiender vfd.  I am talking to the support engineers here in New Zealand
> > about buying a encoder card so I can get better low down torque.  If I
> run
> > the card in full encoder closed loop control in the vfd I can get 200
> > percent of the torque right down to 0 rpm for 30 seconds or so which is
> > pretty useful.  I am currently just running the drive in Variable
> frequency
> > control which rapidly looses torque at low rpm.
> >
> > Anyway they have a bunch of cards I can use but don't have a encoder card
> > that is suitable for sin cos encoders.  I have no trouble changing the
> > encoder but am not sure if I can get a source of encoders that spin up to
> > 10k rpm.
> >
> > Anyone have any suggestions?
> >
> > regards
> >
> > Andrew
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users
> >
>
>
> --
>
> Chris Albertson
> Redondo Beach, California
>
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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Eric Keller]

my understanding is that most sin/cos are many lines per rev.  It's just
that they are fancier lines than an encoder made for incremental output.
The index marker is one line per rev.

On Wed, Feb 12, 2020 at 1:25 PM Gene Heskett  wrote:

> On Wednesday 12 February 2020 11:43:52 Chris Albertson wrote:
>
> > A sin and cos are 90 degrees apart.  All you should need to do is
> > threshold the signal and you have A/B quadrature.Many ways to
> > threshold it but you want the one with least noise.
> >
> > A simple way to convert a sin wave to a square wave is to amplify then
> > clip it with diodes.   A comparator can also convert the signal.
> >
> > The point to remember is that sin/cos is quadrature and all that is
> > needed is some signal conditioning.
> >
> But the sin/cos is generally per rev or at best a small multiplier. So
> positional accuracy is obtained by some fawncy math converting the
> waveforms into degrees. Which usually involves some math and therefore
> lag. A 1000 line (or more) quadrature encoder can give you the info your
> PID wants much faster. Meaning you can use Pgain by the bucketfull. I am
> doing that in fact.
>
> In a pinch, one should not forget that a small stepper motor can make a
> good encoder driver by feeding its coils thru a high r buildout resistor
> in each wire, to a dual comparator setup for just enough historesis(sp?)
> to keep it quiet when stopped. An excellent jog dial can be constructed
> from old floppy drive step motors, very useable where you don't need an
> index pulse. Just feed the comparator output to an A/B quad decoder.
>
> Someplace in my midden heap I have box with 4 motors in it and some
> LM339's that I am going to finish a 4 axis jog pendent for my G0704. But
> I ran out of encoder inputs in my interface. A 5i25/7i76 plus a std bob.
> Thats only 2 decoders.
>
> And I'd also done away with the base thread, so no real way to use
> software encoders AND get real speeds. I could switch the 7i76 and bob
> out for a pair of 7i90's and a 6 pack of 7i42TA's but that would be both
> overkill and $400+.  What would I do with another 100 gpio's after I
> made all that work? Boggles what little mind I have left...
>
> > On Tue, Feb 11, 2020 at 10:46 PM andrew beck
> > 
> >
> > wrote:
> > > Hi guys
> > >
> > > wondering if anyone has any ideas here.
> > >
> > > I have a heidanhain spindle motor that runs up to 1 rpm and has
> > > a 5v sin cos encoder on it.  I am currently controlling the motor
> > > with a schiender vfd.  I am talking to the support engineers here in
> > > New Zealand about buying a encoder card so I can get better low down
> > > torque.  If I run the card in full encoder closed loop control in
> > > the vfd I can get 200 percent of the torque right down to 0 rpm for
> > > 30 seconds or so which is pretty useful.  I am currently just
> > > running the drive in Variable frequency control which rapidly looses
> > > torque at low rpm.
> > >
> > > Anyway they have a bunch of cards I can use but don't have a encoder
> > > card that is suitable for sin cos encoders.  I have no trouble
> > > changing the encoder but am not sure if I can get a source of
> > > encoders that spin up to 10k rpm.
> > >
> > > Anyone have any suggestions?
> > >
> > > regards
> > >
> > > Andrew
> > >
> > > ___
> > > Emc-users mailing list
> > > Emc-users@lists.sourceforge.net
> > > https://lists.sourceforge.net/lists/listinfo/emc-users
>
>
> 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)
> If we desire respect for the law, we must first make the law respectable.
>  - Louis D. Brandeis
> Genes Web page 
>
>
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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[andy pugh]

On Wed, 12 Feb 2020 at 06:46, andrew beck  wrote:

>
> wondering if anyone has any ideas here.


Just to add to the mix, I have done this with an Arduino.
In my application I was also generating the excitation voltage for a
resolver, so it was a little more involved.

Fundamentally it is two analogue reads and an atan2()

-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912

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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Gene Heskett]

On Wednesday 12 February 2020 11:43:52 Chris Albertson wrote:

> A sin and cos are 90 degrees apart.  All you should need to do is
> threshold the signal and you have A/B quadrature.Many ways to
> threshold it but you want the one with least noise.
>
> A simple way to convert a sin wave to a square wave is to amplify then
> clip it with diodes.   A comparator can also convert the signal.
>
> The point to remember is that sin/cos is quadrature and all that is
> needed is some signal conditioning.
>
But the sin/cos is generally per rev or at best a small multiplier. So 
positional accuracy is obtained by some fawncy math converting the 
waveforms into degrees. Which usually involves some math and therefore 
lag. A 1000 line (or more) quadrature encoder can give you the info your 
PID wants much faster. Meaning you can use Pgain by the bucketfull. I am 
doing that in fact.

In a pinch, one should not forget that a small stepper motor can make a 
good encoder driver by feeding its coils thru a high r buildout resistor 
in each wire, to a dual comparator setup for just enough historesis(sp?) 
to keep it quiet when stopped. An excellent jog dial can be constructed 
from old floppy drive step motors, very useable where you don't need an 
index pulse. Just feed the comparator output to an A/B quad decoder.

Someplace in my midden heap I have box with 4 motors in it and some 
LM339's that I am going to finish a 4 axis jog pendent for my G0704. But 
I ran out of encoder inputs in my interface. A 5i25/7i76 plus a std bob. 
Thats only 2 decoders.  

And I'd also done away with the base thread, so no real way to use 
software encoders AND get real speeds. I could switch the 7i76 and bob 
out for a pair of 7i90's and a 6 pack of 7i42TA's but that would be both 
overkill and $400+.  What would I do with another 100 gpio's after I 
made all that work? Boggles what little mind I have left...

> On Tue, Feb 11, 2020 at 10:46 PM andrew beck
> 
>
> wrote:
> > Hi guys
> >
> > wondering if anyone has any ideas here.
> >
> > I have a heidanhain spindle motor that runs up to 1 rpm and has
> > a 5v sin cos encoder on it.  I am currently controlling the motor
> > with a schiender vfd.  I am talking to the support engineers here in
> > New Zealand about buying a encoder card so I can get better low down
> > torque.  If I run the card in full encoder closed loop control in
> > the vfd I can get 200 percent of the torque right down to 0 rpm for
> > 30 seconds or so which is pretty useful.  I am currently just
> > running the drive in Variable frequency control which rapidly looses
> > torque at low rpm.
> >
> > Anyway they have a bunch of cards I can use but don't have a encoder
> > card that is suitable for sin cos encoders.  I have no trouble
> > changing the encoder but am not sure if I can get a source of
> > encoders that spin up to 10k rpm.
> >
> > Anyone have any suggestions?
> >
> > regards
> >
> > Andrew
> >
> > ___
> > Emc-users mailing list
> > Emc-users@lists.sourceforge.net
> > https://lists.sourceforge.net/lists/listinfo/emc-users


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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Thomas J Powderly]

Jon, I cant find US dist either

maybe the TI chips are better is the states

http://www.ti.com/lit/ug/tidua05a/tidua05a.pdf
http://www.ti.com/lit/df/tidrf54/tidrf54.pdf

hth

tomP




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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Jon Elson]

On 02/12/2020 05:21 AM, Thomas J Powderly wrote:

hello

BTW if your encoder is 11uA ( not 5V not 1Vp/p )

then the last diagram here may be of use

http://pdf.dzsc.com/RLX/RLXA2510.pdf


Hey, this is a GREAT chip!  But, can you actually buy them?  
All I see are Russia and AliBaba, no US distributors.


Thanks,

Jon



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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Jon Elson]

On 02/12/2020 12:43 AM, andrew beck wrote:

Hi guys

wondering if anyone has any ideas here.

I have a heidanhain spindle motor that runs up to 1 rpm and has a 5v
sin cos encoder on it.  I am currently controlling the motor with a
schiender vfd.  I am talking to the support engineers here in New Zealand
about buying a encoder card so I can get better low down torque.  If I run
the card in full encoder closed loop control in the vfd I can get 200
percent of the torque right down to 0 rpm for 30 seconds or so which is
pretty useful.  I am currently just running the drive in Variable frequency
control which rapidly looses torque at low rpm.

Anyway they have a bunch of cards I can use but don't have a encoder card
that is suitable for sin cos encoders.  I have no trouble changing the
encoder but am not sure if I can get a source of encoders that spin up to
10k rpm.


Is this a current-output encoder or a voltage-output one? 
Heidenhain makes both.  For current-output,
average current is 11 uA or so.  So, you can run that 
current into a 1K resistor and get 11 mV.
Feed it into a comparator with the other input set to 5.5 mV 
and you should get a nice square wave.
Adjust the threshold voltage to get a 50% square wave and 
you are done.  You probably need
3 of these circuits to handle A, B and Z, if provided.  If 
not, then you need something a little more

tricky if you want a spindle index signal.

If this is too noisy, change the 1K resistor to 10 K, then 
you will get 110 mV output, and up your threshold to 55 mV.


If the encoder is voltage-output, then you just get rid of 
the resistor.


How many "pulses" does the encoder have?  Just one?  I hope 
not, that would make this scheme not
work well.  Then, interpolation would be required.  But, I 
can't imagine how to make a reliable optical encoder

with just one pulse/rev.

Jon


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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Chris Albertson]

A sin and cos are 90 degrees apart.  All you should need to do is threshold
the signal and you have A/B quadrature.Many ways to threshold it but
you want the one with least noise.

A simple way to convert a sin wave to a square wave is to amplify then clip
it with diodes.   A comparator can also convert the signal.

The point to remember is that sin/cos is quadrature and all that is needed
is some signal conditioning.

On Tue, Feb 11, 2020 at 10:46 PM andrew beck 
wrote:

> Hi guys
>
> wondering if anyone has any ideas here.
>
> I have a heidanhain spindle motor that runs up to 1 rpm and has a 5v
> sin cos encoder on it.  I am currently controlling the motor with a
> schiender vfd.  I am talking to the support engineers here in New Zealand
> about buying a encoder card so I can get better low down torque.  If I run
> the card in full encoder closed loop control in the vfd I can get 200
> percent of the torque right down to 0 rpm for 30 seconds or so which is
> pretty useful.  I am currently just running the drive in Variable frequency
> control which rapidly looses torque at low rpm.
>
> Anyway they have a bunch of cards I can use but don't have a encoder card
> that is suitable for sin cos encoders.  I have no trouble changing the
> encoder but am not sure if I can get a source of encoders that spin up to
> 10k rpm.
>
> Anyone have any suggestions?
>
> regards
>
> Andrew
>
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-- 

Chris Albertson
Redondo Beach, California

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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Thomas J Powderly]

gene,

On 2/12/20 10:38 PM, Gene Heskett wrote:

On Wednesday 12 February 2020 05:55:34 you wrote:
...

so make sure you know the full heidenhain part number when hunting
info

that means the full identifier is more than just 1 box on the label )

Yes, I've noted the frustration creation of finding info on the
Heidenhain encoders on the list over the years. Enough that I'd be
reticent to buy them as they seem to have a random number generator in
naming them.



hahaha gene,

its really simple once you read the book "howto identify that heidenhain 
thingy."


or ask a Heidenhain.

I think there's a lot of stuff posted to inet and ebay etc with 
serialnumbers as identifiers


tomp

here's the skinny on the id label

you need the product name and identity number

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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[dave engvall]

Check the max frequency on any encoder you look at. The inexpensive ones 
max out at 200 K. Frequency is not a problem is you want to throw $$ at 
it. It is very hard to win; lots of counts at the high end but not many 
when you are creeping. There just ain't no free lunch.


Dave


On 2/11/20 10:43 PM, andrew beck wrote:

Hi guys

wondering if anyone has any ideas here.

I have a heidanhain spindle motor that runs up to 1 rpm and has a 5v
sin cos encoder on it.  I am currently controlling the motor with a
schiender vfd.  I am talking to the support engineers here in New Zealand
about buying a encoder card so I can get better low down torque.  If I run
the card in full encoder closed loop control in the vfd I can get 200
percent of the torque right down to 0 rpm for 30 seconds or so which is
pretty useful.  I am currently just running the drive in Variable frequency
control which rapidly looses torque at low rpm.

Anyway they have a bunch of cards I can use but don't have a encoder card
that is suitable for sin cos encoders.  I have no trouble changing the
encoder but am not sure if I can get a source of encoders that spin up to
10k rpm.

Anyone have any suggestions?

regards

Andrew

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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[dave engvall]

http://pico-systems.com/osc2.5/catalog/product_info.php?products_id=31=2n4hbnn63oqt9ncdlervb08tv6


On 2/12/20 1:52 AM, Gene Heskett wrote:

On Wednesday 12 February 2020 01:49:34 andrew beck wrote:


the option I just thought of while googling is, can I convert the sin
cos format in to a normal TTL or something like that?  even 1000 ppr
would be heaps it is only on the spindle.

One thing you might try, is to use a couple of those $2 rs485 to ttl
boards. I bought an encoder to put on the rear of the spindle motor,
only to find on its arrival it had a balanced output of only a few
millivolts, nothing ttl about it.  So I made a small hammond box with
two of those in it to translate it to ttl for feeding the encoder in the
5i25.  Works a treat.  But because the sin/cos is generally magneticly
generated, its signal may get weak enough to miss count at very low
speeds, which might lead to enough error to make sloppy threads when
rigid tapping with a peck routine. It might miscount at the turnaround
at the bottom of the hole.


I just want to get the data into the vfd so It knows when the motors
is slowing down.  and so I can rigid tap and the existing encoder is a
high quality heidenhian one so might be good to keep it if it is not
too much trouble.

ISTR Jon has a board for that, see at PicoSystems.com.


regards

Andrew

On Wed, Feb 12, 2020 at 7:43 PM andrew beck 

wrote:

Hi guys

wondering if anyone has any ideas here.

I have a heidanhain spindle motor that runs up to 1 rpm and has
a 5v sin cos encoder on it.  I am currently controlling the motor
with a schiender vfd.  I am talking to the support engineers here in
New Zealand about buying a encoder card so I can get better low down
torque.  If I run the card in full encoder closed loop control in
the vfd I can get 200 percent of the torque right down to 0 rpm for
30 seconds or so which is pretty useful.  I am currently just
running the drive in Variable frequency control which rapidly looses
torque at low rpm.

Anyway they have a bunch of cards I can use but don't have a encoder
card that is suitable for sin cos encoders.  I have no trouble
changing the encoder but am not sure if I can get a source of
encoders that spin up to 10k rpm.

Anyone have any suggestions?

regards

Andrew

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Cheers, Gene Heskett



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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[andy pugh]

On Wed, 12 Feb 2020 at 06:46, andrew beck  wrote:

I have a heidanhain spindle motor that runs up to 1 rpm and has a 5v
> sin cos encoder on it.
>

Try looking on eBay for a Heidenhain EXE box. (Though I am not sure that
they work with 5V sin/cos)


-- 
atp
"A motorcycle is a bicycle with a pandemonium attachment and is designed
for the especial use of mechanical geniuses, daredevils and lunatics."
— George Fitch, Atlanta Constitution Newspaper, 1912

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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Eric Keller]

I think the 5v are newer than the ones I have researched in the past.
Don't they have a converter card for ttl/quadrature? They certainly do for
the older types. People seem to have used the TIDA-00178 converter board.


On Wed, Feb 12, 2020 at 1:46 AM andrew beck 
wrote:

> Hi guys
>
> wondering if anyone has any ideas here.
>
> I have a heidanhain spindle motor that runs up to 1 rpm and has a 5v
> sin cos encoder on it.  I am currently controlling the motor with a
> schiender vfd.  I am talking to the support engineers here in New Zealand
> about buying a encoder card so I can get better low down torque.  If I run
> the card in full encoder closed loop control in the vfd I can get 200
> percent of the torque right down to 0 rpm for 30 seconds or so which is
> pretty useful.  I am currently just running the drive in Variable frequency
> control which rapidly looses torque at low rpm.
>
> Anyway they have a bunch of cards I can use but don't have a encoder card
> that is suitable for sin cos encoders.  I have no trouble changing the
> encoder but am not sure if I can get a source of encoders that spin up to
> 10k rpm.
>
> Anyone have any suggestions?
>
> regards
>
> Andrew
>
> ___
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> Emc-users@lists.sourceforge.net
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>

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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Thomas J Powderly]

hello

BTW if your encoder is 11uA ( not 5V not 1Vp/p )

then the last diagram here may be of use

http://pdf.dzsc.com/RLX/RLXA2510.pdf


heidenhain encoders are good equipment, it'd be sad to change it out.

hth tomp



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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Gene Heskett]

On Wednesday 12 February 2020 01:49:34 andrew beck wrote:

> the option I just thought of while googling is, can I convert the sin
> cos format in to a normal TTL or something like that?  even 1000 ppr
> would be heaps it is only on the spindle.

One thing you might try, is to use a couple of those $2 rs485 to ttl 
boards. I bought an encoder to put on the rear of the spindle motor, 
only to find on its arrival it had a balanced output of only a few 
millivolts, nothing ttl about it.  So I made a small hammond box with 
two of those in it to translate it to ttl for feeding the encoder in the 
5i25.  Works a treat.  But because the sin/cos is generally magneticly 
generated, its signal may get weak enough to miss count at very low 
speeds, which might lead to enough error to make sloppy threads when 
rigid tapping with a peck routine. It might miscount at the turnaround 
at the bottom of the hole.

> I just want to get the data into the vfd so It knows when the motors
> is slowing down.  and so I can rigid tap and the existing encoder is a
> high quality heidenhian one so might be good to keep it if it is not
> too much trouble.

ISTR Jon has a board for that, see at PicoSystems.com.

> regards
>
> Andrew
>
> On Wed, Feb 12, 2020 at 7:43 PM andrew beck 
>
> wrote:
> > Hi guys
> >
> > wondering if anyone has any ideas here.
> >
> > I have a heidanhain spindle motor that runs up to 1 rpm and has
> > a 5v sin cos encoder on it.  I am currently controlling the motor
> > with a schiender vfd.  I am talking to the support engineers here in
> > New Zealand about buying a encoder card so I can get better low down
> > torque.  If I run the card in full encoder closed loop control in
> > the vfd I can get 200 percent of the torque right down to 0 rpm for
> > 30 seconds or so which is pretty useful.  I am currently just
> > running the drive in Variable frequency control which rapidly looses
> > torque at low rpm.
> >
> > Anyway they have a bunch of cards I can use but don't have a encoder
> > card that is suitable for sin cos encoders.  I have no trouble
> > changing the encoder but am not sure if I can get a source of
> > encoders that spin up to 10k rpm.
> >
> > Anyone have any suggestions?
> >
> > regards
> >
> > Andrew
>
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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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[Gene Heskett]

On Wednesday 12 February 2020 01:43:33 andrew beck wrote:

> Hi guys
>
> wondering if anyone has any ideas here.
>
> I have a heidanhain spindle motor that runs up to 1 rpm and has a
> 5v sin cos encoder on it.  I am currently controlling the motor with a
> schiender vfd.  I am talking to the support engineers here in New
> Zealand about buying a encoder card so I can get better low down
> torque.  If I run the card in full encoder closed loop control in the
> vfd I can get 200 percent of the torque right down to 0 rpm for 30
> seconds or so which is pretty useful.  I am currently just running the
> drive in Variable frequency control which rapidly looses torque at low
> rpm.
>
> Anyway they have a bunch of cards I can use but don't have a encoder
> card that is suitable for sin cos encoders.  I have no trouble
> changing the encoder but am not sure if I can get a source of encoders
> that spin up to 10k rpm.
>
> Anyone have any suggestions?

I have an encoder, not a sin/cos, but an A/B/Z quadrature on my Sheldon 
lathes bull gear. I because the vfd is pretty stiff, haven't even a PID 
in its circuit.  But by programming my 1.5 hp rated clone vfd to fit the 
motor, specifically to boost the low frequencies but limited to the 
nameplate FLA amps, can run a 1hp 3 phase down to 5hz while cutting 
steel for long enough to get the job done, nearly an hour in one 
instance while still being able to lay a hand on the motor at the end of 
the job. And the encoder there is only used for threading, including 
rigid tapping.

I bought a 6040 gantry machine a year ago, it all ran on 120 volts, but 
the electronics were junk, so I junked them and fitted new. Including 
locating a 120 volt clone vfd, whose manual was somewhat less than 
useful, and it took a months worth of experimentation to find the 
registers that controlled that, but I did finally get that water cooled 
24k motor to turn 500 revs while plowing a 1/8" mill thru 1/8" of alu 
with mister coolant. No encoder on/in that motor. So it will never do 
rigid tapping. I have dreams of carving gunstocks with it eventually.

Generally speaking, the slip angle of hz vs speed seems to be a fixed 
thing depending on the coil current the vfd can get into the motor, up 
to the motors FLA, What currant you can get at the higher speeds is 
limited by the coils inductance, so by the time its up to 200hz on the 
lathe, coil current is under an amp and the slip angle becomes quite 
large, to the point where an increase in the hz isn't matched by an 
actual increase in the motor rpms. That particular motor came off a 50 
yo air compressor, so its first intro to a vfd was when I hooked it up 
about 4 years ago after putting fresh bearings in it.  Definitely NOT an 
inverter rated motor, but it still gets the job done.
 
What I'm saying is that due to the slip angles at low speed, unless the 
vfd is properly programmed, low speed torque is far more a function of 
vfd programming than it will be obtained by putting the vfd's hz under 
PID control. If the excitation current isn't there, neither will the 
available torque to maintain the desired speed. 

For water cooled 24k motors it can be educational to stick an lcd 
thermometer on the side of the coolant tank although a 4 gallon tank 
takes a while to respond.

So can an amprobe on a motor leg. Getting the low speed boost up to 
nameplate FLA will be much more helpfull than the encoder feedback.  And 
beware of amprobes that lie like a rug at low frequencies, one of mine 
shows half the current actually passing at 30 hz.  Its a 50 yo genuine 
Amprobe. Only accurate at 60 hz.

Check it with an auto headlamp possibly with a shunting R in series with 
a motor coil, its brightness will NOT lie to you like the amprobes can. 
But its uncalibrated at any hz, so if in doubt. check its brightness at 
60 hz, and the correct currant, then maintain that brightness as the 
hertz goes down. You are then actually delivering the same current if 
the headlamp is the same brightness.

HTH Andrew.

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)
If we desire respect for the law, we must first make the law respectable.
 - Louis D. Brandeis
Genes Web page 


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Re: [Emc-users] trying to connect a encoder from cnc spindle motor to schiender vfd

[andrew beck]

the option I just thought of while googling is, can I convert the sin cos
format in to a normal TTL or something like that?  even 1000 ppr would be
heaps it is only on the spindle.

I just want to get the data into the vfd so It knows when the motors is
slowing down.  and so I can rigid tap and the existing encoder is a high
quality heidenhian one so might be good to keep it if it is not too
much trouble.

regards

Andrew

On Wed, Feb 12, 2020 at 7:43 PM andrew beck 
wrote:

> Hi guys
>
> wondering if anyone has any ideas here.
>
> I have a heidanhain spindle motor that runs up to 1 rpm and has a 5v
> sin cos encoder on it.  I am currently controlling the motor with a
> schiender vfd.  I am talking to the support engineers here in New Zealand
> about buying a encoder card so I can get better low down torque.  If I run
> the card in full encoder closed loop control in the vfd I can get 200
> percent of the torque right down to 0 rpm for 30 seconds or so which is
> pretty useful.  I am currently just running the drive in Variable frequency
> control which rapidly looses torque at low rpm.
>
> Anyway they have a bunch of cards I can use but don't have a encoder card
> that is suitable for sin cos encoders.  I have no trouble changing the
> encoder but am not sure if I can get a source of encoders that spin up to
> 10k rpm.
>
> Anyone have any suggestions?
>
> regards
>
> Andrew
>

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