subject:"\[Emc\-users\] Modbus"

> > > > ISO7421
> > >
> > > Now thats sweet, and a heck of a lot better thought out than the
> > > last such chip I looked at a decade ago.  Needs a 4 wire cable from
> > > each direction, but I don't see as that as a problem other than
> > > stealing the ground and  3.3 or 5 volts to run its side of it at
> > > both ends.
> > >
> > > That should indeed sove the noise problem.  The pcb requires a
> > > slightly different layout of putting the power on the center layers,
> > > so the best bet is to look around and see if someone might have it
> > > all boxed up and ready to connect.
> > >
> > > Were you able to find such a ready-made critter?  If so where?
> >
> > No I made my own circuit board, two layer. SO footprint should not be
> > to hard to solder there are small prototype boards or similar on
> > Farnell.
> >
> > http://se.farnell.com/roth-elektronik/re932-01/pcb-adaptor-smd-so-8-20
> >-5mmx8mm/dp/1426169
> > http://se.farnell.com/roth-elektronik/re932-03/adaptor-smd-so-14-1-27m
> >m/dp/1426171
> > http://se.farnell.com/roth-elektronik/re932-02/adaptor-smd-so-8w-1-27m
> >m/dp/1426170
> > http://se.farnell.com/roth-elektronik/re932-01st/multi-adapter-11-5x16
> >mm-soic-8/dp/2292022
> >
> > I do not have time to check if footprint is correct.
> >
> Immaterial as you wouls wire to suit, but all of them are missing a place 
> to put the recommended supply rail bypassing. And extra plated thru-hole 
> in each runner to the terminal would be nice.
> 
> But who is Farnell on this "west side" of the pond?  Or are they even 
> affiliated with anybody in the US?

Maybe it is newark http://www.newark.com/ otherwise I think digikey may be 
closer to you.

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Re: [Emc-users] Modbus wiring

On Sunday 03 April 2016 18:12:28 Nicklas Karlsson wrote:

> > > ISO7421
> >
> > Now thats sweet, and a heck of a lot better thought out than the
> > last such chip I looked at a decade ago.  Needs a 4 wire cable from
> > each direction, but I don't see as that as a problem other than
> > stealing the ground and  3.3 or 5 volts to run its side of it at
> > both ends.
> >
> > That should indeed sove the noise problem.  The pcb requires a
> > slightly different layout of putting the power on the center layers,
> > so the best bet is to look around and see if someone might have it
> > all boxed up and ready to connect.
> >
> > Were you able to find such a ready-made critter?  If so where?
>
> No I made my own circuit board, two layer. SO footprint should not be
> to hard to solder there are small prototype boards or similar on
> Farnell.
>
> http://se.farnell.com/roth-elektronik/re932-01/pcb-adaptor-smd-so-8-20
>-5mmx8mm/dp/1426169
> http://se.farnell.com/roth-elektronik/re932-03/adaptor-smd-so-14-1-27m
>m/dp/1426171
> http://se.farnell.com/roth-elektronik/re932-02/adaptor-smd-so-8w-1-27m
>m/dp/1426170
> http://se.farnell.com/roth-elektronik/re932-01st/multi-adapter-11-5x16
>mm-soic-8/dp/2292022
>
> I do not have time to check if footprint is correct.
>
Immaterial as you wouls wire to suit, but all of them are missing a place 
to put the recommended supply rail bypassing. And extra plated thru-hole 
in each runner to the terminal would be nice.

But who is Farnell on this "west side" of the pond?  Or are they even 
affiliated with anybody in the US?

Thanks Nicklas.

Cheers, Gene Heskett
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Re: [Emc-users] Modbus wiring

> > ISO7421
> 
> Now thats sweet, and a heck of a lot better thought out than the last 
> such chip I looked at a decade ago.  Needs a 4 wire cable from each 
> direction, but I don't see as that as a problem other than stealing the 
> ground and  3.3 or 5 volts to run its side of it at both ends.
> 
> That should indeed sove the noise problem.  The pcb requires a slightly 
> different layout of putting the power on the center layers, so the best 
> bet is to look around and see if someone might have it all boxed up and 
> ready to connect.
> 
> Were you able to find such a ready-made critter?  If so where?

No I made my own circuit board, two layer. SO footprint should not be to hard 
to solder there are small prototype boards or similar on Farnell.

http://se.farnell.com/roth-elektronik/re932-01/pcb-adaptor-smd-so-8-20-5mmx8mm/dp/1426169
http://se.farnell.com/roth-elektronik/re932-03/adaptor-smd-so-14-1-27mm/dp/1426171
http://se.farnell.com/roth-elektronik/re932-02/adaptor-smd-so-8w-1-27mm/dp/1426170
http://se.farnell.com/roth-elektronik/re932-01st/multi-adapter-11-5x16mm-soic-8/dp/2292022

I do not have time to check if footprint is correct.

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Re: [Emc-users] Modbus wiring

On Sunday 03 April 2016 15:07:59 Nicklas Karlsson wrote:

> ISO7421

Now thats sweet, and a heck of a lot better thought out than the last 
such chip I looked at a decade ago.  Needs a 4 wire cable from each 
direction, but I don't see as that as a problem other than stealing the 
ground and  3.3 or 5 volts to run its side of it at both ends.

That should indeed sove the noise problem.  The pcb requires a slightly 
different layout of putting the power on the center layers, so the best 
bet is to look around and see if someone might have it all boxed up and 
ready to connect.

Were you able to find such a ready-made critter?  If so where?

Thanks Nicklas.

In the FWIW dept, I looked at the serial interface data for that VFD I 
bought, and IF the interface is present, its RS232. It runs at 9600 
baud, expects a 9 byte packet control packet, and sends back a 13 byte 
status packet, with a couple tables to show what byte means what.  Not 
exactly real time, but hey, its a spindle motor.  But I don't believe 
that little postage stamp sized card is in this one.

Cheers, Gene Heskett
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Re: [Emc-users] Modbus wiring

ISO7421 is two channel bidirectional, there are more of them with different 
configurations.


On Sun, 3 Apr 2016 14:30:50 -0400
Gene Heskett  wrote:

> On Sunday 03 April 2016 14:10:04 Nicklas Karlsson wrote:
> 
> > I tried opto isolators and they did not work without errors while
> > capacitive insulation barriers did. It was a suprise and I can't tell
> > why. I think most devices including opto have a limited dv/dt
> > tolerance.
> 
> Damn, old wet ram strikes again. :(
> 
> I had forgotten there are such beasts, no doubt with limited withstand, 
> but probably enough to stop most of the noise our stuff can make.
> 
> Can you share the jedec number of the device you used?  Others here might 
> find it extremely usefull.
> 
> Thanks Nicklas.
> 
> 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] Modbus wiring

On Sunday 03 April 2016 14:10:04 Nicklas Karlsson wrote:

> I tried opto isolators and they did not work without errors while
> capacitive insulation barriers did. It was a suprise and I can't tell
> why. I think most devices including opto have a limited dv/dt
> tolerance.

Damn, old wet ram strikes again. :(

I had forgotten there are such beasts, no doubt with limited withstand, 
but probably enough to stop most of the noise our stuff can make.

Can you share the jedec number of the device you used?  Others here might 
find it extremely usefull.

Thanks Nicklas.

Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Modbus wiring

On Sunday 03 April 2016 13:36:23 Danny Miller wrote:

> Well, if you have 2 differential wires with a simple optoisolator at
> the far end, ground noise/ground loops would have no effect
> whatsoever.  You don't need a ground. There would be no place to put a
> ground.  There are no common-mode issues.  The slave device's ground
> could be +300VDC above the master's ground.
>
> However, RS485 doesn't spec that way.   The ADAM isolator box I have
> probably has optos inside, but has to make an RS485 output- which is a
> low-voltage DC differential in relation to a known ground.
>
> Danny

To me, considering the low voltages rs-485 uses, compared to the light it 
up voltages the opto's need, is a total non-starter.  The RS-485 would 
have to be amplified to a several volt differential, at the source, and 
that used to drive a laser diode, and that sent down an optical fiber to 
a diode on the other end of the fiber, and that diodes output then level 
translated back to RS485 differentials.  Such a circuit could survive 
anything but a cut fiber or a power failure.  100kv of EMP from a nearby 
lightning strike wouldn't bother it.

> On 4/3/2016 5:21 AM, Nicklas Karlsson wrote:
> > On Sat, 2 Apr 2016 11:34:25 -0400
> >
> > Gene Heskett  wrote:
> >> ...
> >> Given all that, I do not see how, in a noisy industrial
> >> environment, or even here at the Heskett's home camp, it can be
> >> error free unless an optical translator, bidirectional, is used at
> >> BOTH devices terminals.
> >
> > I am not sure about the optical translators. Why however I can't
> > tell for sure.
> >
> >> ...
> >>
> >> The question then seems to be, is who makes these rs485 to opto
> >> fiber (or even to RJ45 jacks & cat5 or cat6 cable since it doesn't
> >> have this common mode noise problem that I am aware of),
> >> bidirectional translators and at what cost.
> >
> > Ethernet which use the RJ45 connector have tranformer for
> > insulation. I have experienced communication errors over Ethernet
> > then communicating with inverter.
> >
> >
> > Nicklas Karlsson
> >
> > 
> >-- Transform Data into Opportunity.
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Re: [Emc-users] Modbus wiring

I tried opto isolators and they did not work without errors while capacitive 
insulation barriers did. It was a suprise and I can't tell why. I think most 
devices including opto have a limited dv/dt tolerance.



On Sun, 3 Apr 2016 12:36:23 -0500
Danny Miller  wrote:

> Well, if you have 2 differential wires with a simple optoisolator at the 
> far end, ground noise/ground loops would have no effect whatsoever.  You 
> don't need a ground. There would be no place to put a ground.  There are 
> no common-mode issues.  The slave device's ground could be +300VDC above 
> the master's ground.
> 
> However, RS485 doesn't spec that way.   The ADAM isolator box I have 
> probably has optos inside, but has to make an RS485 output- which is a 
> low-voltage DC differential in relation to a known ground.
> 
> Danny
> 
> On 4/3/2016 5:21 AM, Nicklas Karlsson wrote:
> > On Sat, 2 Apr 2016 11:34:25 -0400
> > Gene Heskett  wrote:
> >> ...
> >> Given all that, I do not see how, in a noisy industrial environment, or
> >> even here at the Heskett's home camp, it can be error free unless an
> >> optical translator, bidirectional, is used at BOTH devices terminals.
> > I am not sure about the optical translators. Why however I can't tell for 
> > sure.
> >
> >> ...
> >>
> >> The question then seems to be, is who makes these rs485 to opto fiber (or
> >> even to RJ45 jacks & cat5 or cat6 cable since it doesn't have this
> >> common mode noise problem that I am aware of), bidirectional translators
> >> and at what cost.
> > Ethernet which use the RJ45 connector have tranformer for insulation. I 
> > have experienced communication errors over Ethernet then communicating with 
> > inverter.
> >
> >
> > Nicklas Karlsson
> >
> > --
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> >
> 
> 
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Re: [Emc-users] Modbus wiring

On Sunday 03 April 2016 09:35:04 Nicklas Karlsson wrote:

[huge snip]

> You could also read if there is something in the manual about a
> shielded cable and how it should be connected.
>
>
> Nicklas Karlsson

Such information is not mentioned in my Chinglish manual.  And thats 
troublesome too IMO.

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Re: [Emc-users] Modbus wiring

2016-04-03 Thread Danny Miller

Well, if you have 2 differential wires with a simple optoisolator at the 
far end, ground noise/ground loops would have no effect whatsoever.  You 
don't need a ground. There would be no place to put a ground.  There are 
no common-mode issues.  The slave device's ground could be +300VDC above 
the master's ground.

However, RS485 doesn't spec that way.   The ADAM isolator box I have 
probably has optos inside, but has to make an RS485 output- which is a 
low-voltage DC differential in relation to a known ground.

Danny

On 4/3/2016 5:21 AM, Nicklas Karlsson wrote:
> On Sat, 2 Apr 2016 11:34:25 -0400
> Gene Heskett  wrote:
>> ...
>> Given all that, I do not see how, in a noisy industrial environment, or
>> even here at the Heskett's home camp, it can be error free unless an
>> optical translator, bidirectional, is used at BOTH devices terminals.
> I am not sure about the optical translators. Why however I can't tell for 
> sure.
>
>> ...
>>
>> The question then seems to be, is who makes these rs485 to opto fiber (or
>> even to RJ45 jacks & cat5 or cat6 cable since it doesn't have this
>> common mode noise problem that I am aware of), bidirectional translators
>> and at what cost.
> Ethernet which use the RJ45 connector have tranformer for insulation. I have 
> experienced communication errors over Ethernet then communicating with 
> inverter.
>
>
> Nicklas Karlsson
>
> --
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>


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Re: [Emc-users] Modbus wiring

> > Gene Heskett  wrote:
> > > On Saturday 02 April 2016 07:04:14 Nicklas Karlsson wrote:
> > > > > I had SERIOUS problems with my X200 VFD and RS485 bus- I
> > > > > "mostly" fixed it.
> > > > >
> > > > > Here's the thing- yes, RS485 is differential, but the VFD is
> > > > > probably NOT opto-isolated input.  Differential conveys strong
> > > > > noise immunity- but ONLY when both A and B wires' voltages are
> > > > > within the input range of the VFD's bus driver, which might be
> > > > > -0.5v to 7v relative to the ground on the VFD driver chip.
> > > > > Outside that range, it will NOT function.
> > > > >
> > > > > The X200 confuses me greatly.  Yes is has an A and B RS485
> > > > > terminals, but no ground on the RJ45 jack.  If you don't have a
> > > > > ground to connect to, this problem can easily come up, and DID. 
> > > > > I had to take apart the VFD to measure this- like >20v of noise
> > > > > between the PC ground and the VFD driver.  That will NOT work,
> > > > > and didn't.
> > > >
> > > > You just hit the major problem with switched power electronics,
> > > > common mode voltages. A common mode choke will increase common
> > > > mode impedance. Increased impedance will not by itself decrease
> > > > voltage but if some current could be conducted away the higher
> > > > impedance will however lower voltage. One problem is even though
> > > > ground resistance is close to zero impedance is not. I remember I
> > > > have read a value of 50µH as maximum power grid inductance but are
> > > > not totally sure this is correct and particular not for all
> > > > frequencies.
> > > >
> > > > Common mode voltage source is capacitance between switch power
> > > > electronics conductor with a "square" voltage and ground. It is
> > > > probably correct to think about it as a capacitor connected to
> > > > ground which is switched between the two rectified voltage
> > > > potentials.
> > > >
> > > > There is capacitor between: "square" voltage between inverter
> > > > transistors and cooling fin. In electric motor between phases and
> > > > ground.
> > > >
> > > >
> > > > Different insulation barrier technologies are more or less
> > > > tolerant to common mode voltage. I think capcitive insulation
> > > > barriers like these used in Texas Instruments ISO7421 are tolerant
> > > > against common mode voltage.
> > >
> > > ...
> > > Given all that, I do not see how, in a noisy industrial environment,
> > > or even here at the Heskett's home camp, it can be error free unless
> > > an optical translator, bidirectional, is used at BOTH devices
> > > terminals.
> >
> > I am not sure about the optical translators. Why however I can't tell
> > for sure.
> >
> > > ...
> > >
> > > The question then seems to be, is who makes these rs485 to opto
> > > fiber (or even to RJ45 jacks & cat5 or cat6 cable since it doesn't
> > > have this common mode noise problem that I am aware of),
> > > bidirectional translators and at what cost.
> >
> > Ethernet which use the RJ45 connector have tranformer for insulation.
> > I have experienced communication errors over Ethernet then
> > communicating with inverter.
> >
> >
> > Nicklas Karlsson
> 
> Well, in any event, it seems to me like it is time to get out the scope 
> and see if the interfering noise can be found.  If the noise is in the 
> VFD, I'd certainly contact the vendor for a solution.  Failing that, I 
> believe I'd get another VFD from a diferent source, and if it works, 
> then some bad publicity about the first one and lack of support should 
> be related here on this list.  This is not the only list of course, but 
> bad publicity  should cause a down tick in sales.  And that does send a 
> message.  You bought the product to USE it,  and if its not usable, warn 
> the rest of us.

You could also read if there is something in the manual about a shielded cable 
and how it should be connected.


Nicklas Karlsson

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Re: [Emc-users] Modbus wiring

On Sunday 03 April 2016 06:21:38 Nicklas Karlsson wrote:

> On Sat, 2 Apr 2016 11:34:25 -0400
>
> Gene Heskett  wrote:
> > On Saturday 02 April 2016 07:04:14 Nicklas Karlsson wrote:
> > > > I had SERIOUS problems with my X200 VFD and RS485 bus- I
> > > > "mostly" fixed it.
> > > >
> > > > Here's the thing- yes, RS485 is differential, but the VFD is
> > > > probably NOT opto-isolated input.  Differential conveys strong
> > > > noise immunity- but ONLY when both A and B wires' voltages are
> > > > within the input range of the VFD's bus driver, which might be
> > > > -0.5v to 7v relative to the ground on the VFD driver chip.
> > > > Outside that range, it will NOT function.
> > > >
> > > > The X200 confuses me greatly.  Yes is has an A and B RS485
> > > > terminals, but no ground on the RJ45 jack.  If you don't have a
> > > > ground to connect to, this problem can easily come up, and DID. 
> > > > I had to take apart the VFD to measure this- like >20v of noise
> > > > between the PC ground and the VFD driver.  That will NOT work,
> > > > and didn't.
> > >
> > > You just hit the major problem with switched power electronics,
> > > common mode voltages. A common mode choke will increase common
> > > mode impedance. Increased impedance will not by itself decrease
> > > voltage but if some current could be conducted away the higher
> > > impedance will however lower voltage. One problem is even though
> > > ground resistance is close to zero impedance is not. I remember I
> > > have read a value of 50µH as maximum power grid inductance but are
> > > not totally sure this is correct and particular not for all
> > > frequencies.
> > >
> > > Common mode voltage source is capacitance between switch power
> > > electronics conductor with a "square" voltage and ground. It is
> > > probably correct to think about it as a capacitor connected to
> > > ground which is switched between the two rectified voltage
> > > potentials.
> > >
> > > There is capacitor between: "square" voltage between inverter
> > > transistors and cooling fin. In electric motor between phases and
> > > ground.
> > >
> > >
> > > Different insulation barrier technologies are more or less
> > > tolerant to common mode voltage. I think capcitive insulation
> > > barriers like these used in Texas Instruments ISO7421 are tolerant
> > > against common mode voltage.
> >
> > ...
> > Given all that, I do not see how, in a noisy industrial environment,
> > or even here at the Heskett's home camp, it can be error free unless
> > an optical translator, bidirectional, is used at BOTH devices
> > terminals.
>
> I am not sure about the optical translators. Why however I can't tell
> for sure.
>
> > ...
> >
> > The question then seems to be, is who makes these rs485 to opto
> > fiber (or even to RJ45 jacks & cat5 or cat6 cable since it doesn't
> > have this common mode noise problem that I am aware of),
> > bidirectional translators and at what cost.
>
> Ethernet which use the RJ45 connector have tranformer for insulation.
> I have experienced communication errors over Ethernet then
> communicating with inverter.
>
>
> Nicklas Karlsson

Well, in any event, it seems to me like it is time to get out the scope 
and see if the interfering noise can be found.  If the noise is in the 
VFD, I'd certainly contact the vendor for a solution.  Failing that, I 
believe I'd get another VFD from a diferent source, and if it works, 
then some bad publicity about the first one and lack of support should 
be related here on this list.  This is not the only list of course, but 
bad publicity  should cause a down tick in sales.  And that does send a 
message.  You bought the product to USE it,  and if its not usable, warn 
the rest of us.

On the mix-n-match 1.5HP I just bought, there is a common point, but its 
labeled as the ccw end of a manual speed control potentiometer.  And I 
have been assured by the vendor that using that for a logic ground, I 
can feed the PWM straight into the arm of the pot as its well filtered 
internally for just that use.  It has 0-5 volt input range, and a 0-10 
volt range as separate terminals.

If that terminal exists on yours, then I would connect that terminal to 
the logic ground of your RS-485 driver circuitry.  That should solve any 
common mode out of range errors.  That's generally going to be the 
reason when the noise has exceeded the active range of the loads input 
comparators.  That range would be from say .5 volts above the logic 
ground, to .5 volts below the + supply rail of the receiver.  I have 
seen some chips claim to be able to go all the way to the rails, but I 
would not put a 5 nines dependable rating on such a circuit.

The reason for that is the substrate diodes in the receiver IC, will have 
a measurable turnoff recovery time, and could output the wrong logic 
level during that time. That would generate edge triggered noise that 
could easily upset the receivers intention of sampling in the center of

Re: [Emc-users] Modbus wiring

On Sat, 2 Apr 2016 11:34:25 -0400
Gene Heskett  wrote:

> On Saturday 02 April 2016 07:04:14 Nicklas Karlsson wrote:
> 
> > > I had SERIOUS problems with my X200 VFD and RS485 bus- I "mostly"
> > > fixed it.
> > >
> > > Here's the thing- yes, RS485 is differential, but the VFD is
> > > probably NOT opto-isolated input.  Differential conveys strong noise
> > > immunity- but ONLY when both A and B wires' voltages are within the
> > > input range of the VFD's bus driver, which might be -0.5v to 7v
> > > relative to the ground on the VFD driver chip. Outside that range,
> > > it will NOT function.
> > >
> > > The X200 confuses me greatly.  Yes is has an A and B RS485
> > > terminals, but no ground on the RJ45 jack.  If you don't have a
> > > ground to connect to, this problem can easily come up, and DID.  I
> > > had to take apart the VFD to measure this- like >20v of noise
> > > between the PC ground and the VFD driver.  That will NOT work, and
> > > didn't.
> >
> > You just hit the major problem with switched power electronics, common
> > mode voltages. A common mode choke will increase common mode
> > impedance. Increased impedance will not by itself decrease voltage but
> > if some current could be conducted away the higher impedance will
> > however lower voltage. One problem is even though ground resistance is
> > close to zero impedance is not. I remember I have read a value of 50µH
> > as maximum power grid inductance but are not totally sure this is
> > correct and particular not for all frequencies.
> >
> > Common mode voltage source is capacitance between switch power
> > electronics conductor with a "square" voltage and ground. It is
> > probably correct to think about it as a capacitor connected to ground
> > which is switched between the two rectified voltage potentials.
> >
> > There is capacitor between: "square" voltage between inverter
> > transistors and cooling fin. In electric motor between phases and
> > ground.
> >
> >
> > Different insulation barrier technologies are more or less tolerant to
> > common mode voltage. I think capcitive insulation barriers like these
> > used in Texas Instruments ISO7421 are tolerant against common mode
> > voltage.
> ...
> Given all that, I do not see how, in a noisy industrial environment, or 
> even here at the Heskett's home camp, it can be error free unless an 
> optical translator, bidirectional, is used at BOTH devices terminals. 

I am not sure about the optical translators. Why however I can't tell for sure.

> ...
> 
> The question then seems to be, is who makes these rs485 to opto fiber (or 
> even to RJ45 jacks & cat5 or cat6 cable since it doesn't have this 
> common mode noise problem that I am aware of), bidirectional translators 
> and at what cost.

Ethernet which use the RJ45 connector have tranformer for insulation. I have 
experienced communication errors over Ethernet then communicating with inverter.


Nicklas Karlsson

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Re: [Emc-users] Modbus wiring

2016-04-02 Thread Gene Heskett

On Saturday 02 April 2016 07:04:14 Nicklas Karlsson wrote:

> > I had SERIOUS problems with my X200 VFD and RS485 bus- I "mostly"
> > fixed it.
> >
> > Here's the thing- yes, RS485 is differential, but the VFD is
> > probably NOT opto-isolated input.  Differential conveys strong noise
> > immunity- but ONLY when both A and B wires' voltages are within the
> > input range of the VFD's bus driver, which might be -0.5v to 7v
> > relative to the ground on the VFD driver chip. Outside that range,
> > it will NOT function.
> >
> > The X200 confuses me greatly.  Yes is has an A and B RS485
> > terminals, but no ground on the RJ45 jack.  If you don't have a
> > ground to connect to, this problem can easily come up, and DID.  I
> > had to take apart the VFD to measure this- like >20v of noise
> > between the PC ground and the VFD driver.  That will NOT work, and
> > didn't.
>
> You just hit the major problem with switched power electronics, common
> mode voltages. A common mode choke will increase common mode
> impedance. Increased impedance will not by itself decrease voltage but
> if some current could be conducted away the higher impedance will
> however lower voltage. One problem is even though ground resistance is
> close to zero impedance is not. I remember I have read a value of 50µH
> as maximum power grid inductance but are not totally sure this is
> correct and particular not for all frequencies.
>
> Common mode voltage source is capacitance between switch power
> electronics conductor with a "square" voltage and ground. It is
> probably correct to think about it as a capacitor connected to ground
> which is switched between the two rectified voltage potentials.
>
> There is capacitor between: "square" voltage between inverter
> transistors and cooling fin. In electric motor between phases and
> ground.
>
>
> Different insulation barrier technologies are more or less tolerant to
> common mode voltage. I think capcitive insulation barriers like these
> used in Texas Instruments ISO7421 are tolerant against common mode
> voltage.

Having just trolled thru wikipedia's entries for RS-485, ModBus and 
ProfiBus, I have reluctantly come to the conclusion that so much is 
unspecified, that you can call most anything RS-485 and get away with 
it.

Hell of a way to run a train.

I would start, with everything powered down and unplugged, by checking to 
see, with an ohmmeter, if the 120 ohm termination is there, which it 
should be ON BOTH ENDS as its a bidirectional protocol in 99% of the use 
cases I can think of.  This is wire to wire at the terminals on both 
devices. Then I would similarly measure from each wire to common looking 
for a resistance lower than the 680 shown, could be as low as 390 if the 
PSU electrolytic's in both devices aren't displaying any dielectric 
absorbtion, where even though discharged, they act somewhat like a low 
voltage battery, its quite common.  To counter some of that, reverse the 
test leads and use the median of the two measurements.

If that termination isn't found, figure out a way to add it.  It should 
have been a hard and fast part of the specs, but isn't according to what 
I read on wikipedia.  And neither is a common connection.

That may have been a safety exclusion they didn't state clearly. But some 
of the specs show it being implemented at the outputs of a 3.3 volt 
capable card.  That alone reduces the range of the common mode input 
voltage where error free operation can be obtained between two devices 
whose only common connection might be the house static ground, here in 
the US , the third round pin on the plug.  And that can carry lots of HF 
noise as its generally a star config, common only at the building 
electrical entrance.

Given all that, I do not see how, in a noisy industrial environment, or 
even here at the Heskett's home camp, it can be error free unless an 
optical translator, bidirectional, is used at BOTH devices terminals. 
That, if the devices were carefull might be done on a single fiber by 
cross-polarizing the light beams which in typical useage can give 30 db 
of isolation between tx and rx.  That of course can be degraded by 
sharper turns in the fibers path but over the distances used in the shop 
environment, could be largely tuned out by allowing one of the devices 
to be rotated axially on the fibers axis.

The question then seems to be, is who makes these rs485 to opto fiber (or 
even to RJ45 jacks & cat5 or cat6 cable since it doesn't have this 
common mode noise problem that I am aware of), bidirectional translators 
and at what cost.

When I say "that I am aware of" I have a piece of cat5 running between an 
eyehook at the end of my back porch, up across the yard high enough its 
overhead, 30 feet or so to an eyehook at the peak of my "shop" building, 
from there is smashed by the closing door, hooked to a 4 port hub in 
there, and thence to 2, sometimes 3 machines via cat5 from the hub to 
them.  And its been there since about

Re: [Emc-users] Modbus wiring

2016-04-02 Thread Nicklas Karlsson

> I had SERIOUS problems with my X200 VFD and RS485 bus- I "mostly" fixed it.
> 
> Here's the thing- yes, RS485 is differential, but the VFD is probably 
> NOT opto-isolated input.  Differential conveys strong noise immunity- 
> but ONLY when both A and B wires' voltages are within the input range of 
> the VFD's bus driver, which might be -0.5v to 7v relative to the ground 
> on the VFD driver chip. Outside that range, it will NOT function.
> 
> The X200 confuses me greatly.  Yes is has an A and B RS485 terminals, 
> but no ground on the RJ45 jack.  If you don't have a ground to connect 
> to, this problem can easily come up, and DID.  I had to take apart the 
> VFD to measure this- like >20v of noise between the PC ground and the 
> VFD driver.  That will NOT work, and didn't.

You just hit the major problem with switched power electronics, common mode 
voltages. A common mode choke will increase common mode impedance. Increased 
impedance will not by itself decrease voltage but if some current could be 
conducted away the higher impedance will however lower voltage. One problem is 
even though ground resistance is close to zero impedance is not. I remember I 
have read a value of 50µH as maximum power grid inductance but are not totally 
sure this is correct and particular not for all frequencies.

Common mode voltage source is capacitance between switch power electronics 
conductor with a "square" voltage and ground. It is probably correct to think 
about it as a capacitor connected to ground which is switched between the two 
rectified voltage potentials.

There is capacitor between: "square" voltage between inverter transistors and 
cooling fin. In electric motor between phases and ground.


Different insulation barrier technologies are more or less tolerant to common 
mode voltage. I think capcitive insulation barriers like these used in Texas 
Instruments ISO7421 are tolerant against common mode voltage.


I would still be happy to show my trick to turn gold to lead if someone is 
interested?


Nicklas Karlsson

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Re: [Emc-users] Modbus wiring

2016-04-01 Thread Danny Miller

I had SERIOUS problems with my X200 VFD and RS485 bus- I "mostly" fixed it.

Here's the thing- yes, RS485 is differential, but the VFD is probably 
NOT opto-isolated input.  Differential conveys strong noise immunity- 
but ONLY when both A and B wires' voltages are within the input range of 
the VFD's bus driver, which might be -0.5v to 7v relative to the ground 
on the VFD driver chip. Outside that range, it will NOT function.

The X200 confuses me greatly.  Yes is has an A and B RS485 terminals, 
but no ground on the RJ45 jack.  If you don't have a ground to connect 
to, this problem can easily come up, and DID.  I had to take apart the 
VFD to measure this- like >20v of noise between the PC ground and the 
VFD driver.  That will NOT work, and didn't.

You might think "there's that 'L' terminal in front for 'Logic Ground', 
I'll tie the RS485 ground together there".  But I measured, it's not 
tied to the RS485 driver's ground- which is confusing and weird but 
that's what it is.  Clearly Hitachi did NOT intend for it to be ground, 
since it's not on the RJ45 jack. It'd be awkward to have a removable 
RJ45 and a nonpluggable ground.

I ended up using an ADAM isolated RS232-RS485 bridge (needed to get 
RS232 to RS485 anyhow).  This is still questionable because I STILL only 
floated the RS485 ground- but that's better than having it referenced to 
something guaranteed to be incompatible with the X200's ground.  
Snooping the bus driver, the Modbus does get a bad transaction like 10% 
of the time but that's good enough.

I honestly don't know how Hitachi intended for that X200 to work. In the 
WJ200 manual, they show "L" IS supposed to be the ground for RS485 comm, 
though.  I went through the manual and can't find the pinout for the 
RJ45 jack, I don't know if they included a ground or not.  I guess 
that's what they intended for the X200 too, to use the "L" as gnd?

But anyhow-

The X200 and WJ200 at least have optional internal termination 
resistors.  But you're only supposed to build a modbus in a line and 
only the end device can have a termination resistor.

"Quality" of wire will NOT matter much especially in short lengths like 
<3m or whatever.

Danny

On 3/30/2016 11:13 AM, andy pugh wrote:
> On 9 February 2016 at 11:23, andy pugh  wrote:
>> This is where things get iffy. Imagine that I have the 2-terminal
>> dongle plugged into a laptop. What do I use for a gnd? Stuff a wire
>> down the side of the USB connector? trap the wire in the hinge? :-)
> In the end, I fitted a different VFD which has a pre-written HAL driver.
> It also only has two connections for RS485, so is less confusing.
> I found a way to connect the dongle to the motherboard header:
> https://forum.linuxcnc.org/forum/18-computer/30675-on-motherboard-modbus-rs485-connection
> They are so cheap that I was prepared to go through a couple
> experimenting, but it works fine.
>

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Re: [Emc-users] Modbus wiring

On Friday 01 April 2016 17:17:16 John Thornton wrote:

> You're going to turn copper to steel?
>
Puzzled me too John, until I remembered the date.  Today I don't believe 
a thing I read, and only about 5% of what I see.

> On 4/1/2016 3:57 PM, Nicklas Karlsson wrote:
> >> On 1 April 2016 at 20:07, Dave Cole  wrote:
> >>> Profibus is basically an RS485 network as well.I have no idea
> >>> why they used a purple jacket color.
> >>
> >> There is an awful lot of purple wiring on the London Underground.
> >> Perhaps that is data cable.
> >
> > What do you plan to do with it? Steel it?
> >
> > 
> >-- Transform Data into Opportunity.
> > Accelerate data analysis in your applications with
> > Intel Data Analytics Acceleration Library.
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>
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Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
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Re: [Emc-users] Modbus wiring

I can turn gold to lead, do you want see. It should have been that kind of 
steal.


> You're going to turn copper to steel?
> 
> On 4/1/2016 3:57 PM, Nicklas Karlsson wrote:
> >> On 1 April 2016 at 20:07, Dave Cole  wrote:
> >>> Profibus is basically an RS485 network as well.I have no idea why
> >>> they used a purple jacket color.
> >> There is an awful lot of purple wiring on the London Underground.
> >> Perhaps that is data cable.
> > What do you plan to do with it? Steel it?
> >
> > --
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> > Accelerate data analysis in your applications with
> > Intel Data Analytics Acceleration Library.
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> > https://lists.sourceforge.net/lists/listinfo/emc-users
> 
> 
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Re: [Emc-users] Modbus wiring

On 4/1/2016 1:48 PM, andy pugh wrote:
> On 1 April 2016 at 20:07, Dave Cole  wrote:
>> Profibus is basically an RS485 network as well.I have no idea why
>> they used a purple jacket color.
> There is an awful lot of purple wiring on the London Underground.
> Perhaps that is data cable.

Siemens makes subway cars and rail control systems.If they did the 
control system, then it is likely Profibus cable.  Its frequently used 
for I/O systems.

Dave

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Re: [Emc-users] Modbus wiring

2016-04-01 Thread John Thornton

You're going to turn copper to steel?

On 4/1/2016 3:57 PM, Nicklas Karlsson wrote:
>> On 1 April 2016 at 20:07, Dave Cole  wrote:
>>> Profibus is basically an RS485 network as well.I have no idea why
>>> they used a purple jacket color.
>> There is an awful lot of purple wiring on the London Underground.
>> Perhaps that is data cable.
> What do you plan to do with it? Steel it?
>
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Re: [Emc-users] Modbus wiring

> On 1 April 2016 at 20:07, Dave Cole  wrote:
> > Profibus is basically an RS485 network as well.I have no idea why
> > they used a purple jacket color.
> 
> There is an awful lot of purple wiring on the London Underground.
> Perhaps that is data cable.

What do you plan to do with it? Steel it?

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Re: [Emc-users] Modbus wiring

On Friday 01 April 2016 13:58:55 Stephen Dubovsky wrote:

> You can not include the termination or pull up/down resistors on a
> RS422/485 network in the drivers (unless they can by disabled.)  You
> don't know where (or how many) are located on the bus.  They are
> multi-drop networks after all.  Only terminate the two far ends.
>
Thank you Stephen, I hadn't remembered that as I only had one instance of 
it, point to point at the tv station, and it Just Worked(TM).

Can I blame it on aged wet ram?  You are of course correct.
>
> On Fri, Apr 1, 2016 at 1:37 PM, Nicklas Karlsson <
>
> nicklas.karlsso...@gmail.com> wrote:
> > > > > Twisted pair is a transmission line and subject to all the
> > > > > vagaries of load matching and such.
> > > > >
> > > > > That cables impedance is not listed there,
> > > >
> > > > Yes it is. 120 Ohms.
> > >
> > > Resistance is NOT impedance, Andy.  And I first read that as 1200
> > > because my screen is high res and the ohm sign looks like another
> > > 0 at first glance, I mentaly threw that whole line out as being
> > > technically impractical, written by someone who obviously did not
> > > understand anything about transmission line theory.  My bad for
> > > the miss read of 120 ohms as 1200 ohms, but still the use of the
> > > word resistance renders it null and void in my technical mind.  If
> > > they meant impedance, they should have written impedance. If the
> > > loads J dactor is 0, then they would directly correspond, but that
> > > J=0 generally would be quite rare in the real world.
> > >
> > > However, my comments about the load termination, in this case with
> > > a 120 ohm resistor from wire to wire at the load end are still
> > > valid.
> >
> > https://www.expertdaq.com/static/img/info/RS485-termination-120-ohm.
> >gif
> >
> > I think the extra bias network to power rails is necessary to get
> > correct level in between data is sent.
> >
> > > Properly done, thats taken care of in the rs485 interface in the
> > > device, but you never know when some bean counter between the
> > > engineer and the production line will delete that seemingly
> > > useless part as a cost saver.
> >
> > They save beans in the short but have to spend more of them later.
> > By investing the beans in rather good fast growing soil they figured
> > out they could return more of them later but still have some left
> > for them self.
> >
> >
> > 
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Re: [Emc-users] Modbus wiring

Well that is true.   It does tend to stand out from the generic gray 
control cabling.

Dave

On 4/1/2016 1:26 PM, Peter Blodow wrote:
> ... because this will be different from all other kinds of cables.
> Imagine large facilities, dozens of buildings, with thousands of devices
> being controlled by a central control room, wired by random cable
> colours. These are being mixed with current supply, LAN, telephone and
> all other cables together on a cable way... I was one of these customers
> who urged the companies and the DIN authorities to use easily
> identifiable cables for building control.
>
> Peter Blodow
>
>
>
> Am 01.04.2016 21:07, schrieb Dave Cole:
>> Profibus is basically an RS485 network as well. I have no idea why
>> they used a purple jacket color. Dave
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Re: [Emc-users] Modbus wiring

On 1 April 2016 at 20:07, Dave Cole  wrote:
> Profibus is basically an RS485 network as well.I have no idea why
> they used a purple jacket color.

There is an awful lot of purple wiring on the London Underground.
Perhaps that is data cable.

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Re: [Emc-users] Modbus wiring

2016-04-01 Thread Peter Blodow

... because this will be different from all other kinds of cables. 
Imagine large facilities, dozens of buildings, with thousands of devices 
being controlled by a central control room, wired by random cable 
colours. These are being mixed with current supply, LAN, telephone and 
all other cables together on a cable way... I was one of these customers 
who urged the companies and the DIN authorities to use easily 
identifiable cables for building control.

Peter Blodow



Am 01.04.2016 21:07, schrieb Dave Cole:
> Profibus is basically an RS485 network as well. I have no idea why 
> they used a purple jacket color. Dave 

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Re: [Emc-users] Modbus wiring

On 4/1/2016 11:55 AM, andy pugh wrote:
> On 1 April 2016 at 18:33, Dave Cole  wrote:
>> Unless you are running at 60+ Kbaud and up and long distances you likely
>> won't need anything but twisted pair cabling.
> It was mainly the purple thing.
Ha ha...

Well,  I must like purple also.I have the remains of a 1000 ft spool 
of some purple Siemens Profibus cable that looks almost identical to 
that cable.
Profibus is basically an RS485 network as well.I have no idea why 
they used a purple jacket color.

Dave
>

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Re: [Emc-users] Modbus wiring

Yes termination with pull up/down in both ends.


On Fri, 1 Apr 2016 13:58:55 -0400
Stephen Dubovsky  wrote:

> You can not include the termination or pull up/down resistors on a
> RS422/485 network in the drivers (unless they can by disabled.)  You don't
> know where (or how many) are located on the bus.  They are multi-drop
> networks after all.  Only terminate the two far ends.
> 
> 
> On Fri, Apr 1, 2016 at 1:37 PM, Nicklas Karlsson <
> nicklas.karlsso...@gmail.com> wrote:
> 
> > > > > Twisted pair is a transmission line and subject to all the vagaries
> > > > > of load matching and such.
> > > > >
> > > > > That cables impedance is not listed there,
> > > >
> > > > Yes it is. 120 Ohms.
> > >
> > > Resistance is NOT impedance, Andy.  And I first read that as 1200 because
> > > my screen is high res and the ohm sign looks like another 0 at first
> > > glance, I mentaly threw that whole line out as being technically
> > > impractical, written by someone who obviously did not understand
> > > anything about transmission line theory.  My bad for the miss read of
> > > 120 ohms as 1200 ohms, but still the use of the word resistance renders
> > > it null and void in my technical mind.  If they meant impedance, they
> > > should have written impedance. If the loads J dactor is 0, then they
> > > would directly correspond, but that J=0 generally would be quite rare in
> > > the real world.
> > >
> > > However, my comments about the load termination, in this case with a 120
> > > ohm resistor from wire to wire at the load end are still valid.
> >
> > https://www.expertdaq.com/static/img/info/RS485-termination-120-ohm.gif
> >
> > I think the extra bias network to power rails is necessary to get correct
> > level in between data is sent.
> >
> > > Properly done, thats taken care of in the rs485 interface in the device,
> > > but you never know when some bean counter between the engineer and the
> > > production line will delete that seemingly useless part as a cost saver.
> >
> > They save beans in the short but have to spend more of them later. By
> > investing the beans in rather good fast growing soil they figured out they
> > could return more of them later but still have some left for them self.
> >
> >
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Re: [Emc-users] Modbus wiring

2016-04-01 Thread Stephen Dubovsky

You can not include the termination or pull up/down resistors on a
RS422/485 network in the drivers (unless they can by disabled.)  You don't
know where (or how many) are located on the bus.  They are multi-drop
networks after all.  Only terminate the two far ends.


On Fri, Apr 1, 2016 at 1:37 PM, Nicklas Karlsson <
nicklas.karlsso...@gmail.com> wrote:

> > > > Twisted pair is a transmission line and subject to all the vagaries
> > > > of load matching and such.
> > > >
> > > > That cables impedance is not listed there,
> > >
> > > Yes it is. 120 Ohms.
> >
> > Resistance is NOT impedance, Andy.  And I first read that as 1200 because
> > my screen is high res and the ohm sign looks like another 0 at first
> > glance, I mentaly threw that whole line out as being technically
> > impractical, written by someone who obviously did not understand
> > anything about transmission line theory.  My bad for the miss read of
> > 120 ohms as 1200 ohms, but still the use of the word resistance renders
> > it null and void in my technical mind.  If they meant impedance, they
> > should have written impedance. If the loads J dactor is 0, then they
> > would directly correspond, but that J=0 generally would be quite rare in
> > the real world.
> >
> > However, my comments about the load termination, in this case with a 120
> > ohm resistor from wire to wire at the load end are still valid.
>
> https://www.expertdaq.com/static/img/info/RS485-termination-120-ohm.gif
>
> I think the extra bias network to power rails is necessary to get correct
> level in between data is sent.
>
> > Properly done, thats taken care of in the rs485 interface in the device,
> > but you never know when some bean counter between the engineer and the
> > production line will delete that seemingly useless part as a cost saver.
>
> They save beans in the short but have to spend more of them later. By
> investing the beans in rather good fast growing soil they figured out they
> could return more of them later but still have some left for them self.
>
>
> --
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Re: [Emc-users] Modbus wiring

> > > Twisted pair is a transmission line and subject to all the vagaries
> > > of load matching and such.
> > >
> > > That cables impedance is not listed there,
> >
> > Yes it is. 120 Ohms.
> 
> Resistance is NOT impedance, Andy.  And I first read that as 1200 because 
> my screen is high res and the ohm sign looks like another 0 at first 
> glance, I mentaly threw that whole line out as being technically 
> impractical, written by someone who obviously did not understand 
> anything about transmission line theory.  My bad for the miss read of 
> 120 ohms as 1200 ohms, but still the use of the word resistance renders 
> it null and void in my technical mind.  If they meant impedance, they 
> should have written impedance. If the loads J dactor is 0, then they 
> would directly correspond, but that J=0 generally would be quite rare in 
> the real world.
> 
> However, my comments about the load termination, in this case with a 120 
> ohm resistor from wire to wire at the load end are still valid.

https://www.expertdaq.com/static/img/info/RS485-termination-120-ohm.gif

I think the extra bias network to power rails is necessary to get correct level 
in between data is sent.

> Properly done, thats taken care of in the rs485 interface in the device, 
> but you never know when some bean counter between the engineer and the 
> production line will delete that seemingly useless part as a cost saver.

They save beans in the short but have to spend more of them later. By investing 
the beans in rather good fast growing soil they figured out they could return 
more of them later but still have some left for them self.

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Re: [Emc-users] Modbus wiring

On 1 April 2016 at 16:58, John Dammeyer  wrote:
> Which cable is the Van Damme?
> Can you post an ebay # or link?

http://www.ebay.co.uk/itm/141838984494

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Re: [Emc-users] Modbus wiring

On Friday 01 April 2016 11:33:18 andy pugh wrote:

> On 1 April 2016 at 16:22, Gene Heskett  wrote:
> >> http://www.rapidonline.com/cables-connectors/belden-9841-data-cable
> >>-for-rs-485-51-6887
> >
> > Twisted pair is a transmission line and subject to all the vagaries
> > of load matching and such.
> >
> > That cables impedance is not listed there,
>
> Yes it is. 120 Ohms.

Resistance is NOT impedance, Andy.  And I first read that as 1200 because 
my screen is high res and the ohm sign looks like another 0 at first 
glance, I mentaly threw that whole line out as being technically 
impractical, written by someone who obviously did not understand 
anything about transmission line theory.  My bad for the miss read of 
120 ohms as 1200 ohms, but still the use of the word resistance renders 
it null and void in my technical mind.  If they meant impedance, they 
should have written impedance. If the loads J dactor is 0, then they 
would directly correspond, but that J=0 generally would be quite rare in 
the real world.

However, my comments about the load termination, in this case with a 120 
ohm resistor from wire to wire at the load end are still valid.  
Properly done, thats taken care of in the rs485 interface in the device, 
but you never know when some bean counter between the engineer and the 
production line will delete that seemingly useless part as a cost saver.

I learned 25 years ago to never, ever, discount that possibility when 
something wasn't working right.  The places where a well designed 
product was made into a wholesale failure make up quite a few of my "war 
stories".

> It is also specifically described as RS-485 cable.
>
> But I also noticed that Van Damme list their DMX cable as suitable for
> RS-485 and that that is available from eBay at fairly low cost, so
> ordered some in on a "just in case" basis.
> It is also a pretty purple colour.

Chuckle.  The "oh look, a pony" thing. ;)  The electrons are color blind.
Which is a good thing IMO, since if you see that color 5 years later, you 
should recall that the cable is an RS485 circuit, and thats a Good 
Thing(TM).

Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Modbus wiring

On 1 April 2016 at 18:33, Dave Cole  wrote:
> Unless you are running at 60+ Kbaud and up and long distances you likely
> won't need anything but twisted pair cabling.

It was mainly the purple thing.

-- 
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Re: [Emc-users] Modbus wiring

On 4/1/2016 10:33 AM, andy pugh wrote:
> On 1 April 2016 at 16:22, Gene Heskett  wrote:
>>> http://www.rapidonline.com/cables-connectors/belden-9841-data-cable-for-rs-485-51-6887
>> Twisted pair is a transmission line and subject to all the vagaries of
>> load matching and such.
>>
>> That cables impedance is not listed there,
> Yes it is. 120 Ohms.
> It is also specifically described as RS-485 cable.
>
> But I also noticed that Van Damme list their DMX cable as suitable for
> RS-485 and that that is available from eBay at fairly low cost, so
> ordered some in on a "just in case" basis.
> It is also a pretty purple colour.

Unless you are running at 60+ Kbaud and up and long distances you likely 
won't need anything but twisted pair cabling.

Ethernet cable will work fine.

Dave



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Re: [Emc-users] Modbus wiring

2016-04-01 Thread John Dammeyer

Which cable is the Van Damme?  
Can you post an ebay # or link?
Thanks
John

> -Original Message-
> From: andy pugh [mailto:bodge...@gmail.com]
> Sent: April-01-16 8:33 AM
> To: Enhanced Machine Controller (EMC)
> Subject: Re: [Emc-users] Modbus wiring
> 
> On 1 April 2016 at 16:22, Gene Heskett <ghesk...@wdtv.com> wrote:
> >> http://www.rapidonline.com/cables-connectors/belden-9841-data-
> cable-for-rs-485-51-6887
> >
> > Twisted pair is a transmission line and subject to all the vagaries of
> > load matching and such.
> >
> > That cables impedance is not listed there,
> 
> Yes it is. 120 Ohms.
> It is also specifically described as RS-485 cable.
> 
> But I also noticed that Van Damme list their DMX cable as suitable for
> RS-485 and that that is available from eBay at fairly low cost, so
> ordered some in on a "just in case" basis.
> It is also a pretty purple colour.
> 
> --
> 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, 1916
> 
> --
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Re: [Emc-users] Modbus wiring

On 1 April 2016 at 16:22, Gene Heskett  wrote:
>> http://www.rapidonline.com/cables-connectors/belden-9841-data-cable-for-rs-485-51-6887
>
> Twisted pair is a transmission line and subject to all the vagaries of
> load matching and such.
>
> That cables impedance is not listed there,

Yes it is. 120 Ohms.
It is also specifically described as RS-485 cable.

But I also noticed that Van Damme list their DMX cable as suitable for
RS-485 and that that is available from eBay at fairly low cost, so
ordered some in on a "just in case" basis.
It is also a pretty purple colour.

-- 
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, 1916

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Re: [Emc-users] Modbus wiring

On Friday 01 April 2016 07:02:14 andy pugh wrote:

> On 1 April 2016 at 11:46, Erik Christiansen  
wrote:
> > Incidentally, is that cable in the last picture twisted pair?
> > Shielded or no, is its characteristic impedance controlled?
>
> It is just what I cold find in Maplin that evening.
> I will see how well it works, and if there is a problem I can buy some
> of this:
> http://www.rapidonline.com/cables-connectors/belden-9841-data-cable-fo
>r-rs-485-51-6887

Twisted pair is a transmission line and subject to all the vagaries of 
load matching and such.

That cables impedance is not listed there, but should be on beldens own 
site. It looks quite similar to a black jacketed version used for 
balanced audio in a broadcast facility, with total usage often measured 
in miles.  And while its great cable for short runs, its characteristic 
impedance is only 60 ohms, which when driven by the usual amplifier 
expecting to find a "ma bell" style 600 ohm load, the cables capacitance 
can and will cause an high frequency rolloff.

So when I needed to re-design that amplifier rack because the existing 
shop made amps were power hungry and had a high failure rate, I turned 
them into op-amps which at unity or thereabouts gain, have an output 
impedance of almost zero ohms, then built it out to nominally 60 ohms 
with a 27 ohm resistor in series with each side of a driven line.

The difference in audio quality on the air could very easily be heard. 
The HF losses at the far end of a 180 foot run to an editing booth in 
the news room was only a small, almost unmeasureable loss at 15 
kilohertz. Perhaps .1 db. The old design had some .25% distortion, the 
new design was very close to .05%.  And I suspect that was at least half 
accounted for in the ohmage losses of the cable conductors.

With the amplifiers I could buy for broadcasting use at the time, that HF 
loss was almost 20 db in that same 180 feet of cable!

An rs485 circuit should be treated similarly, particularly at the load 
end if the run is long enough that you can see the echo step coming back 
when you're looking at the source end of the circuit.  With modern 
higher speed logic, that might be as little as 5 feet!  If a 62 ohm 
resistor across the two wires at the load end reduces the errors, that 
would be somewhat crude way to check if a scope isn't handy.

Cheers, Gene Heskett
-- 
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 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Genes Web page 

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Re: [Emc-users] Modbus wiring

On Friday 01 April 2016 06:46:02 Erik Christiansen wrote:

> On 30.03.16 17:13, andy pugh wrote:
> > In the end, I fitted a different VFD which has a pre-written HAL
> > driver. It also only has two connections for RS485, so is less
> > confusing. I found a way to connect the dongle to the motherboard
> > header:
> > https://forum.linuxcnc.org/forum/18-computer/30675-on-motherboard-mo
> >dbus-rs485-connection They are so cheap that I was prepared to go
> > through a couple experimenting, but it works fine.
>
> Andy,
>
> That is an inspired solution to the ungrounded dangling-dongle problem
> - well worth emulating.
>
> Incidentally, is that cable in the last picture twisted pair? Shielded
> or no, is its characteristic impedance controlled?
>
> I wonder if the dongles have a 110 or 120 ohm termination, or you need
> to add that yourself?
>
> It's usual to put a 100 ohm resistor in a ground wire run between
> ends, to take up a difference due to leakage, but not cause big ground
> loops. That's in data networks - I can't say for sure it's least
> imperfect in a machine situation.
>
> Erik

I've not had to resort to that but its a good idea. Use a 1/8 watt 100 
ohm resistor, and if the "ground loop" is strong enough to burn that 
out, then its safe to say that there are far more serious grounding 
problems in your present wiring config that need to be addressed as they 
are a shock hazard at best, and possibly lethal.

In my latest build, I have a bare twisted grounding wire connecting all 
the machine frames together. But I maintain also a "star" ground config 
in that all shielded cables have the shield connected to one point in 
the "electronics" box, and trimmed back, no connection, at the far end 
of the cable. That connection in the electronics box is also its case 
ground and the machine ground is there also.

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-- 
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 soap, ballot, jury, and ammo. Please use in that order."
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Re: [Emc-users] Modbus wiring

On 1 April 2016 at 11:46, Erik Christiansen  wrote:
>
> Incidentally, is that cable in the last picture twisted pair? Shielded
> or no, is its characteristic impedance controlled?

It is just what I cold find in Maplin that evening.
I will see how well it works, and if there is a problem I can buy some of this:
http://www.rapidonline.com/cables-connectors/belden-9841-data-cable-for-rs-485-51-6887

-- 
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, 1916

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Re: [Emc-users] Modbus wiring

2016-04-01 Thread Erik Christiansen

On 30.03.16 17:13, andy pugh wrote:
> In the end, I fitted a different VFD which has a pre-written HAL driver.
> It also only has two connections for RS485, so is less confusing.
> I found a way to connect the dongle to the motherboard header:
> https://forum.linuxcnc.org/forum/18-computer/30675-on-motherboard-modbus-rs485-connection
> They are so cheap that I was prepared to go through a couple
> experimenting, but it works fine.

Andy,

That is an inspired solution to the ungrounded dangling-dongle problem -
well worth emulating.

Incidentally, is that cable in the last picture twisted pair? Shielded
or no, is its characteristic impedance controlled?

I wonder if the dongles have a 110 or 120 ohm termination, or you need
to add that yourself?

It's usual to put a 100 ohm resistor in a ground wire run between ends,
to take up a difference due to leakage, but not cause big ground loops.
That's in data networks - I can't say for sure it's least imperfect in a
machine situation.

Erik

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Re: [Emc-users] Modbus wiring

2016-03-30 Thread andy pugh

On 9 February 2016 at 11:23, andy pugh  wrote:
> This is where things get iffy. Imagine that I have the 2-terminal
> dongle plugged into a laptop. What do I use for a gnd? Stuff a wire
> down the side of the USB connector? trap the wire in the hinge? :-)

In the end, I fitted a different VFD which has a pre-written HAL driver.
It also only has two connections for RS485, so is less confusing.
I found a way to connect the dongle to the motherboard header:
https://forum.linuxcnc.org/forum/18-computer/30675-on-motherboard-modbus-rs485-connection
They are so cheap that I was prepared to go through a couple
experimenting, but it works fine.

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Re: [Emc-users] Modbus wiring

2016-02-09 Thread andy pugh

On 9 February 2016 at 09:10, Erik Christiansen  wrote:
> What about 20 mA current loop? Sending an analogue signal as a current,
> rather than a voltage is reputed to be significantly more noise immune
> than sending it as a voltage.

I have a 7i49 with 6 channels of +/- 10V for servo drives that I am
not using. (the drives are actually connected via smart-serial) so
analogue voltage is very easy.

I have used analogue voltage on my other machines so far, and have not
noticed any critical lack of bandwidth :-)

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Re: [Emc-users] Modbus wiring

2016-02-09 Thread Erik Christiansen

On 08.02.16 13:16, andy pugh wrote:
> I need to connect to 8P8C connector on the VFD which has pins
> 1 A'
> 2 B'
> 3 A'
> 4 R
> 5 D
> 6 B'
> 7 DP5V
> 8 SG(GND)
> 
> Is that ever going to work? The YSB dongle seems deficient in
> terminals by at least 1, possibly 4...

The above looks a lot like full duplex, with A'B' being one differential
line, and A'B' being the other. (Seems to be too many ' there.) (We need
to know which is A, or the data is inverted.)

D,R are commonly the labels for Tx,Rx on the inboard side of an RS485
driver chip. What can they be doing on the external connector? (Unless
they're alternative single-ended inputs? Weird.)

Or is R the (100 ohm, ISTR) resistor which may be connected between
ends, in lieu of binding the GNDs, when there is up to the permissible
(7v ISTR) voltage offset? But then what's D?

The two-terminal dongle would be used for half-duplex, with separate
grounds, relying on less than 7v float.

On 08.02.16 22:42, Bertho Stultiens wrote:
> On 02/08/2016 10:12 PM, andy pugh wrote:
> > (And, back to the original question, how do I wire the 8 pins on the
> > VFD to the 2 pins on the adaptor?)
> 
> Ok, that looks reasonably "easy" and looks like rs422. It has two AA and
> BB connections, which are most likely a full duplex differential lines.
> If either AA or BB are opposite polarity, then you can be quite sure
> that it is differential (use a pull-up when measuring).

And that will identify whether it's AB which make a differential pair.

> Then you should be able to see on an oscilloscope if any line sends a
> peep on power-up. If so you have identified the rx/tx lines, the
> polarity of the tx line and the default baudrate.
> 
> Alternatively, the tx/rx lines should be identifiable using injection
> with a series resistor. The tx lines will stay put, whereas the rx lines
> will follow the injection.

Yes, if it's RS422, with the driver permanently enabled. But if it's
being tri-stated when not sending, it'll look just like an input.

On 08.02.16 15:19, Jerry Scharf wrote:
> This isn't the worst thing I've seen. Rs485 is a two wire differential half
> duplex signalling system. The doc says that it can run up to 38.4kbps.

In reverse gear. ;-) RS485 driver datasheets have for decades been
quoting 10 Mb/s for shortish lengths, and 1 Mb/s for half a km line
lengths, AFAIR. The wikipedia page talks of up to 35 Mbit/s up to 10 m
and 100 kbit/s at 1200 m. There are slowed-down low-interference driver
chips which will only do 2.5 Mb/s.

ISTR it was the physical layer of Appletalk, the network used by Apple
Macintosh, back when my beard wasn't grey.

For an undocumented VFD, untangling the Modbus trickery sounds like a
non-trivial project. Sending 1 Mb/s overs RS485 to an Arduino with D/A
sounds simpler. (PWM into a LPF might respond too slowly, once ripple is
filtered adequately?)

What about 20 mA current loop? Sending an analogue signal as a current,
rather than a voltage is reputed to be significantly more noise immune
than sending it as a voltage.

Erik

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Re: [Emc-users] Modbus wiring

2016-02-09 Thread andy pugh

On 9 February 2016 at 09:10, Erik Christiansen  wrote:
> The two-terminal dongle would be used for half-duplex, with separate
> grounds, relying on less than 7v float.

This is where things get iffy. Imagine that I have the 2-terminal
dongle plugged into a laptop. What do I use for a gnd? Stuff a wire
down the side of the USB connector? trap the wire in the hinge? :-)

Looking at Modbus specs,even the "two wire" version has a common. My
dongle doesn't.

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Re: [Emc-users] Modbus wiring

2016-02-09 Thread Lester Caine

On 08/02/16 13:16, andy pugh wrote:
> Is that ever going to work? The YSB dongle seems deficient in
> terminals by at least 1, possibly 4...

The quick answer here is YES the dongle is deficient in that it should
provide at least a screen connection rather than just data. The adapter
I use with the PTZ cameras has the duplex T and R pairs, but the T pair
also doubles as the 'D' which is multidrop I/O and there is a separate
earth to connect the screen. Certainly with the dongle you have linked
to, stuffing the earth wire down the USB connector seems the only
option, but also no provision to properly terminate a multidrop link.

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Re: [Emc-users] Modbus wiring

2016-02-09 Thread Erik Christiansen

On 09.02.16 11:23, andy pugh wrote:
> On 9 February 2016 at 09:10, Erik Christiansen  
> wrote:
> > The two-terminal dongle would be used for half-duplex, with separate
> > grounds, relying on less than 7v float.
> 
> This is where things get iffy. Imagine that I have the 2-terminal
> dongle plugged into a laptop. What do I use for a gnd? Stuff a wire
> down the side of the USB connector? trap the wire in the hinge? :-)

If the question has an element of seriousness, I'd suggest plugging a
naked USB connector into a spare USB port, with a soldered connection to
the shroud. That's less invasive than digging in to the earth wire in
the charger cable and then covering the violation with heatshrink
tubing. In either case, I'd interpose a 100 ohm resistor in the GND
link.

> Looking at Modbus specs,even the "two wire" version has a common. My
> dongle doesn't.

If twice the intended bus bias R values appear at both Tx and Rx ends,
then there will be a high resistance (e.g. 2720 ohm) DC connection
between GNDs and VCCs end-to-end, I figure. As the signal is
differential, that will have otherwise floating GNDs bobbing up and down
a bit, but held within common mode limits if there is no low impedance
source involved, I expect. It should work, at least some of the time.

But a 1999 "Circuit Cellar" "Designing RS485 Circuits" article says:
"To comply with the specification, all of the nodes must share a common
ground connection. This ground may be isolated from earth ground. The
ground wire provides a path for the current that results from small
imbalances in the balanced line. If the A and B outputs balance exactly
with equal, opposite currents, the two currents in the ground wire can-
cel each other out and the wire carries no current at all. In real life,
components don't balance perfectly; one driver will be a little stronger
and one receiver will have a slightly larger input impedance.

Without a common ground, the circuit may work, but the energy from the
imbalance has to go somewhere and may dissipate as electromagnetic
radiation. The RS-485 specification recommends connecting a 100-ohm
resistor of at least 0.5 W in series between each node's signal ground
and the network's ground wire, as Figure 1 shows. This way, if the
ground potentials of two nodes vary, the resistors limit the current in
the ground wire."

That seems to cover it.

Erik

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Re: [Emc-users] Modbus wiring

2016-02-08 Thread Todd Zuercher

If they are anything like the manufacturer of the drives I'm using with modbus. 
 You pretty much will have to contact them and have them send you the modbus 
manuals for the drive.  Googling up the drive did bring up a different manual 
that had a more ordinary looking pinout labeling for the modbus port on the 
drive. Probably only really need the 2 center wires 4&5.
1:A+
2:B-
3:A+
4:RXD0
5:TXD0
6:B-
7:VCC
8:AGND
Looked like there are some phone numbers on the address page on their site, or 
better yet send an email to the address listed in the manual 
i...@lovatoelectric.com
If I didn't need to control 8 vfds on that gang router instead of just 1 on a 
normal machine I would have never bothered with the modbus.  It was quite a 
pain to set up and I've never been able to get real good communication with 
them (slow with lots of errors.)

- Original Message -
From: "andy pugh" <bodge...@gmail.com>
To: "Enhanced Machine Controller (EMC)" <emc-users@lists.sourceforge.net>
Sent: Monday, February 8, 2016 7:22:17 PM
Subject: Re: [Emc-users] Modbus wiring

On 8 February 2016 at 23:10, Bertho Stultiens <ber...@vagrearg.org> wrote:
> I'd start with writing the manufacturer for the right docs.

I tried.
http://www.lovatoelectric.co.uk/Information-request/cnt
Appears to have a "Send" button that doesn't do anything.

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Re: [Emc-users] Modbus wiring

2016-02-08 Thread Lester Caine

On 09/02/16 05:20, Kirk Wallace wrote:
> (Bottom of page here:
> http://wiki.linuxcnc.org/cgi-bin/wiki.pl?AVR
> has it been five years already?)

Sounds about right ... must get some of these longer term projects
finished ;) That includes a nice modbus module for additional inputs and
control ...

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Re: [Emc-users] Modbus wiring

2016-02-08 Thread Dave Cole

On 2/8/2016 3:54 PM, andy pugh wrote:
> On 8 February 2016 at 20:34, Bertho Stultiens  wrote:
>> But, I should not hijack the thread with information theory...
> In theory Modbus should be better, but I don't have any information
> about the VFD interface.
>
> That's the version of information theory that matters to me here.

Hooking up two wires and a shield for an analog interface beats reverse 
engineering a drive even on a bad day.  ;-)

Andy, you would not have any problems using Modbus, but if the drive 
parameter to register interface is not documented, then you are shooting 
in the dark.
If they are not providing docs, chances are they have issues with the 
Modbus implementation and the interface is intentionally not fully 
documented.
It should not be that difficult, regardless of your view on information 
theory.  :-)

Dave

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Re: [Emc-users] Modbus wiring

2016-02-08 Thread Kirk Wallace

On 02/08/2016 12:54 PM, andy pugh wrote:
> On 8 February 2016 at 20:34, Bertho Stultiens  wrote:
>> But, I should not hijack the thread with information theory...
>
> In theory Modbus should be better, but I don't have any information
> about the VFD interface.
>
> That's the version of information theory that matters to me here.
>

I have several VFDs that do not have Modbus interfaces. One plan was to 
run Modbus to the VFD, but run it through an Arduino or AVR mounted to 
the front panel that would twiddle the VFD's control pins and run PWM 
for the analog speed pin. This is one of many things I haven't gotten 
around to finishing.

(Bottom of page here:
http://wiki.linuxcnc.org/cgi-bin/wiki.pl?AVR
has it been five years already?)



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[Emc-users] Modbus wiring

I am tempted to attempt to control the lathe VFD with Modbus.

I have one of these:
http://www.ebay.com/itm/CH340-USB-to-RS485-485-Converter-Adapter-Module-For-Win7-Linux-XP-Vista-/201258967189?hash=item2edbf82095:g:SDAAAOSw2s1UrPYd

I need to connect to 8P8C connector on the VFD which has pins
1 A'
2 B'
3 A'
4 R
5 D
6 B'
7 DP5V
8 SG(GND)

Is that ever going to work? The YSB dongle seems deficient in
terminals by at least 1, possibly 4...


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Re: [Emc-users] Modbus wiring

2016-02-08 Thread Sarah Armstrong

yea  it's a bit short on pins
i use these
http://www.ebay.co.uk/itm/Useful-80mm-USB-2-0-to-RS-485-RS-422-Serial-Converter-Adapter-Cable-ST-/151912461839

On 8 February 2016 at 13:16, andy pugh  wrote:

> I am tempted to attempt to control the lathe VFD with Modbus.
>
> I have one of these:
>
> http://www.ebay.com/itm/CH340-USB-to-RS485-485-Converter-Adapter-Module-For-Win7-Linux-XP-Vista-/201258967189?hash=item2edbf82095:g:SDAAAOSw2s1UrPYd
>
> I need to connect to 8P8C connector on the VFD which has pins
> 1 A'
> 2 B'
> 3 A'
> 4 R
> 5 D
> 6 B'
> 7 DP5V
> 8 SG(GND)
>
> Is that ever going to work? The YSB dongle seems deficient in
> terminals by at least 1, possibly 4...
>
>
> --
> atp
> If you can't fix it, you don't own it.
> http://www.ifixit.com/Manifesto
>
>
> --
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Re: [Emc-users] Modbus wiring

2016-02-08 Thread Dave Cole

On 2/8/2016 12:51 PM, andy pugh wrote:
> On 8 February 2016 at 17:40, Dave Cole  wrote:
>> RS485 is two wire, half duplex.
>> I think you have a RS422 connection that can run full duplex.
>> I don't recognize the D and R pins??Perhaps Data Ready and Request
>> to Send ??
>> Those aren't normally required for RS422.
> I am becoming increasingly tempted to forget the Modbus idea.
> Analogue control is realtime, for one thing.
>
> Also, I can't find any documentation of the Lovato VE1 modbus
> interface. No register numbers, and only the pinout info above.
Unless you need to change drive parameters it might be a waste of time.

Analog is easy.

Dave

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Re: [Emc-users] Modbus wiring

2016-02-08 Thread Dave Cole

RS485 is two wire, half duplex.
I think you have a RS422 connection that can run full duplex.
I don't recognize the D and R pins??Perhaps Data Ready and Request 
to Send ??
Those aren't normally required for RS422.

Dave

On 2/8/2016 8:16 AM, andy pugh wrote:
> I am tempted to attempt to control the lathe VFD with Modbus.
>
> I have one of these:
> http://www.ebay.com/itm/CH340-USB-to-RS485-485-Converter-Adapter-Module-For-Win7-Linux-XP-Vista-/201258967189?hash=item2edbf82095:g:SDAAAOSw2s1UrPYd
>
> I need to connect to 8P8C connector on the VFD which has pins
> 1 A'
> 2 B'
> 3 A'
> 4 R
> 5 D
> 6 B'
> 7 DP5V
> 8 SG(GND)
>
> Is that ever going to work? The YSB dongle seems deficient in
> terminals by at least 1, possibly 4...
>
>

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Re: [Emc-users] Modbus wiring

On 8 February 2016 at 17:40, Dave Cole  wrote:
> RS485 is two wire, half duplex.
> I think you have a RS422 connection that can run full duplex.
> I don't recognize the D and R pins??Perhaps Data Ready and Request
> to Send ??
> Those aren't normally required for RS422.

I am becoming increasingly tempted to forget the Modbus idea.
Analogue control is realtime, for one thing.

Also, I can't find any documentation of the Lovato VE1 modbus
interface. No register numbers, and only the pinout info above.

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Re: [Emc-users] Modbus wiring

On 8 February 2016 at 20:34, Bertho Stultiens  wrote:
> But, I should not hijack the thread with information theory...

In theory Modbus should be better, but I don't have any information
about the VFD interface.

That's the version of information theory that matters to me here.

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Re: [Emc-users] Modbus wiring

On 8 February 2016 at 21:04, Bertho Stultiens  wrote:

> I thought that ModBus was pretty standardized:

So which register do I write to to set output frequency?

Which register do I read to monitor motor current?

(And, back to the original question, how do I wire the 8 pins on the
VFD to the 2 pins on the adaptor?)

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Re: [Emc-users] Modbus wiring

2016-02-08 Thread Jerry Scharf

Bertho,

I agree with the sentiment that it is less than ideal to have something
that certainly has a local microprocessor that then creates an analog out
which you then read in. It's a lossy channel and subject to any number of
problems. That assumes you have the software skills and documentation
necessary to control the beast.

IMO, lacking a detailed description of the modbus commands, the digital
interface is best used as a door stop.

jerry


On Mon, Feb 8, 2016 at 11:07 AM, Bertho Stultiens 
wrote:

> On 02/08/2016 07:01 PM, Dave Cole wrote:
> >>> RS485 is two wire, half duplex.
> >>> I think you have a RS422 connection that can run full duplex.
> >>> I don't recognize the D and R pins??Perhaps Data Ready and Request
> >>> to Send ??
> >>> Those aren't normally required for RS422.
> >> I am becoming increasingly tempted to forget the Modbus idea.
> >> Analogue control is realtime, for one thing.
> >>
> >> Also, I can't find any documentation of the Lovato VE1 modbus
> >> interface. No register numbers, and only the pinout info above.
> > Unless you need to change drive parameters it might be a waste of time.
> >
> > Analog is easy.
>
> Analog is hard, very hard, if you want the same quality as the digital
> equivalent.
>
> There is a reason why there is a strong trend for going digital, which
> is primarily rooted in noise-immunity and signal recovery.
>
> An analog signal is, just like digital, bound by impedance of the
> transmission line. However, a slight imbalance in digital is
> recoverable, whereas an analog version will skew the result without
> possibility of (correct) recovery.
>
> Noise in analog will reduce the effective resolution, whereas noise in
> digital can be easily filtered and the resolution stays constant.
>
> Analog signals cannot be isolated easily and trying so results in
> awkward non-linearities that need to be compensated. A digital signal is
> easily isolated and does not require complex compensation.
>
>
> --
> Greetings Bertho
>
> (disclaimers are disclaimed)
>
>
> --
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Re: [Emc-users] Modbus wiring

On Mon, 8 Feb 2016 11:23:23 -0800
Jerry Scharf  wrote:

> Bertho,
> 
> I agree with the sentiment that it is less than ideal to have something
> that certainly has a local microprocessor that then creates an analog out
> which you then read in. It's a lossy channel and subject to any number of
> problems. That assumes you have the software skills and documentation
> necessary to control the beast.
> 
> IMO, lacking a detailed description of the modbus commands, the digital
> interface is best used as a door stop.
> 
> jerry

I would agree digital modbus should be the first but do not forget the bits per 
second needed.

115200 bits/second, 1kHz servo loop => 115.2 bits per servo loop equal to 
around 14 bytes per servo loop excluding overhead then RS-485 is probably half 
duplex.

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Re: [Emc-users] Modbus wiring

On 02/08/2016 09:01 PM, Nicklas Karlsson wrote:
>> I agree with the sentiment that it is less than ideal to have something
>> that certainly has a local microprocessor that then creates an analog out
>> which you then read in. It's a lossy channel and subject to any number of
>> problems. That assumes you have the software skills and documentation
>> necessary to control the beast.
>> IMO, lacking a detailed description of the modbus commands, the digital
>> interface is best used as a door stop.
> I would agree digital modbus should be the first but do not forget
> the bits per second needed.
>
> 115200 bits/second, 1kHz servo loop => 115.2 bits per servo loop
> equal to around 14 bytes per servo loop excluding overhead then
> RS-485 is probably half duplex.

You may need a higher throughput to compensate for round-trip-delay too
(group-delay in analog terms). Also, rs485 (multi-drop, half-duplex) may
be inferior to rs422 (point-to-point, full-duplex).

The Baudrate of the channel is not limited to 115k2, but can easily go
into multi-megabit. It is a question of matching requirements with the
correct hardware and software.

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Re: [Emc-users] Modbus wiring

> On 02/08/2016 08:52 PM, Nicklas Karlsson wrote:
> >> Noise in analog will reduce the effective resolution, whereas noise in
> >> digital can be easily filtered and the resolution stays constant.
> >> Analog signals cannot be isolated easily and trying so results in
> >> awkward non-linearities that need to be compensated. A digital signal is
> >> easily isolated and does not require complex compensation.
> > 
> > Yes analog signals certainly have problems in particular with
> > isolation barriers and noise but replacing with high resolution and
> > bandwidth require quite a lot of bits per second.
> 
> It is a misconception, to think that the bandwidth of an analog channel
> is higher than a digital one. It is actually reversed, where the
> /effective/ bandwidth of a digital channel is higher than an equivalent
> analog channel.
> 
> The number of bits required goes to the root of Shannon's information
> theory. We see how effective it is in our daily life everywhere and it
> is better than analog.
> 
> Telephony has been digitalized completely today. Television has
> transitioned from analog to digital, freeing more than 50% of the
> bandwidth, while increasing the number of channels. Radio will follow
> (currently running parallel).
> 
> 
> -- 
> Greetings Bertho

Greatest advantage with digital is lossless transmission. Then analog level 
start to detoriate it may be brought back to digital and resent for examle then 
changing the medium it is sent thru.


With a sample frequency of 1kHz up to maximum 500Hz analog signal is possible. 
Fast control loop require quite a lot of bits per second and good real time 
performance. Then it come to RS-232 and RS-485 limitations might be hit.

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Re: [Emc-users] Modbus wiring

On 02/08/2016 09:54 PM, andy pugh wrote:
> On 8 February 2016 at 20:34, Bertho Stultiens  wrote:
>> But, I should not hijack the thread with information theory...
> In theory Modbus should be better, but I don't have any information
> about the VFD interface.
> 
> That's the version of information theory that matters to me here.

I thought that ModBus was pretty standardized:
http://www.interlog.com/~speff/usefulinfo/modbus_protocol.pdf
(link from wikipedia's modbus entry)

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Re: [Emc-users] Modbus wiring

On 02/08/2016 09:12 PM, Peter C. Wallace wrote:
>> The number of bits required goes to the root of Shannon's information
>> theory. We see how effective it is in our daily life everywhere and it
>> is better than analog.
>>
>> Telephony has been digitalized completely today. Television has
>> transitioned from analog to digital, freeing more than 50% of the
>> bandwidth, while increasing the number of channels. Radio will follow
>> (currently running parallel).
> 
> I would disagree here, many high speed transmission systems mix
> analog and digital techniques to get a higher bandwsith at a lower 
> symbol rate (100BT ethernet uses MLT3 (3 level) and 1G Ethernet uses
> PAM5 with 5 signal levels)

Actually, digital channels send X bits per symbol for X > 0. F.ex.
256-QAM, used in digital TV broadcasts, sends 8 bits for each
transmitted symbol. Standard async serial coding (8n1) sends effective
only 0.8 bit per symbol.

You are right that there is a combination of analog/digital here, but
the fact is that all signals are analog if you get to the bottom of it.
It is the digital /interpretation/ of the signal that enables you to
gain large benefits.

Information theory states that the recovery of the signal is dependent
on the coding of the signal. That is, coding at several levels (hardware
and software). For example using predictive filters , compression and
FEC. The theory does not state how the coding is performed, merely that
there is a limit to what you can do. And that limit is a very large number.

But, I should not hijack the thread with information theory...

-- 
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Re: [Emc-users] Modbus wiring

On 02/08/2016 10:12 PM, andy pugh wrote:
>> I thought that ModBus was pretty standardized:
> So which register do I write to to set output frequency?

Do you have the original documentation of the VFD? I guess not.
Do you have any "old" VFD control or test software, If you have, you can
reverse engineer the commands quite easily. If not, you have to do
(quite a bit) more work.

> Which register do I read to monitor motor current?

Try and try again, or get a hold of the documentation. ;-)

More seriously, fuzzing or educated guessing would probably be my way of
finding the right info.

> (And, back to the original question, how do I wire the 8 pins on the
> VFD to the 2 pins on the adaptor?)

Ok, that looks reasonably "easy" and looks like rs422. It has two AA and
BB connections, which are most likely a full duplex differential lines.
If either AA or BB are opposite polarity, then you can be quite sure
that it is differential (use a pull-up when measuring).

Then you should be able to see on an oscilloscope if any line sends a
peep on power-up. If so you have identified the rx/tx lines, the
polarity of the tx line and the default baudrate.

Alternatively, the tx/rx lines should be identifiable using injection
with a series resistor. The tx lines will stay put, whereas the rx lines
will follow the injection.

Then, when you have identified the rx lines, you start sending junk
(fuzzing) and see what the tx lines do. This way you can identify
polarity and baudrate.

>From there you can start sending informational modbus commands and see
what happens.

The 5V line is useful for an in-line isolator. The R and D lines are
either feedback or feed-forward lines. You can normally identify
input/output by injection with a series resistor and see if the line
will bulge in the direction you want it to.

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Re: [Emc-users] Modbus wiring

> On 8 February 2016 at 17:40, Dave Cole  wrote:
> > RS485 is two wire, half duplex.
> > I think you have a RS422 connection that can run full duplex.
> > I don't recognize the D and R pins??Perhaps Data Ready and Request
> > to Send ??
> > Those aren't normally required for RS422.
> 
> I am becoming increasingly tempted to forget the Modbus idea.
> Analogue control is realtime, for one thing.

Quite a lot of digital bits per second is required to replace the bandwidth in 
an analog signal even for slow operational amplifiers.

RS-485 require termination and driver may need supply voltage both side of the 
isolation barrier if there is one. Figure of the termination of way down this 
link https://en.wikipedia.org/wiki/RS-485


Nicklas Karlsson

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Re: [Emc-users] Modbus wiring

On 02/08/2016 07:01 PM, Dave Cole wrote:
>>> RS485 is two wire, half duplex.
>>> I think you have a RS422 connection that can run full duplex.
>>> I don't recognize the D and R pins??Perhaps Data Ready and Request
>>> to Send ??
>>> Those aren't normally required for RS422.
>> I am becoming increasingly tempted to forget the Modbus idea.
>> Analogue control is realtime, for one thing.
>>
>> Also, I can't find any documentation of the Lovato VE1 modbus
>> interface. No register numbers, and only the pinout info above.
> Unless you need to change drive parameters it might be a waste of time.
> 
> Analog is easy.

Analog is hard, very hard, if you want the same quality as the digital
equivalent.

There is a reason why there is a strong trend for going digital, which
is primarily rooted in noise-immunity and signal recovery.

An analog signal is, just like digital, bound by impedance of the
transmission line. However, a slight imbalance in digital is
recoverable, whereas an analog version will skew the result without
possibility of (correct) recovery.

Noise in analog will reduce the effective resolution, whereas noise in
digital can be easily filtered and the resolution stays constant.

Analog signals cannot be isolated easily and trying so results in
awkward non-linearities that need to be compensated. A digital signal is
easily isolated and does not require complex compensation.

-- 
Greetings Bertho

(disclaimers are disclaimed)

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Re: [Emc-users] Modbus wiring

On 02/08/2016 08:52 PM, Nicklas Karlsson wrote:
>> Noise in analog will reduce the effective resolution, whereas noise in
>> digital can be easily filtered and the resolution stays constant.
>> Analog signals cannot be isolated easily and trying so results in
>> awkward non-linearities that need to be compensated. A digital signal is
>> easily isolated and does not require complex compensation.
> 
> Yes analog signals certainly have problems in particular with
> isolation barriers and noise but replacing with high resolution and
> bandwidth require quite a lot of bits per second.

It is a misconception, to think that the bandwidth of an analog channel
is higher than a digital one. It is actually reversed, where the
/effective/ bandwidth of a digital channel is higher than an equivalent
analog channel.

The number of bits required goes to the root of Shannon's information
theory. We see how effective it is in our daily life everywhere and it
is better than analog.

Telephony has been digitalized completely today. Television has
transitioned from analog to digital, freeing more than 50% of the
bandwidth, while increasing the number of channels. Radio will follow
(currently running parallel).

-- 
Greetings Bertho

(disclaimers are disclaimed)

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Re: [Emc-users] Modbus wiring

On 02/08/2016 08:23 PM, Jerry Scharf wrote:
> I agree with the sentiment that it is less than ideal to have something
> that certainly has a local microprocessor that then creates an analog out
> which you then read in. It's a lossy channel and subject to any number of
> problems. That assumes you have the software skills and documentation
> necessary to control the beast.
> IMO, lacking a detailed description of the modbus commands, the digital
> interface is best used as a door stop.

You are completely right that digital requires a different skill-set and
quite a lot of documentation. Lacking either makes it difficult.

It may also be an opportunity to change something for the better.
Creating documentation, doing reverse engineering, making an open
version of the hardware and software, etc.. Collaboration is probably
the keyword here, just like LCNC is developed.

That is, of course, a long term goal. You can always use a stop-gap
solution to fix your current problem. But it would be nice to make it
better ;-)

-- 
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(disclaimers are disclaimed)

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Re: [Emc-users] Modbus wiring

2016-02-08 Thread Peter C. Wallace

On Mon, 8 Feb 2016, Bertho Stultiens wrote:

> Date: Mon, 8 Feb 2016 21:03:44 +0100
> From: Bertho Stultiens <ber...@vagrearg.org>
> 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] Modbus wiring
> 
> On 02/08/2016 08:52 PM, Nicklas Karlsson wrote:
>>> Noise in analog will reduce the effective resolution, whereas noise in
>>> digital can be easily filtered and the resolution stays constant.
>>> Analog signals cannot be isolated easily and trying so results in
>>> awkward non-linearities that need to be compensated. A digital signal is
>>> easily isolated and does not require complex compensation.
>>
>> Yes analog signals certainly have problems in particular with
>> isolation barriers and noise but replacing with high resolution and
>> bandwidth require quite a lot of bits per second.
>
> It is a misconception, to think that the bandwidth of an analog channel
> is higher than a digital one. It is actually reversed, where the
> /effective/ bandwidth of a digital channel is higher than an equivalent
> analog channel.
>
> The number of bits required goes to the root of Shannon's information
> theory. We see how effective it is in our daily life everywhere and it
> is better than analog.
>
> Telephony has been digitalized completely today. Television has
> transitioned from analog to digital, freeing more than 50% of the
> bandwidth, while increasing the number of channels. Radio will follow
> (currently running parallel).


I would disagree here, many  high speed transmission systems
mix analog and digital techniques to get a higher bandwsith at a lower 
symbol rate (100BT ethernet uses MLT3 (3 level) and 1G Ethernet uses PAM5 with 
5 signal levels)

>
>
> -- 
> Greetings Bertho
>
> (disclaimers are disclaimed)
>
> --
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>

Peter Wallace
Mesa Electronics

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Re: [Emc-users] Modbus wiring

> On 02/08/2016 07:01 PM, Dave Cole wrote:
> >>> RS485 is two wire, half duplex.
> >>> I think you have a RS422 connection that can run full duplex.
> >>> I don't recognize the D and R pins??Perhaps Data Ready and Request
> >>> to Send ??
> >>> Those aren't normally required for RS422.
> >> I am becoming increasingly tempted to forget the Modbus idea.
> >> Analogue control is realtime, for one thing.
> >>
> >> Also, I can't find any documentation of the Lovato VE1 modbus
> >> interface. No register numbers, and only the pinout info above.
> > Unless you need to change drive parameters it might be a waste of time.
> > 
> > Analog is easy.
> 
> Analog is hard, very hard, if you want the same quality as the digital
> equivalent.
> 
> There is a reason why there is a strong trend for going digital, which
> is primarily rooted in noise-immunity and signal recovery.
> 
> An analog signal is, just like digital, bound by impedance of the
> transmission line. However, a slight imbalance in digital is
> recoverable, whereas an analog version will skew the result without
> possibility of (correct) recovery.
> 
> Noise in analog will reduce the effective resolution, whereas noise in
> digital can be easily filtered and the resolution stays constant.
> 
> Analog signals cannot be isolated easily and trying so results in
> awkward non-linearities that need to be compensated. A digital signal is
> easily isolated and does not require complex compensation.

Yes analog signals certainly have problems in particular with isolation 
barriers and noise but replacing with high resolution and bandwidth require 
quite a lot of bits per second.


Nicklas Karlsson

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Re: [Emc-users] Modbus wiring

On 8 February 2016 at 21:42, Bertho Stultiens  wrote:

> Try and try again, or get a hold of the documentation. ;-)

The documentation is silent on the subject:
http://www.lovatoelectric.com/Single-phase-supply-200-240VAC-50-60Hz-EMC-suppressor-built-in-PNP-24VDC-programmable-inputs/150005010/spd


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Re: [Emc-users] Modbus wiring

On 8 February 2016 at 22:20, Bertho Stultiens  wrote:

> My best guess is that they have mapped the entire register space from
> the front-panel config (page 4-9 and forward), as documented, to the
> communications register map. That should be possible to test with a few
> read commands.

I thought of that, but they only document writable parameters. None of
them look like a likely place to read currents or voltages.



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Re: [Emc-users] Modbus wiring

On 02/08/2016 11:03 PM, andy pugh wrote:
>> Try and try again, or get a hold of the documentation. ;-)
> 
> The documentation is silent on the subject:
> http://www.lovatoelectric.com/Single-phase-supply-200-240VAC-50-60Hz-EMC-suppressor-built-in-PNP-24VDC-programmable-inputs/150005010/spd

Interesting...

The doc
(http://www.lovatoelectric.com/HandlerDoc.ashx?s=I365GB12_12.pdf=119)
says it is a RS485 line. I guess that A+/A+ are connected and B-/B- too
for easy chaining.

But page 3-13 describes a plain serial connection too (pins 4/5
RXD0/TXD0). That is the test entry point (needs to be tested for 5V or
RS232 levels). It may be the console or an alternative interface. You
should be get some info from there.

My best guess is that they have mapped the entire register space from
the front-panel config (page 4-9 and forward), as documented, to the
communications register map. That should be possible to test with a few
read commands.

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Re: [Emc-users] Modbus wiring

On 8 February 2016 at 23:10, Bertho Stultiens  wrote:
>> I thought of that, but they only document writable parameters. None of
>> them look like a likely place to read currents or voltages.
>
> Often you have r/w registers, where you read a measured value and write
> a parameter. However, you are right that it is a difficult call.

Also, as I have never used Modbus, this seems like an unnecessarily
difficult starting point.

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Re: [Emc-users] Modbus wiring

On 8 February 2016 at 23:10, Bertho Stultiens  wrote:
> I'd start with writing the manufacturer for the right docs.

I tried.
http://www.lovatoelectric.co.uk/Information-request/cnt
Appears to have a "Send" button that doesn't do anything.

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Re: [Emc-users] Modbus wiring

On 02/08/2016 11:56 PM, andy pugh wrote:
>> My best guess is that they have mapped the entire register space from
>> the front-panel config (page 4-9 and forward), as documented, to the
>> communications register map. That should be possible to test with a few
>> read commands.
> 
> I thought of that, but they only document writable parameters. None of
> them look like a likely place to read currents or voltages.

Often you have r/w registers, where you read a measured value and write
a parameter. However, you are right that it is a difficult call.

I'd start with writing the manufacturer for the right docs. If that
fails then I'd scan the registers and see what returns under "known"
conditions and then correlate.


-- 
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Re: [Emc-users] Modbus wiring

2016-02-08 Thread Jerry Scharf

Andy,

This isn't the worst thing I've seen. Rs485 is a two wire differential half
duplex signalling system. The doc says that it can run up to 38.4kbps.

So you one 1 wire to the plus of the master and the vfd and the other wire
to the minus. It will run on anything twisted that is better than tin cans
and wet string. Ground one side of the shield if there is one. Set the
master and slave to the same baud rate (38.4k).

What are you planning on using for the RS485 master interface? You can get
things that shift levels from rs232 serial or you can get boxes that sit on
a network and talk rs485 out the back. I use the network ones personally.

Are you familar with talking modbus? There is an address for each slave,
them a command (usually read register or preset register,) then the start
and range of registers, then the data (either there or back) and finally a
CRC16. All the stuff is sent as 8 bit data as two hex characters encoded in
ascii. The idea is that the master sends out the data and then the slave
responds. No one talks without the master talking first.

I would assume the numbers in the document (like 12-00) is the modbus
register address. It can take a little trial and error to get this right.

I hope that helps.

jerry

On Mon, Feb 8, 2016 at 2:03 PM, andy pugh  wrote:

> On 8 February 2016 at 21:42, Bertho Stultiens  wrote:
>
> > Try and try again, or get a hold of the documentation. ;-)
>
> The documentation is silent on the subject:
>
> http://www.lovatoelectric.com/Single-phase-supply-200-240VAC-50-60Hz-EMC-suppressor-built-in-PNP-24VDC-programmable-inputs/150005010/spd
>
>
> --
> atp
> If you can't fix it, you don't own it.
> http://www.ifixit.com/Manifesto
>
>
> --
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Re: [Emc-users] Modbus wiring

2016-02-08 Thread Gregg Eshelman

On 2/8/2016 1:03 PM, Bertho Stultiens wrote:

> Telephony has been digitalized completely today. Television has
> transitioned from analog to digital, freeing more than 50% of the
> bandwidth, while increasing the number of channels. Radio will follow
> (currently running parallel).

There have been digital radio broadcasts in the USA for quite some time, 
but unlike television the FCC has not set a date to end analog radio 
broadcasting.

The "legacy" problem is even larger than it was for TV, with no easy way 
to adapt any old radio to digital. Adoption rate of digital radio has 
been very slow.

If the FCC had a mandate for every receiver manufactured after a certain 
date be required to have a digital tuner, the radio stations would have 
been upgrading to digital.

Then once enough of a majority of actively used receivers had digital 
capability, analog broadcasts could be shut down - making all those old 
analog radios into paperweights and doorstops.

One digital radio thing that has been added to many newer receivers, 
especially for automotive use, is Radio Data Service that can send 
information like song titles or road construction info and emergency 
warnings.

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[Emc-users] Modbus RS-485 Connection with Mesa?

I'm looking at controlling a X-Z gantry system w/ LinuxCNC (well really HAL
and some code). Operator pushes a button and the gantry moves between two
baths, waiting for pre-set seconds per bath. The positions are set and do
not change.

I was thinking of using a Mesa 5i25-7i76 combo and maybe a 7i32 1.5/3Amp or
another off-the-shelf stepper driver. There's no-magic needed for this. I
need some I/O for limits, home, inputs, outputs, etc. I realize the 7i76
is overkill for axis count, but I might want to expand to 4 axes later.

I would take one of the GUI interfaces (touchy or axis, etc) and make my
own suitable interface (easier said than done, possibly).

The bath has a Love temp controller (16A2133-996) that can communicate
Modbus RS-485. The 7i76 has RS-422 serial and the PC would have a RS-232
port. What's the best way to get to RS-485? I could use a RS-232 to
RS-485 converter like this one from advantech:
http://www.mouser.com/ProductDetail/Advantech/ADAM-4561-CE/?qs=%2fha2pyFaduhMyuR96x%252bdp4DnBDFhtESzKcpNyIUxvYPu1PngEfDtkA%3d%3d

I thought maybe someone would have a suggestion? Might the mesa smart
serial RS-422 be able to work someway?

Regards,
Mark

PS. Considering my monitor turning off issues (previous posts), I'm second
guessing using LinuxCNC/hal for this, but I'm a glutton for punishment..
You just can't beat the price/feature linuxCNC.
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Re: [Emc-users] Modbus RS-485 Connection with Mesa?

Seb - How do you respond so fast?!

The love controller has a -995 option, which is RS232. But, there are 2
controllers and there's no addressing for the rs-232 version from what I
saw. I thought maybe you could daisy chain them, but seems you can only
address the RS-485 version.

On the Automation direct GS2 VFD, that was nice because it had a rs-485 or
rs-232 option selectable.

PS - what reader do you use for this mailing list to get the inserted?
I simply have been using gmail and recall posts a long time ago on better
readers, but I couldn't find it when I searched? Also, I think one of the
reader will keep the posts in one thread.

Thanks,
Mark

On 4/1/15 10:05 AM, Mark Johnsen wrote:
The bath has a Love temp controller (16A2133-996) that can communicate
Modbus RS-485. The 7i76 has RS-422 serial and the PC would have a RS-232
port. What's the best way to get to RS-485? I could use a RS-232 to
RS-485 converter like this one from advantech:

http://www.mouser.com/ProductDetail/Advantech/ADAM-4561-CE/?qs=%2fha2pyFaduhMyuR96x%252bdp4DnBDFhtESzKcpNyIUxvYPu1PngEfDtkA%3d%3d

I thought maybe someone would have a suggestion? Might the mesa smart
serial RS-422 be able to work someway?

A lot of modbus devices will accept RS232. I run modbus from LinuxCNC
to a couple of VFDs over USB-to-RS232 adapters, inexpensive works great.

--
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Re: [Emc-users] Modbus RS-485 Connection with Mesa?

2015-04-01 Thread Sebastian Kuzminsky

On 4/1/15 10:05 AM, Mark Johnsen wrote:
 The bath has a Love temp controller (16A2133-996) that can communicate
 Modbus RS-485.  The 7i76 has RS-422 serial and the PC would have a RS-232
 port.  What's the best way to get to RS-485?  I could use a RS-232 to
 RS-485 converter like this one from advantech:
 http://www.mouser.com/ProductDetail/Advantech/ADAM-4561-CE/?qs=%2fha2pyFaduhMyuR96x%252bdp4DnBDFhtESzKcpNyIUxvYPu1PngEfDtkA%3d%3d

 I thought maybe someone would have a suggestion?  Might the mesa smart
 serial RS-422 be able to work someway?

A lot of modbus devices will accept RS232.  I run modbus from LinuxCNC 
to a couple of VFDs over USB-to-RS232 adapters, inexpensive  works great.


-- 
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Re: [Emc-users] Modbus RS-485 Connection with Mesa?

2015-04-01 Thread Todd Zuercher

I have a gang router running Linuxcnc and controlling 8 VFDs through one 
USB-RS485 and the generic Mb2hal driver.

- Original Message -
From: alex chiosso achio...@gmail.com
To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net
Sent: Wednesday, April 1, 2015 5:11:21 PM
Subject: Re: [Emc-users] Modbus RS-485 Connection with Mesa?

I do believe that you can use LCNC with a usb to RS485 converter and the
Modbus protocol by ClassicLadder softplc built into LCNC or the mb2hal
component.

Alex
Il giorno 01/apr/2015 23:04, Mark Johnsen m...@ijohnsen.com ha scritto:

 Alex,

 Yes, the application is industrial grade, but it is quite simple (2 axes of
 motion).  I only need 1 modbus network to two temp controllers.  Since
 there are 2, that rules out '1' RS-232 network, but I can use '1' RS-485
 network.  Or Seb's USB setup would work.

 I did see on the mesa site the 7I34 8 channel RS-422/485 interface for
 Anything I/O.  I would think that would work.

 Your comment about industrial grade is my concern about using LinuxCNC at
 all.  I figure I can try it and if I run into issues I can slap in a brick
 PLC (omron, panasonic, etc) w/ some option cards, but that is much more
 expensive and less flexible in the long run.  I look at LinuxCNC w/ so much
 potential and it combines the control and HMI into one piece.  I realize it
 is not a traditional industrial control solution.  If you think I'm crazy
 for doing this, let me know now...

 SEB - I can embrace USB.  I just thought that was looked down upon due to
 the lack of real-time nature of USB ports?   Although, I don't really need
 real-time here for temp control.  Just updating and current temp feedback.

 I think for the price of the mesa board, that seems like a good option and
 more trustworthy than the Amazon USB part. Just my 2 cents..

 Thanks all for your feedback,
 Mark

 Hi Mark .
 Be careful with this kind of adapters because they are not optocoupled .
 If your application is an industrial grade I will spend some more money and
 buy something like the Advantech converter/adapter you linked above.
 Do you really need to have two separate Modbus network ?

 Alex

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Re: [Emc-users] Modbus RS-485 Connection with Mesa?

I got , but I had to reply, edit the subject and then delete all the
text I didn't want.  I suppose I could have copied it as well.  Unless
it's easy, this is better than I had...

Thanks.



 On 1 April 2015 at 17:26, Mark Johnsen m...@ijohnsen.com wrote:
 PS - what reader do you use for this mailing list to get the  inserted?
 I simply have been using gmail and recall posts a long time ago on better
 readers, but I couldn't find it when I searched?


 Click in the message you want to reply to so that a blue bar appears
 next to the sender image.

I looked all around for a blue bar and didn't see that nor a sender
image?  I'm using gmail for Apps and I have 'categories' turned on.
Maybe something different in the setup.

 Then select the text you want to include.
 The press the reply button, or if you have enabled keyboard short-cuts
 press the A key (reply All) or R key (Reply)

I couldn't easily get out the

 Then in the bottom left corner of the reply pane drop-down the little
 arrow next to the bin and select Plain text mode

I found that!  It did show the .  Nice...


 Gmail doesn't necessarily display the  but does insert them.

 --
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 If you can't fix it, you don't own it.
 http://www.ifixit.com/Manifesto



 --

 Message: 6
 Date: Wed, 1 Apr 2015 19:59:53 -0400
 From: Jeremy Jones sp01jjo...@gmail.com
 Subject: Re: [Emc-users] Mesa cards visual documentation
 To: Enhanced Machine Controller (EMC)
 emc-users@lists.sourceforge.net
 Message-ID:
 CAEOnsKy=NR5+A8vK1Nv=n4uaecqvn2dev5rqi8crfvplmpj...@mail.gmail.com
 Content-Type: text/plain; charset=UTF-8

 I took the picture in the manual of my 7i76 and laminated it. Then as I
 hooked stuff up I sharpied on there each pin and stuck it in with the
 machine. This way I know what's what moving forward.

 On Wed, Apr 1, 2015 at 5:58 PM, andy pugh bodge...@gmail.com wrote:

 On 1 April 2015 at 21:39, Marius Alksnys marius.alks...@gmail.com wrote:
  Is there any more visual documentation available for mesa cards than
  main manual?

 You mean more detailed than 7i77man.pdf ?

 With many of the Mesa cards the HAL pin names that correspond to
 physical pins are governed by the firmware. This is less the case with
 the 7i77, though you can alter a few things with the software modes.

 --
 atp
 If you can't fix it, you don't own it.
 http://www.ifixit.com/Manifesto


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 sponsored
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 all
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 to
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 --

 Message: 7
 Date: Wed, 1 Apr 2015 23:10:46 -0400 (EDT)
 From: Todd  Zuercher zuerc...@embarqmail.com
 Subject: Re: [Emc-users] Modbus RS-485 Connection with Mesa?
 To: Enhanced Machine Controller (EMC)
 emc-users@lists.sourceforge.net
 Message-ID:
 1922233235.59027099.1427944246852.javamail.r...@embarqmail.com
 Content-Type: text/plain; charset=utf-8

 I have a gang router running Linuxcnc and controlling 8 VFDs through one 
 USB-RS485 and the generic Mb2hal driver.

 - Original Message -
 From: alex chiosso achio...@gmail.com
 To: Enhanced Machine Controller (EMC) emc-users@lists.sourceforge.net
 Sent: Wednesday, April 1, 2015 5:11:21 PM
 Subject: Re: [Emc-users] Modbus RS-485 Connection with Mesa?

 I do believe that you can use LCNC with a usb to RS485 converter and the
 Modbus protocol by ClassicLadder softplc built into LCNC or the mb2hal
 component.

 Alex
 Il giorno 01/apr/2015 23:04, Mark Johnsen m...@ijohnsen.com ha scritto:

 Alex,

 Yes, the application is industrial grade, but it is quite simple (2 axes of
 motion).  I only need 1 modbus network to two temp controllers.  Since
 there are 2, that rules out '1' RS-232 network, but I can use '1' RS-485
 network.  Or Seb's USB setup would work.

 I did see on the mesa site the 7I34 8 channel RS-422/485 interface for
 Anything I/O.  I would think that would work.

 Your comment about industrial grade is my concern about using LinuxCNC at
 all.  I figure I can try it and if I run into issues I can slap in a brick
 PLC (omron, panasonic, etc) w/ some option cards, but that is much more
 expensive and less flexible in the long run.  I look at LinuxCNC w/ so much
 potential and it combines the control and HMI into one piece.  I realize it
 is not a traditional industrial control solution.  If you think I'm crazy
 for doing this, let me know now

Re: [Emc-users] Modbus RS-485 Connection with Mesa?

2015-04-01 Thread Wesley Moore

Mark,

Not sure if this helps or not. But for various control systems I use Moxa
device servers for Ethernet to RS232/422/485. I talk to them over TCP/IP, but
it can give you a simple telnet port to the device on the other end.

http://www.moxa.com/Serial_Connectivity/Index.aspx

Wesley

- Original Message -
From: Mark Johnsen m...@ijohnsen.com
To: Enhanced Machine Controller emc-users@lists.sourceforge.net
Sent: Wednesday, April 1, 2015 12:05:54 PM
Subject: [Emc-users] Modbus RS-485 Connection with Mesa?

I would take one of the GUI interfaces (touchy or axis, etc) and make my
own suitable interface (easier said than done, possibly).

I thought maybe someone would have a suggestion? Might the mesa smart
serial RS-422 be able to work someway?

Regards,
Mark

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Re: [Emc-users] Modbus RS-485 Connection with Mesa?

2015-04-01 Thread Sebastian Kuzminsky

On 4/1/15 10:26 AM, Mark Johnsen wrote:
 The love controller has a -995 option, which is RS232.  But, there are 2
 controllers and there's no addressing for the rs-232 version from what I
 saw.  I thought maybe you could daisy chain them, but seems you can only
 address the RS-485 version.

Right, RS232 is point-to-point, with no good options for multi-point 
expansion.

Once you embrace USB you could get a $10 USB hub and two USB-toRS232 
adapters.

Or possibly something like this could work (i have no experience with 
it): 
http://www.amazon.com/KEDSUM%C2%AE-Converter-Adapter-ch340T-Support/dp/B009SIDMNM


 PS - what reader do you use for this mailing list to get the  inserted?
 I simply have been using gmail and recall posts a long time ago on better
 readers, but I couldn't find it when I searched?  Also, I think one of the
 reader will keep the posts in one thread.

I use Thunderbird (called icedove on debian).


-- 
Sebastian Kuzminsky

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Re: [Emc-users] Modbus RS-485 Connection with Mesa?

2015-04-01 Thread alex chiosso

Hi Mark .
Be careful with this kind of adapters because they are not optocoupled .
If your application is an industrial grade I will spend some more money and
buy something like the Advantech converter/adapter you linked above.
Do you really need to have two separate Modbus network ?

Alex

On Wed, Apr 1, 2015 at 6:39 PM, Sebastian Kuzminsky s...@highlab.com wrote:

 On 4/1/15 10:26 AM, Mark Johnsen wrote:
  The love controller has a -995 option, which is RS232.  But, there are 2
  controllers and there's no addressing for the rs-232 version from what I
  saw.  I thought maybe you could daisy chain them, but seems you can only
  address the RS-485 version.

 Right, RS232 is point-to-point, with no good options for multi-point
 expansion.

 Once you embrace USB you could get a $10 USB hub and two USB-toRS232
 adapters.

 Or possibly something like this could work (i have no experience with
 it):

 http://www.amazon.com/KEDSUM%C2%AE-Converter-Adapter-ch340T-Support/dp/B009SIDMNM


  PS - what reader do you use for this mailing list to get the 
 inserted?
  I simply have been using gmail and recall posts a long time ago on better
  readers, but I couldn't find it when I searched?  Also, I think one of
 the
  reader will keep the posts in one thread.

 I use Thunderbird (called icedove on debian).


 --
 Sebastian Kuzminsky


 --
 Dive into the World of Parallel Programming The Go Parallel Website,
 sponsored
 by Intel and developed in partnership with Slashdot Media, is your hub for
 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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 Emc-users@lists.sourceforge.net
 https://lists.sourceforge.net/lists/listinfo/emc-users

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Re: [Emc-users] Modbus RS-485 Connection with Mesa?

2015-04-01 Thread andy pugh

On 1 April 2015 at 17:26, Mark Johnsen m...@ijohnsen.com wrote:
 PS - what reader do you use for this mailing list to get the  inserted?
 I simply have been using gmail and recall posts a long time ago on better
 readers, but I couldn't find it when I searched?


Click in the message you want to reply to so that a blue bar appears
next to the sender image.
Then select the text you want to include.
The press the reply button, or if you have enabled keyboard short-cuts
press the A key (reply All) or R key (Reply)
Then in the bottom left corner of the reply pane drop-down the little
arrow next to the bin and select Plain text mode

Gmail doesn't necessarily display the  but does insert them.

-- 
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto

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Re: [Emc-users] Modbus RS-485 Connection with Mesa?

2015-04-01 Thread alex chiosso

I do believe that you can use LCNC with a usb to RS485 converter and the
Modbus protocol by ClassicLadder softplc built into LCNC or the mb2hal
component.

Alex
Il giorno 01/apr/2015 23:04, Mark Johnsen m...@ijohnsen.com ha scritto:

 Alex,

 Yes, the application is industrial grade, but it is quite simple (2 axes of
 motion).  I only need 1 modbus network to two temp controllers.  Since
 there are 2, that rules out '1' RS-232 network, but I can use '1' RS-485
 network.  Or Seb's USB setup would work.

 I did see on the mesa site the 7I34 8 channel RS-422/485 interface for
 Anything I/O.  I would think that would work.

 Your comment about industrial grade is my concern about using LinuxCNC at
 all.  I figure I can try it and if I run into issues I can slap in a brick
 PLC (omron, panasonic, etc) w/ some option cards, but that is much more
 expensive and less flexible in the long run.  I look at LinuxCNC w/ so much
 potential and it combines the control and HMI into one piece.  I realize it
 is not a traditional industrial control solution.  If you think I'm crazy
 for doing this, let me know now...


 

 SEB - I can embrace USB.  I just thought that was looked down upon due to
 the lack of real-time nature of USB ports?   Although, I don't really need
 real-time here for temp control.  Just updating and current temp feedback.

 I think for the price of the mesa board, that seems like a good option and
 more trustworthy than the Amazon USB part. Just my 2 cents..

 Thanks all for your feedback,
 Mark

 Hi Mark .
 Be careful with this kind of adapters because they are not optocoupled .
 If your application is an industrial grade I will spend some more money and
 buy something like the Advantech converter/adapter you linked above.
 Do you really need to have two separate Modbus network ?

 Alex

 --
 Dive into the World of Parallel Programming The Go Parallel Website,
 sponsored
 by Intel and developed in partnership with Slashdot Media, is your hub for
 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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Re: [Emc-users] Modbus RS-485 Connection with Mesa?