5i20 configure for step/dir + encoder
27 Jul 2010 18:34 #3497
by aike
5i20 configure for step/dir + encoder was created by aike
Hi!
I need to configure 5i20 card. I have servo with step/dir pulses, but at the same time I have
3 signal (A,B,Z) from this drive.
I used pncconf. Configure 2 encoders (lathe), 2 step generators. But pncconf tell me "You foget assign pwm for X,Z".
What I need to do?
I need to configure 5i20 card. I have servo with step/dir pulses, but at the same time I have
3 signal (A,B,Z) from this drive.
I used pncconf. Configure 2 encoders (lathe), 2 step generators. But pncconf tell me "You foget assign pwm for X,Z".
What I need to do?
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27 Jul 2010 19:16 #3499
by andypugh
Replied by andypugh on topic Re:5i20 configure for step/dir + encoder
This is probably a question best asked in the new Pncconf section of the forums.
However, I would be tempted to create some dummy pwms and then hand-edit the HAL to remove them again.
You want whatever is linked to the PWM inputs to connect instead to the stepgen inputs.
However, I would be tempted to create some dummy pwms and then hand-edit the HAL to remove them again.
You want whatever is linked to the PWM inputs to connect instead to the stepgen inputs.
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28 Jul 2010 06:03 #3503
by cmorley
Replied by cmorley on topic Re:5i20 configure for step/dir + encoder
You are confusing pncconf by asking for stepgens with encoders for each axes.
encoder feedback with steppers is not supported out of the box.
assign a custom name for the encoders (such as "x-feedback" don't use spaces) and configure / connect them in the custom HAL file.
not sure if your looking just to be able to read the feedback or use it to stop on following error or even try to correct following error.
encoder feedback with steppers is not supported out of the box.
assign a custom name for the encoders (such as "x-feedback" don't use spaces) and configure / connect them in the custom HAL file.
not sure if your looking just to be able to read the feedback or use it to stop on following error or even try to correct following error.
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28 Jul 2010 09:41 #3507
by andypugh
Replied by andypugh on topic Re:5i20 configure for step/dir + encoder
cmorley wrote:
It possibly ought to be, as step-direction servo drives are not all that uncommon (even if they do put the control loop a little further from EMC2s control than is really ideal)
You are confusing pncconf by asking for stepgens with encoders for each axes.
encoder feedback with steppers is not supported out of the box.
It possibly ought to be, as step-direction servo drives are not all that uncommon (even if they do put the control loop a little further from EMC2s control than is really ideal)
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29 Jul 2010 01:37 #3513
by cmorley
Replied by cmorley on topic Re:5i20 configure for step/dir + encoder
I have not heard of anyone running steppers (or step/direction servos) with encoder feedback that was used in a PID loop.
I do see in another thread someone is trying...
One guy monitored the feedback and got EMC to throw an E-stop if following error got to big. (this was through parallel port) .
If someone can show me a working config and it does not cause me too much trouble to add it -I will.
Personally I don't really see the idea.
If you want ease of setup use step / direction drives.
if you want ultimate control use servos with feedback to EMC's PID
Other then doing it just to see if it works.....
To each their own.
I do see in another thread someone is trying...
One guy monitored the feedback and got EMC to throw an E-stop if following error got to big. (this was through parallel port) .
If someone can show me a working config and it does not cause me too much trouble to add it -I will.
Personally I don't really see the idea.
If you want ease of setup use step / direction drives.
if you want ultimate control use servos with feedback to EMC's PID
Other then doing it just to see if it works.....
To each their own.
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29 Jul 2010 10:12 #3516
by andypugh
Replied by andypugh on topic Re:5i20 configure for step/dir + encoder
cmorley wrote:
I assume that you could use a step-dir servo drive with a PID loop fairly readily. You would be asking for changes in position rather than velocity to close the loop, but I see no reason why it couldn't be made to work. In effect absolute position and homing would be handled by EMC2 PID with loop stability handled by drive PID.
There may be velocity-mode drives with up-down inputs too, where it would make sense to use a particular stepgen mode as the output function.
Stepgens are also usable as the output function for a frequency-voltage external stage, which I have seen suggested but don't know if it is often used. (freqgen is floating point so might not always be preferred).
Not that the possible existence of a particular setup justifies adding it to a tool like pncconf. I think it is perfectly reasonable to expect "unusual" configurations to be hand-coded in HAL. It makes no sense for you to spend a week saving one user an hour.
I think that people have used stepper motors in velocity mode with an encoder for closed-loop control, but I am not sure how well it has worked.I have not heard of anyone running steppers (or step/direction servos) with encoder feedback that was used in a PID loop.
I assume that you could use a step-dir servo drive with a PID loop fairly readily. You would be asking for changes in position rather than velocity to close the loop, but I see no reason why it couldn't be made to work. In effect absolute position and homing would be handled by EMC2 PID with loop stability handled by drive PID.
There may be velocity-mode drives with up-down inputs too, where it would make sense to use a particular stepgen mode as the output function.
Stepgens are also usable as the output function for a frequency-voltage external stage, which I have seen suggested but don't know if it is often used. (freqgen is floating point so might not always be preferred).
Not that the possible existence of a particular setup justifies adding it to a tool like pncconf. I think it is perfectly reasonable to expect "unusual" configurations to be hand-coded in HAL. It makes no sense for you to spend a week saving one user an hour.
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30 Jul 2010 02:23 #3522
by cmorley
Replied by cmorley on topic Re:5i20 configure for step/dir + encoder
andypugh wrote:
I should have added "in EMC" I know for instance Parker S6 step drives can use encoder feed back. With Parker the resolution of the encoder was supposed to be 3 times the step resolution. or was it the other way? I assume to help stop hunting.
cmorley wrote:
I think that people have used stepper motors in velocity mode with an encoder for closed-loop control, but I am not sure how well it has worked.I have not heard of anyone running steppers (or step/direction servos) with encoder feedback that was used in a PID loop.
I should have added "in EMC" I know for instance Parker S6 step drives can use encoder feed back. With Parker the resolution of the encoder was supposed to be 3 times the step resolution. or was it the other way? I assume to help stop hunting.
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30 Mar 2011 05:24 #8273
by Zig
Replied by Zig on topic Re:5i20 configure for step/dir + encoder
There is always an exception to the rule.
I am runing a gantry mill based on
Anaheim Automation BLDC
Renishaw linear scales
CNCTeknix ( the Australian manufacturer ) Tek 6 STEP/DIRECTION servo amps.
Tek 6 provides for a simple control input ( stepper motor like) and at the same time it reads the quadrature encoder to drive the servo motor in a closed loop.
As with any steper motor like drive the software does not know whether the servo is performing correctly. To eliminate this ambiguity I would like to feed the encoder signals back to EMC.
Tek 6 does retransmit the encoder signals so that a simple digital interface is possible .
pncconfig looked promising until it said NO to stepers and encoders. Any kind of help or hints would be welcome.
I am presently looking to stepgen.9 as a source of step direction pulses with the PWM value from servo drive pin as input.
Someone please tell me not to bother and try a smarter idea or better still that pncconfig is coming out with a revamped capability.
I am runing a gantry mill based on
Anaheim Automation BLDC
Renishaw linear scales
CNCTeknix ( the Australian manufacturer ) Tek 6 STEP/DIRECTION servo amps.
Tek 6 provides for a simple control input ( stepper motor like) and at the same time it reads the quadrature encoder to drive the servo motor in a closed loop.
As with any steper motor like drive the software does not know whether the servo is performing correctly. To eliminate this ambiguity I would like to feed the encoder signals back to EMC.
Tek 6 does retransmit the encoder signals so that a simple digital interface is possible .
pncconfig looked promising until it said NO to stepers and encoders. Any kind of help or hints would be welcome.
I am presently looking to stepgen.9 as a source of step direction pulses with the PWM value from servo drive pin as input.
Someone please tell me not to bother and try a smarter idea or better still that pncconfig is coming out with a revamped capability.
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30 Mar 2011 07:05 #8276
by cmorley
Replied by cmorley on topic Re:5i20 configure for step/dir + encoder
here is how one user did it:
www.linuxcnc.org/component/option,com_ku...7/lang,english/#5489
www.linuxcnc.org/component/option,com_ku...7/lang,english/#5489
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30 Mar 2011 10:25 #8279
by andypugh
Replied by andypugh on topic Re:5i20 configure for step/dir + encoder
You can probably set up your system to use velocity-mode step generators and a PID loop.
Create a generic servo config, but then combine it with your existing stepper config so that the PID output goes to the stepgen velocity input, rather than the PWM input.
Alternatively, do those drives have the option of taking an analogue or PWM input?
Create a generic servo config, but then combine it with your existing stepper config so that the PID output goes to the stepgen velocity input, rather than the PWM input.
Alternatively, do those drives have the option of taking an analogue or PWM input?
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