Experimental Physics and
Industrial Control System

Kevin Peterson via Tech-talk <tech-talk at aps.anl.gov> · Fri, 19 Jan 2024 08:53:50 -0600

Mark,

It seems like the command sent in the GalilAxis::setEncoderPosition

method might be failing:

https://github.com/motorapp/Galil-3-0/blob/eb8b8c32c481374f34656faf3bca0df48e7a39c8/3-6/GalilSup/src/GalilAxis.cpp#L1354

The status from the sync_writeReadController() call is saved and returned:

https://github.com/motorapp/Galil-3-0/blob/eb8b8c32c481374f34656faf3bca0df48e7a39c8/3-6/GalilSup/src/GalilAxis.cpp#L1358

But the setPosition method returns asynSuccess unconditionally, so the

IOC wouldn't know if setting the encoder position failed.

It doesn't look like asyn traces would be very helpful;

sync_writeReadController doesn't appear to print anything when errors occur:

https://github.com/motorapp/Galil-3-0/blob/eb8b8c32c481374f34656faf3bca0df48e7a39c8/3-6/GalilSup/src/GalilController.cpp#L5470-L5563

Can you use a debugger or add an asyn trace message to see what the

setEncoderPosition return value is?

Kevin

On 1/18/24 18:28, Mark Rivers via Tech-talk wrote:

Folks,

I am having 2 serious issues with using “set” mode in the motor record

to set the current motor position on a Galil controller.

  * It works fine to set the position when the motor is not using an
    encoder and when not at a hard limit.  Setting the position sets
    both the drive values (VAL, DVAL, RVAL) and the readback values
    (RBV, DRBV, RRBV).
  * When setting the position of a motor with an encoder the VAL, DVAL,

 and RVAL are set correctly.  However, the readbacks are not set.

 This means that subsequent moves are not correct, because they act

    as if the motor is currently at the readback position, and move by
    the wrong amount.  I have attached a screenshot (Set_to_0_at_1.png)
    showing a motor that had been at DVAL=1, and then I set it to
    DVAL=0.  Note that the readbacks are still for DVAL=1.
  * If the motor has an encoder and is at a hard limit when I set the
    position then the result is that RVAL gets set to -2^31.  The system
    is totally unusable, because it now thinks the motor is outside the
    soft limits.  This is shown in screen shot
    Set_to_0_at_-10_on_limit.jpg.  The motor was on a limit with a DVAL

 of about -10.7.  I set the position to 0, and now the DVAL is -107374.

Note that driving to a limit and then setting the position is a common

operation, because we know what the absolute position of the limit

switch is.  But this does not work at all with the Galil.

Have others seen these problems?  Am I doing something wrong?

Thanks,

Mark

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System