Folks,
I figured out the problem. The issue was that the Galil driver uses the
EncoderRatio that is sent to it by devMotorAsyn.c during iocInit. The
encoder ratio is calculated as EncoderRatio=MRES/ERES, i.e. the motor
resolution divided by the encoder resolution. My issue was that the
encoder resolution was not yet defined at iocInit, because it was not
defined in a database or autosave file. It was thus 0, and the encoder
ratio was infinite. That problem is invisible to the user, because
later ERES is computed by the motor record, and so it appears OK in OPI
screens. I fixed the problem by defining MRES in my motor template file.
devMotorAsyn should be fixed so that if ERES=0 it sets EncoderRatio to
1, not to infinite. That is the normal case, and would have avoided
this issue.
Thanks,
Mark
*From:*Pearson, Matthew <pearsonmr at ornl.gov>
*Sent:* Friday, January 19, 2024 11:32 AM
*To:* Mark Rivers <rivers at cars.uchicago.edu>; tech-talk at aps.anl.gov
*Subject:* RE: Problems setting motor position on Galil controller
Hi Mark,
I’ve not seen this before, and we do that all the time (but only ever
with stepper motors).
You could try setting the Galil commands manually via Galil GDK/Tools,
to figure out if it’s an issue with the driver or the Galil firmware.
You could also check the Galil DMC log file (if you have that configured
in the IOC) to see exactly the commands being sent to the controller. It
should be DP and DE to set the positions, but the order of those two
commands is inverted for servo type motors and I’m not sure why.
Cheers,
Matt
*From:*Tech-talk <tech-talk-bounces at aps.anl.gov
<mailto:tech-talk-bounces at aps.anl.gov>> *On Behalf Of *Mark Rivers via
Tech-talk
*Sent:* Thursday, January 18, 2024 7:28 PM
*To:* tech-talk at aps.anl.gov <mailto:tech-talk at aps.anl.gov>
*Subject:* [EXTERNAL] Problems setting motor position on Galil controller
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
