Experimental Physics and
Industrial Control System

Mark Davis <[email protected]> · Wed, 1 Aug 2018 09:35:38 -0400

HI all,

I have run in to another problem with my attempts to control a stepper

motor using a Delta Tau controller.

Current configuration:

   Motor Controller:  Delta Tau Power Brick LV-IMS
   EPICS version:  3.14.12.2
   Asyn module:  4.32

   powerPMAC driver:  The 2014-09-25 version at

http://www.observatorysciences.co.uk/deltatau_downloads.php

   IOC config:

      #===== for Power Brick LV-IMS controllers =====

      drvAsynPowerPMACPortConfigure("SSH1", "192.168.137.234", "root",

"deltatau", "0", "0", "0")

      # 'Ctlr port name', 'SSH port name'. 'port address'. '#axes'

'Moving poll interval (ms)', 'Idle poll interval (ms)'

      powerPmacCreateController("PBRICK1", "SSH1", "0", "32", "25", "100")

      # open-loop axes (they don't use the encoder readback)
      pmacCreateAxis("PBRICK1", "3")

      asynSetTraceMask("PBRICK1", 0, 0)
      asynSetTraceMask("SSH1", -1, 0)
      asynSetTraceIOMask("SSH1", -1, 0)

      # includes a motor record...
      dbLoadTemplate("db/powerPMAC.substitutions")

Using this configuration, I can control the motor via the motor record

just fine, as long as I wait until the motor reaches the new position

after each new setpoint.

However, if I change the setpoint while the motor is still moving, it

will stop before getting to either the new or the previous setpoint, the

done moving bit in the status value from the controller stays at 0, and

new setpoints to the motor record are ignored.

If I then give the controller a move command directly, this works fine: 

The motor moves to the new position and the done moving bit goes back to

1, at which point new setpoints applied to the motor record will work again.

NOTE:  Changing the setpoint in a middle of the move using commands on

the controller itself also works fine (e.g. it will happily reverse

direction in the middle of a move to get to the latest setpoint).

Given how long the motor record has been around, I assume that such a

basic problem would have been resolved long ago.  And the controller is

fine with changes to the setpoint during a move, so I would think that

the problem must be in the driver.

Has anyone run in to this sort of thing before?  Someone mentioned that

the driver available from the Diamond Light Source incorporates the

driver I am using (i.e. it should work for Geo Brick and Power Brick

controllers?).  Does anyone now if this is a driver bug and whether or

not it is fixed in the DLS version?

Thanks.

--
Mark Davis
NSCL/FRIB
Control Systems Software Engineer
[email protected]

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System