Experimental Physics and
Industrial Control System

"[email protected]" <[email protected]> · Wed, 1 Aug 2018 16:04:54 +0000

Hi Mark,

See latest pmac at https://github.com/dls-controls/pmac/releases/tag/2-1

I agree with Mark R that this is related to an interaction between driver and NTM but I don't think a well behaved driver should ever exhibit what you describe.

________________________________
From: [email protected] <[email protected]> on behalf of Mark Rivers <[email protected]>
Sent: 01 August 2018 15:21:19
To: [email protected]; Mark Davis
Subject: Re: Delta Tau motor control problem

Hi Mark,

The motor record contains an NTM field that controls the behavior when a new target value is entered and the motor is still moving.  What value does NTM have for your record?

Mark

________________________________
From: [email protected] <[email protected]> on behalf of Mark Davis <[email protected]>
Sent: Wednesday, August 1, 2018 8:35 AM
To: [email protected]
Subject: Delta Tau motor control problem

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]

-- 
This e-mail and any attachments may contain confidential, copyright and or privileged material, and are for the use of the intended addressee only. If you are not the intended addressee or an authorised recipient of the addressee please notify us of receipt by returning the e-mail and do not use, copy, retain, distribute or disclose the information in or attached to the e-mail.
Any opinions expressed within this e-mail are those of the individual and not necessarily of Diamond Light Source Ltd. 
Diamond Light Source Ltd. cannot guarantee that this e-mail or any attachments are free from viruses and we cannot accept liability for any damage which you may sustain as a result of software viruses which may be transmitted in or with the message.
Diamond Light Source Limited (company no. 4375679). Registered in England and Wales with its registered office at Diamond House, Harwell Science and Innovation Campus, Didcot, Oxfordshire, OX11 0DE, United Kingdom

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System