RE: Initializing starting position on a Motor

[Mark Rivers <rivers@cars.uchicago.edu>]

Are you using the EPICS autosave module to save your motor positions?  If so, then when you restart EPICS it should restore the previous position automatically.  The motor record actually does the following logic:

 

-          If the controller position at EPICS startup is non-zero it uses the controller position

-          If the controller position at EPICS startup is 0 it uses the autosaved position

 

What is causing the motor to move at the end of initialization?  That does not normally happen.

 

Mark

 

 

From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] On Behalf Of Tonia Batten
Sent: Tuesday, December 04, 2012 4:52 PM
To: tech-talk@aps.anl.gov
Subject: Initializing starting position on a Motor

 

Good Afternoon,

 

I am new to EPICS and am working on creating a motor controller for the PI E517 motor.  I am using EPICS R3.14.12 and Motor 6.5 I have got the device communicating and am able to perform the necessary commands but have run into a problem with initialization.  The problem is that when I restart my EPICS application I might be in the middle of a scan and therefore I don’t want the motor to change its current position (ideally I don’t want to have to move the motor to the same position).  At the moment when I restart the application the motor is returning to a zero position.   I suspect that I am not initializing the DVAL field correctly in the MOTOR record, but have not been able to confirm as the motor is moved as soon as the initialization is complete and before I can monitor.   Any feedback or direction would be greatly appreciated.

 

Regards,

Tonia Batten, P.Eng

Control System Analyst

Canadian Light Source

44 Innovation Blvd.

Saskatoon, SK S7N 2V3

Tel:  306-657-3865
Email: Tonia.Batten@lightsource.ca