What motor controller and driver software are you using?
The motor record attempts to read the hardware position at reboot. If the controller value is non-zero then it assumes the position is valid, and it will use it. That value will take precedence even over an autosaved value.
When you reboot should your controller still have a valid readback reading, or does it become undefined?
From: firstname.lastname@example.org [email@example.com] on behalf of Peter Linardakis [firstname.lastname@example.org]
Sent: Monday, October 21, 2013 9:55 PM
Subject: Proper initialisation of Motor Record .RMP value
We're pretty new at controlling motors using EPICS and we've run into a few small issues. After a crate reboot, some of a bank of 28 motors end up with a motor.RMP value that is quite close to the signed 32-bit integer limit (both at max and min ends). If we then try move the motor more than the difference, the motor just stops. We're not running a complicated setup, we just home the motors using limit switches. We do not use encoders at this time.
My question is, how do we properly initialise the .RMP value to some known value, probably zero? At this stage of the game, we're not looking to use an autosave module or similar.
Dr Peter Linardakis
Accelerator Research and Development Engineer
Nuclear Physics | Research School of Physics and Engineering
Australian National University
p: (02) 6125 2862 f: (02) 6215 0748