Experimental Physics and
Industrial Control System

Ian Gillingham <[email protected]> · Wed, 10 Sep 2008 13:24:35 +0100

Using the EPICS motor record (for OMS MaxV) under R3.14.8.2, I am
experiencing some odd behaviour on IOC reboot and autosave.

I have some systems driving XY stages. The X axis behaves perfectly on
reboot (and restore), but the Y axis does not.
The observation is that, on IOC reboot, all Y axis motor record fields
'appear' to have restored correctly, but on driving the axis (in either
direction) the direction sense is inverted. The Y axis differs from the
X axis, in that the direction is inverted (due to gearing), so the motor
record is initialised with positive MRES, positive DIR, but negative ERES.

On setting UEIP to 'No', 'home' the axis, then set UEIP to 'Yes', the
direction sense is corrected an the axis behaves as expected.

My autosave files refer to the following motor record fields:
0.req:
DVAL OFF

1.req:
DIR DHLM DLLM TWV SREV MRES ERES RRES VBAS VELO ACCL BDST BVEL BACC RDBD
EGU RTRY UEIP URIP DLY PREC DISA DISP FOFF OFF FRAC OMSL JVEL JAR

The startup script makes the following calls before iocInit():
set_pass0_restoreFile("0.sav")
set_pass0_restoreFile("1.sav")
set_pass1_restoreFile("1.sav")

Motor parameters:
MRES: 0.00005
UREV: 0.01
ERES: -0.00002
DIR:  'Pos'

I have tried issuing the DBI command (to invert the output direction at
the MaxV card), whilst setting DIR to 'Neg', but this swaps the
associated limit switches! So, not a solution.

Is anyone aware of known issues in this area? I seem to recall something
about negative ERES values being mentioned in the past, but unable to
find any references.

Ian Gillingham
Diamond Light Source

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System