Experimental Physics and
Industrial Control System

[email protected] · Wed, 24 Apr 2002 08:33:17 -0500

Another thought related to this topic.

The EPICS "motor" record currently uses the "Reject" model if a request is
made to move past a soft limit.  However, it does set a field, .LVIO (Limit
Violation) if a move request is made that would violate the soft limits
(.LLM, .HLM), so there is an "alarm" visible on operator interfaces (but I
think it does not really raise alarms, those are set by checking against the
standard .LOW, .HIGH, etc. fields).  Generally I think that "Reject" is the
desired behavior, because the invalid request is likely due to operator
error.  

However, just last week I had to modify the SNL program for our
monochromator in order to implement the "Clamp" behavior, moving to the soft
limit if the calculated position for a motor was beyond the soft limit.  It
would also be nice if the motor record could be switched between the two
modes (Reject or Clamp) that are being discussed for the ao record.  My
point is that this is a more general problem than "ao" and it would be nice
to agree to a solution that can be slowly propogated to other records.

Mark Rivers

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System