Experimental Physics and
Industrial Control System

Dirk Zimoch via Core-talk <core-talk at aps.anl.gov> · Thu, 12 Aug 2021 08:03:29 -0000

The change is in commit 04ff9eb "rec: mbbiDirect and mbboDirect refactoring" from 2012-12-12.
The documentation says: 
 * After the device support's init_record() routine returns during record
   initialization, if OMSL is supervisory and UDF is clear the fields
   B0-BF will be set from the current VAL field.
 * When a put to the OMSL field sets it to supervisory, the fields
   B0-BF will be set from the current VAL field. This did not used to happen,
   the individual bit fields were previously never modified by the record.
   Note that this change may require some databases to be modified, if they
   were designed to take advantage of the previous behavior.

This is exactly what happens. Thus this is no "bug". Also the behavior
is the same as before as long as OMSL is closed_loop, but that is not
the default.

What I would expect (but what is neither documented not implemented) is
that while OMSL is supervisory, one an write to the VAL field (which is
the "normal" behavior for output records) and that the record would
update the .Bx fields, This has never happened before but now only
happens when switching to supervisory bu not while OMLS is supervisory.

I will try to implement it...

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https://bugs.launchpad.net/bugs/1939568

Title:
  Writing to mbboDirect.VAL does not work any more in EPICS 7

Status in EPICS Base:
  New

Bug description:
  In EPICS 3.14, it was possible to write to mbboDirect.VAL. This does not work any longer with EPICS 3.15 or higher.
  However, writing to .VAL was always buggy anyway (did not update the.Bx fields).

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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System