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<== Date ==> <== Thread ==>
Subject: Re: mbboDirect Bx fields don't update on alarm change
From: Andrew Johnson via Tech-talk <tech-talk at aps.anl.gov>
To: Sue Witherspoon <withers at jlab.org>, "tech-talk at aps.anl.gov" <tech-talk at aps.anl.gov>
Date: Fri, 16 Sep 2022 14:19:09 -0500
Hi Sue,

On 9/15/22 6:34 PM, Sue Witherspoon via Tech-talk wrote:
     Was there ever a 'fix' for this?  I have a very simply db  where a mbboDirect feeds and AO record. The AO record writes to HW. During normal
operations the Bits are toggled on/off and that works. But during a maintenance period the engineers want to enter an integer value.  This does
not work anymore. It worked in 3.14 but now in 3.15 it doesn't.

I believe this is related to what Andrew was describing: https://epics.anl.gov/tech-talk/2021/msg01619.php
Did the Epics experts every resolve this?
I suspect this 2012 commit to the 3.15 branch caused the breakage that you are seeing (mea culpa, sorry!), but I haven't looked at it in detail to confirm that.

There were commits made to the mbboDirect record on the 7.0 branch in September-October 2021 after the above tech-talk conversation. The release notes for EPICS 7.0.6.1 said:

mbboDirectRecord enhancements

The bit fields B0 - B1F of this record are now always updated and have a monitor posted when the VAL field is set and the record processed. It is now possible to initialize the record's value by setting the bit fields inside a database file as long as no other method was used to initialize it (suc as setting VAL directly, using DOL, or by an initial readback from device support). A new internal field OBIT was added to store information about monitors posted on the bit fields.


However we have not made any similar changes to the record type on the 3.15 branch, and I don't think the core developers would have time to do so, although we would probably accept and merge a pull request for a back-port of those changes from the 7.0 branch to 3.15 for sites that can't upgrade to EPICS 7.

This is the behavior I'm seeing from an IOC running EPICS 7.0.6.1, which matches your 3.14.11 results:
tux% caget MbboRec.VAL
MbboRec.VAL                    0
tux% caput MbboRec.VAL 2048
Old : MbboRec.VAL                    0
New : MbboRec.VAL                    2048
tux% caput MbboRec.BB 0
Old : MbboRec.BB                     1
New : MbboRec.BB                     0
tux% caput MbboRec.BC 1
Old : MbboRec.BC                     0
New : MbboRec.BC                     1
tux% caget MbboRec.VAL
MbboRec.VAL                    4096

We haven't made a release from the 3.15 branch for about a year now and one is due, so back-porting this fix would give us a reason to do that.

HTH,

- Andrew
-- 
Complexity is free, it's Simplicity that takes work.
References:
Re: mbboDirect Bx fields don't update on alarm change Sue Witherspoon via Tech-talk
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