RE: mbbi/mbbo Mask values

["Dalesio, Leo" <dalesio@bnl.gov>]

In the record reference manual on the EPICS wiki
https://wiki-ext.aps.anl.gov/epics/index.php/RRM_3-14_Multi-Bit_Binary_Input
it states:

NOBT

Number of Bits

Number of hardware bits accessed. They must be consecutive.

It would be better if the introduction to this record type had pointed this out. I will chance that today - if I remember how to get into the wiki page.

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From: Dudley, David
Sent: Friday, June 01, 2012 8:42 AM
To: Dalesio, Leo; tech-talk@aps.anl.gov
Subject: Re: mbbi/mbbo Mask values

I am assuming that is defined somewhere?

Looking at the MBBI record definition, I see that Mask, ZRVl, ONVL, … FFVL are all ULONGS, which would allow a bit field to be defined that didn't depend on consecutive bits.  Seems that the limitation is that NOBT defines MASK.

If NOBT was set to 0 (I would take that meaning as "don't define mask"), seems MASK 'should' be able to be manipulated.

Looking in the ether-ip driver, it doesn't look like mask from the record is even used.  It builds it's own internally.

David

From: <Dalesio>, Leo <dalesio@bnl.gov>
Date: Friday, June 1, 2012 8:34 AM
To: David Dudley <ddudley@bnl.gov>, "tech-talk@aps.anl.gov" <tech-talk@aps.anl.gov>
Subject: RE: mbbi/mbbo Mask values

The limit/definition of the MBBx record types was that the bits were consecutive.
I think that you would have to use a calc record between the input and MBBx record to mask out the bits in between.
Bob