EPICS Re: mbbi/mbbo Mask values

Experimental Physics and Industrial Control System

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Subject:	Re: mbbi/mbbo Mask values
From:	"Dudley, David" <[email protected]>
To:	Ralph Lange <[email protected]>, EPICS Tech Talk <[email protected]>
Date:	Fri, 1 Jun 2012 17:32:50 +0000

That actually was my initial consideration, but didn't want to consider
the possibility that for some odd reason, something, somewhere might
depend on NOBT being 0.

The driver I'm using already builds it's own mask, and doesn't look at or
use the record's mask, it just needed 2 lines modified to allow you to
specify the mask as part of the input/output specification.  The NOBT
field is now able to be set for the number of consecutive bits to be
retrieved, and the driver mask tells the driver which bits in that range
actually mean something.

Seemed like a reasonable idea, to me.

David

On 6/1/12 12:35 PM, "Ralph Lange" <[email protected]> wrote:

>On 01.06.2012 18:02, Andrew Johnson wrote:
>> Hi Bob,
>>
>> On 2012-06-01 Dalesio, Leo wrote:
>>> The wiki page now clearly states in the introduction to the MBBI and
>>>MBBO
>>>  that the bits must be continuous.
>> My point was that the record code doesn't need the bits to be
>>contiguous; it 
>> will still work properly as long as the result of (RVAL << SHFT)
>>matches one 
>> of the xxVL field values.  I have no intention of letting anyone change
>>the 
>> code to break that since there are too many device supports and IOCs
>>out there 
>> which could be relying on this.
>
>What about allowing MASK to be set in the database, and only setting it
>in the init_record() code, if it is 0.
>That would not break existing code (or would it?), and provide an easy
>way to set MASK directly (contiguous or not), avoiding NOBT and SHFT.
>
>~Ralph
>

References:: Re: mbbi/mbbo Mask values Ralph Lange

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