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<== Date ==> <== Thread ==>

Subject: Re: mbboDirect record initialization
From: Eric Norum <eric@norum.ca>
To: Rod Nussbaumer <bomr@triumf.ca>
Cc: "tech-talk@aps.anl.gov talk" <tech-talk@aps.anl.gov>
Date: Thu, 25 Oct 2012 11:44:09 -0700
Sorry to have sent this to the whole list -- please ignore.
On Oct 25, 2012, at 11:36 AM, Eric Norum <wenorum@lbl.gov> wrote:

> I think that the second-last sentence should read,  "initialize the input bits 'Bx' from VAL",  not, "from RVAL".
> 
> On Oct 25, 2012, at 11:26 AM, Rod Nussbaumer <bomr@triumf.ca> wrote:
> 
>> Hi all.
>> 
>> I'm using modbusAsyn with an mbboDirect record. At IOC init time, the
>> record correctly reads back from the modbus server (a Moxa Digital IO
>> box, but that doesn't seem relevant). This accomplishes initialization
>> of the .VAL field of the mbboDirect record, as expected. However, I
>> think that for this record type, the initialization should also be
>> applied to the input fields of the record. The basis for this is that
>> when the record subsequently processes due to a write/put to an input
>> field, the record will then re-compose the word to write on its OUT
>> link. Since the input bits will not have been initialized, they will go
>> out to the respective hardware bits as zeros, overwriting what was there
>> at startup.
>> 
>> I've already had a brief dialog with Eric Norum and mark rivers on this subject, and at least two possible courses have been mentioned. One is to initialize the mbboDirect at the record level, and another (which I've already tried quickly; seems to work) at the asyn level (devAsynUInt32Digital.c).
>> Is there anyone using this record type who thinks that changing the record behavior to initialize the input bits 'Bx' from RVAL would adversely affect their existing work? Any other records that may also benefit from changes?
>> 
>> Thanks.
>> 
>> Rod Nussbaumer
>> ISAC Controls, TRIUMF
>> Vancouver, Canada
> 
> -- 
> Eric Norum
> wenorum@lbl.gov
> 
> 

-- 
Eric Norum
eric@norum.ca






References:
mbboDirect record initialization Rod Nussbaumer
Re: mbboDirect record initialization Eric Norum

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