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

Subject: Re: MEDM display of string records not updating from PCASpy/PyEpics
From: Andrew Johnson <anj@aps.anl.gov>
To: <tech-talk@aps.anl.gov>
Date: Tue, 12 Sep 2017 13:47:25 -0500
Hi Keith,

What does camonitor show, on both the initial connection and when
there's an update?

Given that the display is correct when it first connects I suspect
there's something wrong either in pcaspy or in your python code; it
almost seems like the CA server is sending monitor update events of a
different data type to that which the client originally subscribed for.
I don't know if that's even possible through either pcaspy or pcas, but
it's the kind of thing that might cause the strange behaviour you're
reporting, and I wouldn't be too surprised if MEDM doesn't handle it well.

- Andrew


On 09/12/2017 01:34 PM, keith.thorne wrote:
> Dear Mark
> 
> The cainfo looks fine, with “Native data type: DBF_STRING” and “Request type: DBR_STRING”.  command-line caget comes backs with a string.
> 
> Of course, the MEDM text monitor says Format “decimal’.  I tried to use the MEDM editor to save it as “string" but see no change in the underlying *.adl file.  
> But according to the MEDM manual, it will always think it is a number, even for ‘string’.
> 
> These strings are typically longer than a numeric field (up to 40 characters), so I guess it puts out 00.00 as ‘exponential’ notation when there are too many characters?
> 
> So, what is the way to display string fields for a PV in MEDM? 
> 
> Thanks
> 	Keith
> 
>> On Sep 12, 2017, at 12:21 PM, Mark Rivers <rivers@cars.uchicago.edu> wrote:
>>
>> Hi Keith,
>>
>> Some questions:
>>
>> - What does command line cainfo say about that PV?
>> - What does command line caget show for that PV?
>> - In your medm display what "Format" have you selected for the text update widget, e.g. "decimal", "string", etc.?
>>
>> Mark
>>
>>
>> -----Original Message-----
>> From: tech-talk-bounces@aps.anl.gov [mailto:tech-talk-bounces@aps.anl.gov] On Behalf Of keith.thorne
>> Sent: Tuesday, September 12, 2017 11:52 AM
>> To: EPICS mailing list
>> Subject: MEDM display of string records not updating from PCASpy/PyEpics
>>
>> Dear all
>>
>> 	We have an odd behavior here with a continuously-running MEDM display.
>>
>> In most cases, where the EPICS IOC is running in C or similar, the MEDM displays of string variables happily update when the underlying PV is updated.
>>
>> However, we have a simple EPICS database that is done with PCASpy. We then use a pyEpics client to regularly update records in the EPICS database using pvPut().
>>
>> The updated numeric records all work fine.  However, the string records (when updated) appear as 00.00 or similar in the MEDM display.
>> If we open a new MEDM display, the correct value is shown.  If we slightly resize the MEDM display, it also updates.
>>
>> Any idea what is going on?
>> Is there something in the PCASpy database record fields we need to set to make this work?
>>
>> - Using command-line caput() we get updated values.
>>
>> — I was going to try an MEDM->caQtDM conversion to see if we get any different behavior.
>>
>> Thanks
>> 	Keith Thorne
>>
>> ------
>> Keith Thorne <kthorne@ligo-la.caltech.edu>
>> CDS Software Engineer
>> LIGO Livingston Laboratory
>> Livingston, LA 70754
>> Phone: (225)686-3168 Fax: (225)686-7189
>>
> 
> 
> 
> ------
> Keith Thorne <kthorne@ligo-la.caltech.edu>
> CDS Software Engineer
> LIGO Livingston Laboratory
> Livingston, LA 70754
> Phone: (225)686-3168 Fax: (225)686-7189
> 

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References:
MEDM display of string records not updating from PCASpy/PyEpics keith.thorne
RE: MEDM display of string records not updating from PCASpy/PyEpics Mark Rivers
Re: MEDM display of string records not updating from PCASpy/PyEpics keith.thorne

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