Experimental Physics and
Industrial Control System

[email protected] (Rozelle Wright) · Fri, 29 Mar 96 17:09:10 MST

> 
> > From [email protected] Fri Mar 29 10:50:35 1996
> > Return-Path: <[email protected]>
> > Date: Fri, 29 Mar 1996 17:48:19 +0000 (GMT)
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> > To: Epics Questions <[email protected]>
> > Subject: CALC record question
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> > 
> > Can anyone help me with the following:
> > 
> > I am trying to reset a value used in a calculation record
> > from a button on a 'dm' screen. The CALC field is set to
> > A+1 and the VAL field is looped back to INPA, so that continual
> > processing of the calculation record gives: 1, 2, 3, 4, etc.
> > 
> > I want a button on a 'dm' screen such that when it is pressed, the
> > above calculation starts again at 0. I thought this should be easy
> > but haven't managed it yet. 
> > 
> > I tried letting the button press put the
> > value 0 into INPB and changing CALC to B*{A+1} so that, 
> > normally B=1 and we have as before. When the button is
> > pressed, the record processes once with B=0 and then the
> > whole thing starts again. 
> > 
> > This doesn't work.
> > I suppose because the above means that INPB needs to take two 
> > inputs (the first, a hardwired 1, the second a 0 put into B when 
> > the button is pressed). 
> > In this case, how can the calculation record know which value it is 
> > supposed to be using? Or am I going about this in totally the wrong way?
> > 
> > Any help would be greatly appreciated?
> > 
> > Cheers,
> > 
> > Andy 
> > 
> > ===================================================================================
> > Andy Foster
> > Royal Greenwich Observatory	Tel:       44 (0)1223 374899 (direct)
> > Madingley Road			Fax:       44 (0)1223 374700
> > Cambridge			E-mail:    [email protected]
> > CB3 0HA				Home Page: http://www.ast.cam.ac.uk/~ajf
> > UK
> > 
> > 
> Hi Andy,
> This may work for you.  It does not require any new database records.
> 
> I am using edd/dm version 2.2.
> 
> My calculation record is called counter.
> and has the following properties.
> CALC: B?(B*(A+1)):0
> A: counter.VAL
> B: 1
> 
> I made a message button  to control counter.B.
> (titled RESET for both inactive and pressed)
> The press message is 0 and the release message is 1.
> 
> I hope this helps.
> Rozelle
> 
Something I didn't think about when I sent the first message.
If the calculation record is scanned periodically, the
reset button must be held down until the 0 value for B is seen.
Otherwise channel access will put the 1 value into B before the
record is processed and the zero will not be seen.
The reset will work immediately if the record is scanned passively.
Rozelle

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System