Experimental Physics and
Industrial Control System

Andy Foster <[email protected]> · Fri, 29 Mar 1996 17:48:19 +0000 (GMT)

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

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System