Experimental Physics and
Industrial Control System

Emmanuel Mayssat <[email protected]> · Thu, 17 Mar 2005 10:23:35 -0800

Additional info:
In my specific case, the signal to process is a diagnostic signal.

So it doesn't need to be read permanently. Let's say once every 30 sec,
I process the input. Actually I was thinking about having another record
to turn on or off the record processing.
I have 40 of those inputs.
A hardware solution would definitely be better, but because of space,
cost, and time considerations it was decided that I, the software
programmer, would take care of it.
--
E
Ned Arnold wrote:

Two suggestions ...
1) Since you are looking for a transition, choose a TTL input module
whose inputs can be configured to generate an interrupt on a
transistion, have this interrupt process a calc record that simply
increments, and have another calc record that makes sure the first calc
record increments at least 100 times over a second (or 10 times every .1
second).
2) OR, add a little FPGA circuit (or a timer relay) that expects a
transition every 10 milliseconds (a simple watchdog) and use this output
to drive the digital input. This is preferred because it eliminates
100Hz processing of records.

 Ned

Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System