Experimental Physics and
Industrial Control System

haquin <[email protected]> · Tue, 30 Sep 2008 09:51:57 +0200

Hi all,
Here is what I do:

a Calcout record output its value into the VAL field of a Waveform
record (using a Process Passive link triggering the processing of the
Waveform).

Then the Waveform record performs a Modbus/TCP write access with
Asyn/Modbus device support.
My problem is the following:

Sometime though the last value is in the VAL field of the Waveform
record it is not written via Modbus.

I have already investigated on the Asyn/Modbus side, but it turns out
that when the problem occurs Asyn/Modbus is not even called.
It seems that the problem occurs when the Calcout record requests the
Waveform record for a new Modbus write access but the Waveform record is
still busy with the previous one...

Can someone explain me how to be warned or informed when the processing
request of a record is ignored because it is still busy (PACT=1).
I tried setting field TPROC=1 to check if the Waveform trace is missing
when the problem occur,

but this is intrusive and the problem is then not reproducible...
thanks.
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fn:Christophe Haquin
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Experimental Physics and Industrial Control System

Experimental Physics and
Industrial Control System