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<== Date ==> | <== Thread ==> |
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Subject: | RE: Substituting every period scan in EPICS MODBUS by I/O Interrupt |
From: | Mark Rivers via Tech-talk <tech-talk at aps.anl.gov> |
To: | "Marco A. Barra Montevechi Filho" <marco.filho at lnls.br> |
Cc: | tech-talk <tech-talk at aps.anl.gov> |
Date: | Mon, 25 Jul 2022 22:20:47 +0000 |
Ø
Does this mean that, whatever the modbus device is that i am communicating, i can always substitute my 'field(SCAN, "1 Second")' to 'field(SCAN, "I/O Intr")' and go out unpunished?
Yes, that is true. This assumes that you are not using the “absolute” addressing option, because in that case there is no poller thread. When you are not using absolute addressing then the poller thread is constantly reading a block of
Modbus registers. If your record has SCAN=1 second, for example, then it calls the driver and retrieves the most recent poll value. It does not cause a Modbus transaction to occur. If you use SCAN=I/O Intr then your record will only process when the driver
finds that the value has changed. This will be much more efficient for bits and registers that rarely change state. Ø
Will this work against me in the future? No, it is the recommended way to run. Mark From: Tech-talk <tech-talk-bounces at aps.anl.gov>
On Behalf Of Marco A. Barra Montevechi Filho via Tech-talk Good evening for all. I was reading the
EPICS MODBUS documentation after realising that i had misspelled a SCAN field in my modbus application and came across the following: Aviso Legal: Esta mensagem e seus anexos podem conter informações confidenciais e/ou de uso restrito. Observe atentamente seu conteúdo e considere eventual consulta ao remetente antes
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