Re: [foxboro] peer 2 peer loop strategy conclusion
- From: "foxpat" <foxpat@xxxxxxxxxxxxx>
- To: <foxboro@xxxxxxxxxxxxx>
- Date: Mon, 2 Apr 2012 20:45:02 +0200
Ajit,
We have similar situations and prefer the P2P approach (unless I/O can be
easily re-arranged so it will all fit in the same CP) but not without
special 'shedding' logic (typically routing the signals through a CALC)
which detects P2P failures and takes proper measures whenever P2P should
fail.
These measures typically involve 'breaking the loop' at the highest possible
level (keep as much as possible in automatic control). This could mean that
the complete complex control loop could end up completely in manual, which
in most cases, is a stable situation and can prevent process upsets. It also
allows controlled 'recuperation' of a failed P2P (signals might have an
unexpected value after CP restores to normal operation!)
Using a CALC.RIxx also allows 'optimizing' the change-delta involved in P2P
communications.
Freezing the signal is an option but most of the time is not sufficient or
even dangerous; example; freeze the fuel flow might lead to a fully open
fuel valve if the controller is left in AUTO.
I am not sure if I understood your actual fault correctly; did CP1
completely fail or only the FBM04 (with the AOUT)?
Kind regards,
Patrick Martens
-----Oorspronkelijk bericht-----
Van: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
Namens Ajit.S.Kumar@xxxxxxxxxxxxx
Verzonden: zondag 1 april 2012 22:43
Aan: 'foxboro@xxxxxxxxxxxxx'
Onderwerp: [foxboro] peer 2 peer loop strategy conclusion
Dear All,
Suggestions required, Thanks in advance.
What are the advantages/disadvantages of P2P communication in an complex
loop.
We have few control loop hardwired between FBM's due to complicity but need
to find a better way to avoid FBM failures or Open wires which drives the
complex loops to plant upset.
Is P2P a better industrial way in the Refinery Applications. The present
scenario is to convert the FBM to redundant type, but still we need a better
answer to use P2P.
Thanks and best regards
A.kumar
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