Pat -
I am doing something similar to what you are doing but here are the linkages
that are used (by the way, this was programmed by FoxMass). It seems to work
just fine from what I have seen.
Assume the PID block name = PID, first analog valve name PV1, other valve
PV2 etc.
PID.BCALCI :PID.OUT
PID.FBK :PID.OUT
PID.INITI (NO CONNECTION)
CHARC1.BCALCI :PV1.BCALCO
CHARC2.BCALCI :PV2.BCALCO
PV1.MEAS :CHARC1.OUT
PV2.MEAS :CHARC2.OUT
Hope this helps.
Thanks-
Marci Sewell
Dow Corning Corporation
Process Automation and Control
115 Bldg, Mail 032
ph: (517)496-5071 page: (517)926-1487
email: [EMAIL PROTECTED]
-----Original Message-----
From: O'Brien, Con (EUPRO) [mailto:O'[EMAIL PROTECTED]]
Sent: Thursday, March 23, 2000 6:10 PM
To: 'Foxboro DCS mail list'
Subject: PRIBLK - Our special friend
Good morning everyone!
After reading the postings of the last couple of days, I feel emboldened to
share some of my troubles with you all.
I'm trying to pass the "PRIBLK" initialization request and acknowledgment
bits between one controller and two output blocks. The application is a
split-range controller, with the PID output going through two CHARC blocks
to two AOUT blocks. I'm calculating the BCACLI input for the PID block
explicitly in a CALC block, using the BCALOs from the CHARC blocks.
This is straightforward enough, and normally I would do without the PRIBLK
functionality, because all blocks are running in one compound, at the same
period and phase. But unfortunately, the CHARC doesn't seem to recalculate
it's BCALCO unless PRIBLK is set.
I've come up with a way around, using dummy BIAS blocks to terminate the
initialization chains, but I would really like to be able to pass the BCALC
status bits from both CHARC blocks through to the PID.
Does anyone have a way of explicitly handling the initialization and
acknowledgment bits in a CALC block?
Many thanks,
Con O'Brien
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