Re: [foxboro] IND question
- From: "Johnson, Alex P (IOM)" <Alex.Johnson@xxxxxxxxxxxx>
- To: "foxboro@xxxxxxxxxxxxx" <foxboro@xxxxxxxxxxxxx>
- Date: Mon, 1 Mar 2010 13:07:25 -0600
Re: External references to blocks in the same CP
If the external reference (:C:B.P or ::B.P) in sequence code references a CBP
in the same CP the block does not suspend, but it does slow down. Each external
reference takes "roughly" the same amount of time as a AIN block or line so
HLBL code.
In general, the slow down should be milliseconds and of not much import for
most applications.
Regards,
Alex Johnson
Invensys Operations Management
10900 Equity Drive
Houston, TX 77041
+1 713 329 8472 (desk)
+1 713 329 1600 (operator)
+1 713 329 1944 (SSC Fax)
+1 713 329 1700 (Central Fax)
alex.johnson@xxxxxxxxxxxx (current)
alex.johnson@xxxxxxxxxxxxxxxx (good until September 2010)
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On
Behalf Of Corey R Clingo
Sent: Monday, March 01, 2010 11:21 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] IND question
"Part of the issue is the external references - assuming it is outside the
CP holding the IND block.
If that is the case, each one of those will suspend the block for 1 BPC
(minimum) which translates into 1 block period."
Alex,
If the external references are in the same CP, or compound, does this
still hold? Could you make connections to AIN blocks or whatever and then
reference those in the HLBL without the time penalty?
Corey
"Johnson, Alex P (IOM)" <Alex.Johnson@xxxxxxxxxxxx>
Sent by: foxboro-bounce@xxxxxxxxxxxxx
03/01/2010 08:58 AM
Please respond to
foxboro@xxxxxxxxxxxxx
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Subject
Re: [foxboro] IND question
Part of the issue is the external references - assuming it is outside the
CP holding the IND block.
If that is the case, each one of those will suspend the block for 1 BPC
(minimum) which translates into 1 block period.
So, at the minimum, your WAIT UNTIL is adding 1 block period delay.
Can you bring that value into a RIxxxx parameter? That would eliminate
that delay. The same hold true for the external references in the rest of
the code.
I once had a client call and complain that his safety shutdown logic took
to long to run. I asked how is it implemented and how long does it take.
He said it is 20 lines of sequence code and it takes 10s to complete. He
sent the code with his reply. It was 20 external references in a block
with a 0.5 PERIOD. I had to explain that what he saw is normal.
The fix? Bring the values in as connections.
Does this help?
Regards,
Alex Johnson
Invensys Operations Management
10900 Equity Drive
Houston, TX 77041
+1 713 329 8472 (desk)
+1 713 329 1600 (operator)
+1 713 329 1944 (SSC Fax)
+1 713 329 1700 (Central Fax)
alex.johnson@xxxxxxxxxxxx (current)
alex.johnson@xxxxxxxxxxxxxxxx (good until September 2010)
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