Re: [foxboro] Ladder Logic
- From: tjvandew@xxxxxxxxx
- To: foxboro@xxxxxxxxxxxxx
- Date: Tue, 15 May 2012 13:21:18 +0000
Since the ladder logic is actually running in the FBM memory and not in the CP
I understand some of the limitations in terms of ladder size. It is a very
unique idea that other DCS vendors haven't attempted. It fills a small niche
but being able to use multiple FBM's in a virtual PLC processor is what would
be really useful.
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-----Original Message-----
From: Brian Long <blong@xxxxxxx>
Sender: foxboro-bounce@xxxxxxxxxxxxx
Date: Tue, 15 May 2012 06:52:11
To: <foxboro@xxxxxxxxxxxxx>
Reply-To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Ladder Logic
My original post was asking if anyone knew if Foxboro planned to improve
ladder. Your explanation below is one of the reasons we use it and why
with some minor improvements we could do away with brandX plc's and the
issues surrounding INT30's and / or FDSI's.
Thanks,
Brian
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of tjvandew@xxxxxxxxx
Sent: Tuesday, May 15, 2012 6:10 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Ladder Logic
Jeremy,
You are right about only being able to set an OFL from one rung and
about the size of the ladder, but we recompiled ladder logic routinely
with no bumps to the process. We considered that a strength compared to
recompiling HLBL sequence code where things could get squirrely. The
execution speed of the ladder was the other strength. CIN's and CO's are
processed in 3-5ms but bringing in IFL's or passing out to external
parameters like OFL's still happens at the PLB block processing cycle. If
you need first out functionality for CIN's connected to an FBM the PLB can
do it with a "trip trap". But if you need larger scale PLC capability
using a real PLC is still a better solution.
Cheers,
Tom
Sent from my Verizon Wireless BlackBerry
-----Original Message-----
From: Jeremy Milum <jmilum@xxxxxxxxx>
Sender: foxboro-bounce@xxxxxxxxxxxxx
Date: Mon, 14 May 2012 08:50:24
To: foxboro@xxxxxxxxxxxxx<foxboro@xxxxxxxxxxxxx>
Reply-To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] Ladder Logic
On Tuesday, May 1, 2012, DUNHAM, KENNETH J wrote:
> Curious to know what limitations you are referring to?
>
It's been a long time since I used PLBs, so I could be wrong on some of
these, but here is what I recall as some of the things that bothered me at
the time
* 100 rungs total per FBM
* only able to set a particular OFL from a single rung
* have to compile everything if editing a single rung, thus the process
must be down to make changes
--
--
Jeremy Milum
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_______________________________________________________________________
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Systems (formerly The Foxboro Company). Use the info you obtain here at
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