Re: [foxboro] One Mesh vs Multimesh
- From: "Easley, Jack" <Jack.Easley@xxxxxxxxxxxx>
- To: "foxboro@xxxxxxxxxxxxx" <foxboro@xxxxxxxxxxxxx>
- Date: Wed, 10 Nov 2010 19:01:50 -0600
Thanks Gaylon,
We have also had very rare hot-remarries of fault-tolerant ZCP270s, but no
worse than the old CP30/40s and no control fatalities involved. Just wanted to
make sure we weren't missing something bigger that was lurking...
Jack Easley
Sr. I&C Technician
Luminant Power, Martin Lake Plant
Phone 903.836.6290
jack.easley@xxxxxxxxxxxx
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx] On
Behalf Of Hicks, Gaylon F
Sent: Wednesday, November 10, 2010 6:35 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] One Mesh vs Multimesh
Hi Jack,
Wow, that bill collector crack perked everyone up. Now for some
background.
We haven't had a unit trip or transient due to the ZCPs, but we have had
a few issues with single switches rebooting, and a couple of years ago
had an issue with all the I/O on the ZCPs occasionally and randomly
going BAD for one cycle during the seven day hot remarry, which caused
control loops to quietly fail to manual. We have fixed that by
installing new ZCP images, and adjusting some timeout parameters which
we had set much to tightly, but we are still getting some strange FCM
messages occasionally on the seven day hot remarry.
We've also spent a lot of time setting up our mesh switches, including
using VLANs to segregate each ZCP field bus from the mesh, and the more
I deal with the switches the more attractive the FCP dedicated field bus
looks. Even the high end N1/N3/N7 blade switches are still a commercial
network product, and (although we are in this boat now), entrusting my
I/O to these switches doesn't give me a warm fuzzy feeling. In my
highly paranoid state, I can easily imagine a lot of scenarios where we
go to work on a failed switch, and somehow Do Something Bad to the other
switch or network. Doing Something Bad typically never ends well.
We initially went with the ZCPs in 2005 because we had more than four
base plates on several CPs, and had no choice. We have been using FCPs
in applications since, and I plan on changing the ZCPs to FCPs/FEMs in
the future, just to get rid of the potentially nasty failure modes
associated with the switch failures. The FCPs are just so much easier
to deal with all around.
Thanks,
Gaylon Hicks
TVA - Browns Ferry
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Easley, Jack
Sent: Wednesday, November 10, 2010 3:46 PM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] One Mesh vs Multimesh
Just wondering what issues you've had with ZCP270s as we've had none in
the past 4 years, although we do realize going forward that FCP270s are
best (but were not originally due to limited number of FBMs).
Jack Easley
Sr. I&C Technician
Luminant Power, Martin Lake Plant
Phone 903.836.6290
jack.easley@xxxxxxxxxxxx
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Hicks, Gaylon F
Sent: Tuesday, November 09, 2010 11:32 AM
To: foxboro@xxxxxxxxxxxxx
Subject: Re: [foxboro] One Mesh vs Multimesh
Worst case you only crash everything on one Unit with multiple networks,
but it will cost you more in hardware. We rigorously separate our
units, but then we're a nuke. It's still a good idea.
My best advice for mesh architecture is to make sure you can tolerate a
complete failure. Avoid ZCPs like they're a bill collector.
Gaylon Hicks
TVA - Browns Ferry
-----Original Message-----
From: foxboro-bounce@xxxxxxxxxxxxx [mailto:foxboro-bounce@xxxxxxxxxxxxx]
On Behalf Of Olsson, Scott
Sent: Tuesday, November 09, 2010 11:14 AM
To: foxboro@xxxxxxxxxxxxx
Subject: [foxboro] One Mesh vs Multimesh
What are the Advantages and Disadvantages of 1 Mesh for the entire Plant
vs a Mesh for each Unit
Scott Olsson
PNM Resources
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