Re: [foxboro] fbm failed messages

  • From: Corey R Clingo <corey.clingo@xxxxxxxx>
  • To: foxboro@xxxxxxxxxxxxx
  • Date: Mon, 27 Jun 2011 09:41:56 -0500

We still see it too, and we do not have any FBMs running ladder logic.  We 
did the isolated-DIN-rail hack that Foxboro recommended but that didn't 
help.

The problem seems to lie in the coax cabling, or the CP's implementation 
of it**.  The best solution for us so far has been to use fiber in the 
fieldbus network as much as possible.  On the installations where we 
connect the thin white coax from the elevator plugs directly into a fiber 
converter (the newer Black Box one, not the crappy 1st-gen model that 
Foxboro initially offered), we see few if any of these errors.
 

Corey Clingo
BASF Corp.


**Side note: anyone who has ever worked with any kind of coax cable 
networking knows it's finicky, and I still am incredulous that Foxboro 
chose to use it when 10baseT (and maybe even 100baseT) was commonplace.





From:
tjvandew@xxxxxxxxx
To:
foxboro@xxxxxxxxxxxxx
Date:
06/27/2011 09:18 AM
Subject:
Re: [foxboro] fbm failed messages
Sent by:
foxboro-bounce@xxxxxxxxxxxxx



We saw the intermittent failure and module switch over from fieldbus A to 
B to A... Also.  It appeared to be more prevalent on FBM's running ladder 
logic, presumably because of increased data load of passing IFL's and 
OFL's as well as CIN's and COUT's across the fieldbus.  If you force the 
fieldbus to stay on one bus, like A ONLY, the error messages will cease 
but then you give up bus redundancy for all FBM's attached.  If you leave 
it on two busses it will constantly switch when it hits a COMM ERROR.  On 
one bus it will retry on that bus and doesn't send an error unless it has 
multiple consecutive failures on that bus.  Solution, live with the errors 
and bus switching or run on one bus only.  I don't think Foxboro ever 
really solved this problem.  How about it Dave Caldwell, is this still an 
issue for you?
Tom Vandewater 
Sent from my Verizon Wireless BlackBerry



 
 
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