Intermittent Arcnet Communications

Dear Arcnet guru's,

we have 2 Frame 7EA's in service for about 4 years or so. Recently we have started to encounter intermittent loss of cummunication issues between the EX200 exciter and the MKVI controllers. Since the EX2000 only talks Arcnet, and the MKVI only talks Ethernet there is a UC2000 controller (MKV Controller) in the middle that is the mailman/interpretter. The problem is very intermittent and started with the first unit shortly after a normal hot gas path outage.

About a month later the 2nd unit started to do the same thing. At one point the first unit acted up long enough to get a scope on the ARCNET line and verify that traffic was not normal. Manipulating cables on the ACNA card, LDCC board, and UC2000 arcnet card resolved the problem, unfortunately not sure which "manipulation" fixed the problem. The second unit continues to error at times, never long enough to get a scope on it.

I have performed the same "manipulation" to all connectors on this unit, and replaced the coax cable as well, but still having issues. I see contemporary controls offers an Arcnet analyzer that I am considering trying, but its not cheap. Does anyone have any suggestions or recommendations? So far I have been able to do certain things, but we are online and not scheduled for a shutdown until late October, unless I trip it accidentally before then!!!!
 
We've been able to clear up EX2000 communication failures by removing some of the tension on the coaxial cables which were wire-tied together with other cables going into the processor board in the EX2000.
 
JumboJet,

thank you for taking time to reply. In our case as it turned out I found that we were experiencing failures of the PC104 arcnet cards on the UC2000 controllers. We purchased a arcnet analyzer from the company that manufactures the arcnet cards, contemporary Controls. I was able to find that the the arcnet cards were failing at times, jambing the communications. In our case we had 4 arcnet cards in use, 3 of them were failing. We did not find our why they failed all around the same time, contemporary controls repaired the cards by loading "new drivers". During our next shutdown I plan to install the "repaired" cards to prove they are fixed. But replacing the cards during a shutdown last fall has repaired all our problems. Thanks again for the reply, it reminded me I had never updated my post.
 
We are using Arcnet in communications on a Printing Press between PLCs and are experiencing intermittent failures that cause data corruption in word interchanges between PLCs; how did you like your Arcnet Analyizer; good points and bad as well

Bklemp
 
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