cruxader
Joined: 13 Sep 2003
Posts: 10
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 14 Sep 2003 20:27 Interesting PLC network problem |
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We run a network of around 50 allen Bradley PLCs (SLC 5s) which are networked to control our facilities.
In the past fortnight between 9~13 of the PLCs mysteriously lost network connection at the same time (over 3 occasions). The error code was that the MAC suffered a hardware failure. Condition is recoverable but communications cannot resume.
In otherwords, must power cycle the affected PLCs.
The local agent and our facilities ppl are at their wits end. I have been asked to advice them
Any ideas?
What I have found so far:
1. Some sub-standard LAN cables have been identified and replaced. But there is no impact on the outage.
2. Failed PLCs are spread over more than 1 network hub/switches.
3. The PLCs network was connected to company intranet though it was isolated between 2nd and 3rd outage.
4. All but 1 of the affected PLCs had Network daughterboard version 2.19 (Version 2, Firmware Revision Number 19). The sole exception had 2.33. We have assortment of 2.19, 2.33, 2.40 & 2.50s. Not all 2.19s failed.
5. The PLCs are linked to half-dozen HMI PCs.
6. During the 2nd outage, the link between the PLC subnet & the company intranet went down too.
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