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RS 5000 ethernet module issue

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#1 bishop

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Posted 28 July 2010 - 02:38 AM

Hi

we're using the RS loginx 5000 on a clients site, and about 3 weeks ago the PLC went into stop mode - but nobody noticed because the ethernet module kept transmitting the last data it received and so the SCADA showed that all was well. Is this normal?

#2 malc cope

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Posted 28 July 2010 - 03:14 AM

Hi

we're using the RS loginx 5000 on a clients site, and about 3 weeks ago the PLC went into stop mode - but nobody noticed because the ethernet module kept transmitting the last data it received and so the SCADA showed that all was well. Is this normal?


Is it a case of the ethernet module not keeping on transmitting but wherever the data is being recieved it is just not recieving any new data?, I have come acrzoss similar scenarios in the past, regardless of communication method used, where a PLC has failed and the last data recieved is what is seen, Idealy some kind of active watchdog handshaking would be used to monitor the link, so that failures would be noticed earlier

#3 Ken Roach

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Posted 28 July 2010 - 09:34 AM

When an Input module connection fails, the Input tag values remain at whatever values they were before the connection failure.

The usual method for detecting a failed connection is to use a GSV instruction to examine the Module object's EntryStatus value. See the Help file "GSV/SSV Objects" topic and multiple threads on this Forum and other Forums.


ControlLogix controllers have RUN, Remote RUN, Remote PROG, PROG, Recoverable Major Fault, and Unrecoverable Major Fault modes.

"STOP" sounds like "PROG" mode or "Fault" mode.... which one was it ? The controller cannot go to "PROG" mode without being commanded to do so, but it can go to "FAULT" mode in the event of a program fault.




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