RSView ME with Primary and Secondary CompactLogix

Hello Smart People

I'm starting research on a new control system. I will have a single HMI running RSView ME, and I need a primary and backup Compact Logix controller. All the I/O is remote Flex IO on ControlNet.

If the Primary PLC faults or fails in some way, the secondary PLC will act as a backup. This does not need to be bumpless or automatic, but it does need to be relatively quick and able to do without a technitian needing to connect a laptop to the system. Its not a critical system, and using ControlLogix with SRM is cost-prohibitive.

There are two things I will need to figure out... when swapping to the secondary PLC, I will need for the secondary to take ownership of all the I/O connections without reconfiguring RSNetworx manually. Also, my RSLinx Enterprise shortcut to the Primary PLC will be no good, so I need to figure out a way for the secondary to act as the server.

For the second problem, I am thinking that perhaps having two runtime projects, each one with a shortcut to a different controller, will suffice. I can write a batch file to shutdown one runtime and start the other one when the switchover to the backup PLC is necessary. If there is an easier way to do this, please offer suggestion.

I'm not sure how to programmatically allow the secondary PLC to take ownership of IO. I've never used multiple controllers in this way before. I'm gonna start reading manuals and knowledgebase articles, but if anyone has some quick tips it would be appreciated.

BTW I think its crazy that we can't just take another PLC and plug it in with the flash card and get going again. But the bosses want two PLC down there, so.... I'm sure it can be done, I just gotta figure it out.

Thanks in advance.

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Before logix redundancy with SRMs Rockwell had software redundancy that was abandon while ago once hardware redundancy became available.

It was using multiple MSG instructions for a crosscheck as primary owned I/O and secondary had I/O inhibited.
Once Primary failed and secondary determined that, it enables all I/O and takes control over.

But this was for controllogix, I am not sure if this will work with compactlogix.

Also I heard that software application will available again in a near future: it is faster than SRM system because it has no crossload time.
You will need to check this with your local rockwell guy - techsupport does not deal with this.

OK I think I've come up with a much better idea. And I think I can sell it to the bosses.

Instead of all this retarded programming, I think I can do an old-fashioned switcheroo.

I think I'll set up both CompactLogix chasses with identical programs and ControlNet nodes. Then I'll connect the power supplies to opposite throws of a latching relay. I'll have a spare Flex output energize the relay coil in a safe-state mode activation when communication is lost with the first PLC. Then the second PLC should start up, go into run mode, and report the latched state of the relay to the operator from an input, who can check out the problem.

I can't think of a reason why this won't work, and it doesn't require any extra programming and ****. I should be able to sell this idea to the bosses

Any thoughts are still welcome

$

PS. LOL @ answering my own thread, hehe

The problem with relay is that relay may trip and switch to secondary but how you guarantee that I/O ownership will be taken over ie I/O may still think that it is owned by the primary?

You can probably find coax cable swticher pasternack relay http://www.pasternack.com/ and switch coax line from PRI to SEC. This will let you keep both PLCs running, perform crosscheck and crossload data if necessary.