Compact Logix Processor Redundancy?

I'm wondering if anyone has any experience or information on configuring the Compact Logix system with dual processors that will automatically switch over is one fails?

A customer has specified that they want Compact Logix, but also said they want automatic processor switch over. I'm not sure this is possible.

According to AB the FlexLogic processor can be used in this way using common I/O on DeviceNet. Does anyone have any experience with this?

Thanks,

Jeff

CompactLogix doesn't provide redundancy at the moment. If your customer wants a real redundant system you must use *******Logix with redundancy modules 1757-SRM. With this configuration you have automatic switch over if the primary controller fails.

Sessions

No redundancy with compactlogix and probably will not be in a near future.
Devicenet Flexlogix version is not a true redundnacy, 2 processors execute code in parallel and only one controls I/O. If it dies, second takes over.
Use ControlLogix redundancy - this is the only true redundand system.

It does not make sense that the CompactLogix have redundancy. Since this product is not hot swappable, there is not a chassis in which the modules reside, rather the backplane is built by plugging modules into each other in effect extending the bus. Because of these issues, it would be difficult or impossible to replace a failed processor with out shutting down the PLC. The Compact Logix makes sense for individual equipment control when you have multiple parallel units where single point failure could be handled by another piece of equipment starting such as pumps or other unit process equipment.

You should also consider the failure rates of the hardware when selecting a platform within a manufacturer's family of products to determine which to use if hot back up and redundancy is what you want. I would strongly recommend using Control Logix if you seek redundancy.