CompactLogix Failover

Hi,

I would like to setup two Compactlogix PLCs so if one fails the control of the I/O will failover to the second PLC. The application can handle the a non bumpless transfer.

I have 2 compact logixL30ER, a Stratix 1783-EMS08T/B Switch and a 1747-AENTR connected to an I/O rack with SLC I/O

In the logic I state that if one CPU runmode is not running I inhibit the connection, and the second PLC will be given ownership of the I/O rack.

I see a fault on the I/O Rack and switch connection properties.
Code 16#0106 / Module owned and configured by another controller

It seems that it does not fully release the connection from the CPU that originally was connected.

Is there a way to fully release force the connection to close?

Thanks

CompactLogix isn't designed, advertised, promoted, engineered, or supported to do this.

So why ?

This is the hardware that I have available . That is why.

The attached document describes how to handle a similar setup in logic using Flex I/O and compactlogix processors

https://www.academia.edu/13392302/XX_XX_XX_XX_XX_XX_L33ERM_1_Front_2_Rear_Hot_Backup_Application_Technique?auto=download

I think you could do a homebrew failover setup if you had a second set of I/O modules dedicated to the second processor, wired in parallel with the original I/O modules where possible (Digital I/O?), or switched via relays or use splitters where not (analog?). This might be pretty clunky but would work.

Another option would be if you used third party remote I/O such as Omron, and configured it to be in the I/O tree of both processors. When one processor fails, the other could be set to grab it via clever network tricks. There would be some intricate coding for a clean handover, and certainly a delay of at least a few seconds.

As Ken has pointed, CompactLogix does not support redundancy. That's the official position:

TN946937 CompactLogix: Redundancy system (Access Level: Everyone)

I believe there was a procedure to get a pseudo-redundancy using CompactLogix, Flex IO and DeviceNet, but I don't know how safe and reliable it was.

Is this a homework? Or do you work for a company with a low budget?

Anyway, there's another technote:

TN473501 CompactLogix Controllers Supporting Hot Backup and Software Output Switching Applications (Access Level: TechConnect)

Did you check the IO configuration on pg. 13?

The application can tolerate the bump in transfer if one PLC fails. It is a slow timing application that sequences through the I/O outputs. This is an application I need to test, I know that Redundancy is not supported on compactlogix officially but it seems to be possible to configure a pseudo redundant system that allows a failover to happen by Inhibiting the connection to the I/O. This is what I am trying to get working.

As I mentioned I get an Code 16#0106 / Module owned and configured by another controller when I try to do the failover.

Ken Roach said:

CompactLogix isn't designed, advertised, promoted, engineered, or supported to do this.

So why ?

Click to expand...

Thats whats I thought too Ken, but Rockwell are selling it as a solution in Sweden. I was told I didn't need ControlLogix for Redundancy by our commerical Engineer.

NOG said:

This is the hardware that I have available . That is why.

The attached document describes how to handle a similar setup in logic using Flex I/O and compactlogix processors

https://www.academia.edu/13392302/XX_XX_XX_XX_XX_XX_L33ERM_1_Front_2_Rear_Hot_Backup_Application_Technique?auto=download

Click to expand...

Did you read this?

Rockwell Automation Publication HIGHAV-AT001B-EN-E – December 2012 7
Disadvantages of This Technique
When considering this technique, be aware of the following key limitations.
Outputs


Not bumpless. Outputs can revert back to their safe state temporarily during a switchover.


Only 1756 and 1794 output modules are supported.


Only Ethernet I/O modules are supported.


Only remote I/O is supported, not local I/O.


Input modules must be located in a different chassis from output modules to reduce the amount of ladder logic and the duration of the switch-over time.

Click to expand...