Allen Bradley SLC Upgrade to Controllogix

Looking to upgrade an Allen Bradley SLC system to Controllogix.

The Main Rack will house the CPU(L71) and 6 devicenet cards(1756-DNB) to replace the SLC Processor and Devicenet Cards.

Any ideas or suggestions for things to watch out for. It is a big system, so we will be migrating one unit at a time. Common components probably at the very end.

rajy2r said:

Looking to upgrade an Allen Bradley SLC system to Controllogix.

The Main Rack will house the CPU(L71) and 6 devicenet cards(1756-DNB) to replace the SLC Processor and Devicenet Cards.

Any ideas or suggestions for things to watch out for. It is a big system, so we will be migrating one unit at a time. Common components probably at the very end.

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You don't mention the SLC processor, but, regardless, with a phased implementation like this, you will really find it useful to somehow establish a processor-to-processor communication like of some kind, somewhat fast.

As you go along, you'll find more and more reasons why one processor would have information the other would need.

In my experience.

The Devicenet will be a lot easier to setup. I usually just do the conversion and then remap to the new addresses for Devicenet and IO. Timer presets will be automatically rescaled in the new timer, but if you do any moves to the presets or accumulators you will have to rescale those manually. If you have an HMI that uses tags that match the SLC tags then do yourself a favor and select the option to create those tags in the Logix when converting. I have found that all PID loops will need to be re-tuned.
I have found it easier to make a new program in 5000 and put all of my usual code and user defined type and logic in. Then convert the SLC in a separate file and just cut and paste the parts I want to keep.

You can connect the 1756-DNB modules to the existing DeviceNets and configure its scanlist for Listen Only connections.

That will let you test all the converted logic in the ControlLogix, and compare your outputs to the output data on the DeviceNet.