AB PLC3 to ControlLogix


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Replacing AB PLC3 with AB ControlLogix. Problem with memory mapping in ControlLogix. We need to communicate to ControlLogix with existing PLC2, 3, 5 devices. PLC5 devices map correctly in the ControlLogix. PLC3 devices do not. Has anyone used PLC3 devices talking to ControlLogix?

I think the issue may be the same as using SLCs. In the PLC3 memory map, an 'I' file needs to exist for the calling PLC/SLC. If you are using DH+ and the Contrologix, which will appear as a PLC2 to the PLC3, is node 4 on DH+ via the 1756-DHRIO, the an I4 file needs to exist in the PLC3 memory.

I have used a PLC3 to talk to a SLC 5/04, via DH+ and this is what I had to do.