PLC2 To PLC5 Retrofit

I need to swap a PLC2 processor out with a PLC5 processor. I have been told that the chassis and all associated IO (discrete and analog) will not have to be changed, only the processor. I know some program modifications will have to be made. Are there any potential problems with swapping the processors, such as the chassis not being right or some of the IO not working? Any thoughts on the matter are appreciated. Thanks.

You're usually in good shape when you don't replace the I/O, because the old RIO adapters, chassis, power supplies, and I/O cards already work with each other.

Which model of PLC-2 ? You'll have to change the power supply on the CPU chassis to one that works with PLC-5 processors. Power supplies on remote chassis can be retained.

There's an excellent and comprehensive Technote on this on the Rockwell Knowledgebase; it contains more info than I can easily post here.

Go to the support.rockwellautomation.com site, log onto the Knowledgebase, and search by document number for A16647.

This document covers the hardware issues thoroughly; program conversion is a separate topic.

Thanks. I'll check out the tech note.

I seem to remember that some chassis are not compatible with the PLC 5 processors, physically that is. It was some time ago but I remember having a PLC 5 not being able to slide all the way into the chassis as there was a plastic power supply connector on the bottom of the processor slot that was in the way. I could be wrong but it may have been a series A chassis.

Hopefully the technote mentioned gives this information.

grs

You should be able to swap out the PLC/2 fairly easy. If it is a 2/16 with the power supply built in you'll have to add a 1771-P4S power supply to an open slot in the chassis or use a 1771-P7 external power supply. Check the jumper on the chassis and set the dip switch.
If the program is very large you will want to use the conversion program to import the logic to the new project. Watch out for SQO or SQI instructions and also the any counter done bits. I have converted about 6 PLC-2/16's to PLC-5/15's.