AB PLC5 to Contrologix, Keeping Existing IO

Anyone out there with PLC5 to Contrologix experience? I am hoping to get some feedback.

I'm considering converting a PLC5 40E Ethernet to Contrologix, for support and expandability reasons. There also is the possibility of adding a lot more logic to this process and the 5/40E is already filled to the brim with stuff.

There are a few remote racks on RemoteIO and DH+ to other PLC5. I would like to keep the current IOs. So is this possible? If so, what would be the least painful way of doing this? I’m thinking of putting the Ctrlx in a small chassis then connect this new chassis to existing I/Os using either DH+ or ControlNet. Any words of wisdom would be much appreciated.

If the bulk of the IO is discrete then keeping the 1771-ASB's on Remote IO is probably going to be just fine. On the other hand if there is a fair amount of Analog or other Block Transfer Modules, especially in the 5/40E's local chassis, then you may well run out of BT speed when it all has to be done on R.I/O. In that case moving the whole lot to ControlNet would be worthwhile.

The other aspect to consider is what you want to do with the program. Although the PLC to CLX conversion utility does most of the work, often as not you will want to re-write the whole thing to make the best use of how the CLX structures data.

But overall this conversion has been done lots of times that I am aware of and works just fine.

In addition to what PhilipW posted the phrase "support and expandability" would make me opt for ControlNet irrespective of I/O type/size.

I did some work at a site in the UK where they used a Rockwell "trade-up" promotion to get ControlLogix to replace their PLC system (magnetic core memory, paper tape readers etc. etc.) but keep their widely-distributed 1771 I/O and putting it on ControlNet; probably not the kind of trade that Rockwell were expecting!

Thanks for the feedback. I expect to have do some conversion anyway to clean out unused code generated over the years. I will do manual conversion in any case. I have exp with Contrologix in the past so should not be a problem.

Now that you guys mentioned it, I agree it's probably a good idea to convert the remote rack from RIO to ControlNet as well. I don't believe there any analog on this system but I have to check.

Regards,

If you have just descrete I/O then DHRIO will work just fine.
Controlnet is good idea if you have unlimited budget and some downtime and will be good for future expansion.

DHRIO will work fine. The main item to look out for is if you have a lot of specialty/analog cards in the remote racks that you have to BTR/BTW too. If so, there is a technote that addresses some of the limitations of the DHRIO card. It can not handle as many simultaneous BTR/BTW instructions to different rack addresses as a PLC5. Find that info and read it. If you end up needing multiple DHRIO cards that may justify the move to ControlNet.

Darren