Migration from SLC500 to 5000


Thread Starter


Hello all;

Some pointers/suggestions requested on the migration from various SLC500 PLCs to Contrologix5000. Our plant has a hundred or so SLCs - from 500 to 5/05 - some standalone and some networked. (The result of 40+ years of growth and ignorance of the future need to upgrade.) Any suggestions on how to handle this transition. My first thought is to contact our local AB distributor and have his techies have a look. Anyone out there with a history of such a transition? I'd like to keep our electrical staff involved to some degree but the scope of the job may make it difficult.
Contact your A-B rep. There is a class I took at McNaughton-McKay on mitigating a migration from SLC to ControlLogix, look into it.
There are a a number of ways that will be required to upgrade your PLCs, and as many considerations that will be required.

Almost all brick SLC500s can be handled well with micrologix, rewiring will be a must. Programs can be copied and pasted with slight changes due to the instruction set not being entirely equal.

Some of the SLCs can reuse most of the I/O hardware, through a module AB introduced some time ago, that allows a compactlogix to control I/O through Ethernet.

Other SLCs will require a controllogix if they have legacy networks (DH485, RIO, DH+).

A careful planning strategy must be followed to maintain compatibility with the rest of the controllers if networked. You should team up with a well seasoned Systems Integrator that can mate your needs and what's available and possible. Hope this helps.
Yes I agree to use the local AB distributor, However I would also balance that with a couple of integrators. Most of the time the integrator will look at the money side of the project where the distributor is more concern about how much hardware he can sell you. If you are using RS500, there is no reason you could use a compactlogix controller instead of a controllogix controller.


We had a bunch of SLC's that we wanted to migrate to ControLogix. The 1747AENTR module proved very useful. It plugs into the processor slot of the old SLC rack and gives you EtherNet connectivity to the ControLogix rack. It then acts as a remote I/O using the existing modules in the SLC rack.

There are some limitations to the type of I/O cards that it will support, but it sure saved re-wiring everything in our case. There is also a 5000 translation tool which will translate most of the SLC instructions to Logix platform. It misses some instructions (not many) but at least flags them for you so you deal with them individually. Considering the size of your project, sounds like a job for a qualified integrator.

Bob Peterson

There are a lot of things that could affect what you do.

Do you plan to change out the I/O or just the processors?

AB now has an Ethernet/IP remote I/O adaptor for the 1747 I/O racks so youdon't have to change out any wiring if you are willing to keep the I/O in place.

There is a program conversion routine that works pretty well.

One big gotcha is that a lot of people used RIO and DH+ (blue hose) for both RIO and communications with SLCs. AB has a DH/RIO card available for the Controllogix line that supports it quite well. Prosoft has some options as well.

You may have to look at replacing some RIO linked HMIs as well.

We have done a fair number of replacements of both SLCs and PLC5s, sometimes using ABs transition hardware, sometimes it is a gut and start over kind of thing. Often it comes down to how long a customer can afford to be down.

You might want to consider swapping out individual SLCs with compactlogix block processors on a one for one basis. That way you only affect one machine at a time.

Do you have up to date drawings in CAD format for the existing PLCs?

100 slcs being changed over would make for a nifty project. I would love to be involved in it.

Jeremy Pollard


good morning... as Bob Peterson said, I would love to be involved in the project.. something to get your teeth into :)

Having said that, each install needs to be looked at by way of machine control, network hierarchy, data acquisition, and process requirements.

You have an opportunity to add so much more to your plant by using the migration path as a need to re-develop the applications and for extensive data logging etc... much work I might add, but can achieve a great result.

Many questions to be answered to be sure... Tony_War's response is spot on..a planning strategy is a must - way too many sink holes you could/can fall into.
Get someone you trust to help pilot the ship...

Cheers from: Jeremy Pollard, CET The Caring Canuckian!
Crisis, necessity, change

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