Compatibility Issues

I am starting a project involving 2 plcs. One (a remote plc) must be a SLC/05, however the other one (main plc) may be a contrologix. The main plc will have 60 Analog I/O and around 300 Digital I/O. Are these two easily compatible over an AB datahighway? The logic between the two is interlocked in both directions. If so, what type of communication protocol would be best?

A SLC5/05 is an ethernet SLC.

Is the main PLC going to control the remote PLC IO? Or just messaging between the two?
I would use a ControlLogix for the main processor, and communicate to the SLC using Ethernet. This is an easy task with these platforms.

Yes, the main PLC will control the remote PLC (SLC/05). What is the advantage of using a ControlLogix over other alternatives?

If you are intending on using the SLC chassis as remote IO for the main processor, I don't think that you can keep the SLC5/05 processor there. You would have to make it controlnet or RIO.
Can't you change out that chassis for ControlLogix or FlexLogix?

The logic between the two is interlocked in both directions.

Click to expand...

Yes, the main PLC will control the remote PLC (SLC/05).

Click to expand...

Interlocking logic is not quite the same thing as controlling logic. If the remote PLC is still "in charge" of its logic, with only interlocks to the main, then perhaps you can still use it.

The SLC/5 will be controlling its own process, w/ some inputs from/outputs to the main PLC (ControlLogix).


We have to use the SLC/5, as it is existing in the system.

Then you should have no problems. The ControlLogix will accept infomation from the SLC 5/05 in a variety of forms.

Say you only have 10 I/O that have to be "interlocked", and it is about 200 feet between them. Hard wires are an option at this distance and quantity. A multi-conductor #16 12/conductor cable may be all you need. If this is a student project in a training lab (your handle implies you are a student), this may be the cheapest, easiest solution.

Connecting a DH+ network between the two is probably your best option if there are many interlocks or the distance is more than 100 feet. In this case you will need a communications interface module card on each end.