Omron Hostlink to West 6100 RS422


Thread Starter


How do I connect Omron PLC CS1G-CPU-43H using a SCU21-V1 card to WEST Temperature controlers using RS422?? I am brand new to Omron. We have Omron CX Programmer 4.0 if that is any help. Thanks.
If you are using RS422 it is obviously a serial protocol. You will require CX-Protocol to write the code for the serial unit to communicate with the West device. You will also require full details of the protocol that the West device uses. It is really very easy.

If it is only Modbus RTU, contact me at [email protected] and I can send you an RTU protocol that I use all the time. You will still need CX-Protocol to program the card.


The SCU21 is an intelligent communication module. You will need to set up what is called a protocol macro. This lets you define a communication protocol, upload it into the module, and your ladder program is then able to just select messages to fire off, and get the replies back. This eliminates the need to try to do the comm overhead using the ladder logic.

The software for setting up the protocols is called CX Protocol, and is not for the faint of heart.

I have found, however, that OMRON tech support has already written MANY protocols, so try calling them and see if they have something that you can just load in and go. If not, they will frequently write the protocol for you, provided that you let them keep it and share it with others.

I have done both ways (write my own, and have one written for me) and it works very well. In fct, I have another to write in the next 2 weeks! <G>

Good luck! Contact your distributor, and they can help you get it done. Otherwise, 1 800 55 OMRON in the US works to get to tech support.

--Joe Jansen
Good day,

Question: have you written a modbus driver and used the Omron PLC as a slave? Please advise.

Kevin Shin