OMRON CJ1M-CPU11 Modbus addressing


I am currently converting a citect project to ignition and I am trying to connect to an OMRON CJ1M-CPU11 PLC via the ignition Modbus TCP driver. The PLC has an Ethernet CJ1W-ETN21 module. Through ignition I can connect to the PLC but when I try to address tags (according to the Modbus Ethernet addressing in the ignition user manual) I get errors stating that they are not connected. I am a bit of a newbie when it comes to OMRON PLC’s and Modbus and would appreciate a little advice for the address of the tags in ignition. I have attached a list of the tags I pulled from Citect which are the same addresses in the PLC.

Any help is appreciated.
variable.xls (29 KB)


Although I believe that it is possible to communicate to some of the addresses within the PLC I’m not sure that the full range is available over Modbus. From experience Omron + Modbus can be painfully slow. , gives a brief overview of the fuction block and available addresses.

You might well find that it would be easier to use OPC to commuicate between the PLC & Ignition.

Best Regards

Thanks Kevin for your response.

I am trying not to change the PLC code to make the communication to ignition, but the original citect project communicated with the Omron PLC using the OMFINS3 protocol. This protocol accessed the plc addresses directly but it seems that i need to map the addresses to the registers in the plc to be able to use the modbus protocol.

When you say use the OPC server to communicate with ignition do you mean software such as Kepware, to be used as a middle-ware between the PLC and ignition?

Thanks again for the help.

Ignition’s OPC-UA server has it’s own Modbus driver, so if you do go ahead and map the data into PLC to Modbus registers you should be able to access it like that.

Alternatively, you can use something like Kepware and its FINS driver to read from the PLC, then make an OPC connection from Ignition to Kepware to get at your data.

I thought that the OMFIMS3 protocol was for serial comms, although I haven’t touched Citect since V7.21 so I could well be wrong.
My personal preference would be to use Kepware / Topserver and link via OPC as it works like a dream. But then again I’m just lazy… opps I mean efficient with my time :smiley: