CJ2M ETN21 Modbus TCP/IP Server

[Ianpatel]

Hello everyone,

I am having issues with modbus tcp/ip communication. The setup is:

CJ2M-CPU35:

Unit number: 1

IP: 192.168.10.01

Subnet: 255.255.255.0

ETN21:

Unit number: 2

IP: 192.168.20.01

Subnet: 255.255.255.0

Routing table:

Network 1: 192.168.10.01

Network 2: 192.168.20.01

There are several other Omron PLCs in Network 1 with IP 192.168.10.XXX. I am using RECV instruction to get some tag information from other PLCs on this network. Regarding Modbus TCP/IP, ETN21 in Network 2 needs to send these collected tag information to a different system on 192.168.20.XXX network. II have data stored in CIO 0 to CIO 4 and D0 to D10 registers and using MTCP_ETN_Server FB without any changes but I am not able to achieve communication. There are no errors on FB and "Connected" bit remains at 0.

I can post the program with routing table if needed. Please let me know if there anything I should check. 

[Ianpatel]

Hello pcmccartney1,

Could you please elaborate? There is no gateway settings. PLC is connected to Network 1 and I have made ETN21 to be Network 2 with unit number as 0.

Also do you recommend any software I can use for testing modbus polling?

[Michael Walsh]

It appears that 192.168.10.1 and 192.168.20.1 are both referring to the same PLC.  192.168.10.1 is the IP Address associated with the port that is built into the CPU and 192.168.20.1 is the IP Address associated with the CJ1W-ETN21 module that is plugged into that PLC.  So, there is no router and therefore no issue with default gateway.  

It is very difficult to assist without the code however.  @Ianpatel

[Michael Walsh]

I would recommend Multiway.  It was developed by an Omron Engineer.  You can find it here:

https://www.support-omron.fr/details/logiciel.php?id=2017-07-28%20-%2015-42-06%20-%202107046460

[Michael Walsh]

Actually, Etherway (follow up to Multiway) would be better:

https://www.support-omron.fr/details/logiciel.php?id=2017-07-28%20-%2015-34-21%20-%20636541960