Ethernet Modbus TCP/IP

[Sleepy Wombat 27]

Jay, or anyone, is their any ways besides using a gateway product to get the Omron Ethernet modules namely CJ1W-ETN11 / 21 to talk Modbus TCP. I understand that the Omron Ethernet unit uses FINS commands with UDP or TCP, the main commands being SEND/RECV/CMND. Although it can communicate with Socket Services I do not believe that it can communicate on Modbus TCP. Are their any Omron products available that you are aware of that can ??? Do you think that the Omron ONC would be able to do it ??? I look forward to any comments.......

[Jay Anthony 118]

Any development on the ONC has been curtailed due to the dang (Chris's filter must be working) Schneider patent. Modbus_TCP_IP_Fun03_16_2.zip

[Jay Anthony 118]

The above program seems to be for Modbus Slave TCP.

[Babbster 0]

Hello All, Has anyone tried this? I have a need to run 9 non-Omron touchscreens (using ModBus TCP/IP) to one CJ. Steve B

[Nibroc 4]

... The ETN11/21 ethernet units are not restricted to only FINS, they can transmit any data. The SEND, RECV and CMND functions use FINS networking protocol, however 'non protocol' communications can be implemented similar to RS232 mode on a serial port. Both UDP and TCP are supported, and can be manipulated using Ladder code or better yet the Omron FB's provided for this purpose. (under ETN in the Omron FB library) Modbus TCP can be implemented, (see Jays example). I have also posted an example modbus TCP 'client' (master) in the downloads section. http://forums.mrplc.com/index.php?autocom=downloads&showfile=524 This example was used to 'read' a couple of Modbus TCP analog input units in a coolstore. Implementing a generic type 'server' (slave) could also acheived using ladder and/or FB's. One great thing about Modbus TCP is that the CRC checksum is dropped, as the ethernet hardware itself looks after error checking! Specifications for Modbus TCP can be found at Modbus.org. Nibroc

[jaccov 0]

Can this work with Mini-Scada Pro see link http://forums.mrplc.com/index.php?autocom=downloads&showfile=527 Please give me some advice.

[Nibroc 4]

To communicate with Mini-Scada Pro using Modbus TCP you would need to implement a Modbus 'Server' in the PLC. The examples attached above are Modbus 'Clients' so are not suitable. It is possible to implement a Modbus 'Server' in the PLC, however this could take 1-2 days for an experienced PLC programmer. Advanced knowledge of Modbus, Modbus TCP, PLC/ETN unit would be required. I would use the Omron FB's supplied for TCP communications including 'TCP Open Passive', 'TCP Receive' and 'TCP Send' to help implement the Modbus 'Server'. The program would need to (in sequence): 1. Open a passive TCP socket and wait for the remote connection to be established - in this case Mini Scada Pro would complete the connection by opening the socket. (Use FB TCP Open Passive) 2. Wait Until a Modbus Request is Received (Use FB TCP Recv) 3. Process received request to determine what data to send 4. Send Modbus data (Use FB TCP Send) 5. Return to step 2 Conclusion: Yes an Omron CS/CJ PLC could communicate with Mini Scada PRO using modbus TCP. However if you are not an advanced PLC programmer looking for a 'challenge' I suggest sticking to the serial hostlink provided!! Hope this helps Nibroc

[Sleepy Wombat 27]

Even then I think that I would bite off all my nails first....I would tend to go through a gateway, two -three days of my time would be way to much to justify, a simple gateway would achieve this in half the time and i would have some hair and finger nails left as well....