Modbus TCP can be programmed in M-Duino PLCs.
Once the Arduino IDE is configured according to Industrial Shields requirements
http://blog.industrialshields.com/es/ethernet-shield-libraries/, the follwoing library can be used to program the M-Duino as Modbus TCP slave.
Basically, this example links holding registers 40000, 40001 and 40002 to outputs Q0.1, Q0.2 and Q0.3 of the M-Duino. In this way these 3 outputs can be operated via a Modbus TCP master. You will have to modify the IP address and network parameters according to your LAN.
An illustrative and simple example to test the application is with the following android free app. https://play.google.com/store/apps/details?id=com.bencatlin.modbusdroid&hl=es
Which will allow you to operate the M-Duino outputs via your smartphone. You only need to set the IP address of the slave and you can begin controlling the M-Duino remotely.
Now you can simply remotely control your M-Duino.