When you buy an I-7188E2 -MTCP controller, it already has the default Modbus firmware installed in Flash memory. The default firmware has the follows features:

• Supports VxComm technique for every COM port of controllers 
  If serial devices don't support Modbus/RTU, you can still access these devices. But need to install VxComm driver on host PCs and assign a COM port number to b to the remote COM port (of I-7188E2 -MTCP). After that, serial clients can access these remote serial devices via standard RS-232 functions.
• Allowed multi-client (or master) access simultaneously 
  Different I-7188E2 -MTCP controller supports different client numbers connect to. Please refer to our FAQ on web for more detail. 
  http://www.icpdas.com/faq/7188e/hardware/003.htm
• Firmware modifiable 
  We provide the Modbus SDK allowing users to develop their custom Modbus firmware.