The COM2 port can be configured as Modbus RTU Client or Modbus RTU Server. In this case, it is used for data communication with standard Modbus RTU devices (device firmware version 2.2.X or above). It can also be configured as "EM Bus" or "EM1 Bus", indicating that the controller is connected to an EM or EM1 I/O extension module. You can select as needed at "Device Configurator interface".