# Adding a Modbus RTU master

A UR20-1COM-232-485-422 module can be used as Modbus RTU master over serial line.

1. Open the device view.
2. Add a UR20-1COM-232-485-422 module to your configuration.

1. The Modbus RTU master is inserted subordinate to the UR20-1COM-232-485-422 module.
2. The UR20-1COM-232-485-422 module is automatically parameterised for the use as Modbus RTU master over serial line (RS485).

You can change the parameterisation of the UR20-1COM-232-485-422 module to suit the requirements of your Modbus RTU network.