## Using Modbus RTU with the é!COCKPIT runtime

### **Content**
This page describes adding a modbus RTU device using the é!COCKPIT runtime.
In case a function block for your specific device is not present yet in this project. Please consider reading the [RS485 tips and tricks](../FAQ/RS485_tips_and_tricks.md) page if this is your first time connecting a RS485 device.

### **Assign the PLC serial port to the PLC runtime**
In order use the onboard PLC serial port from the PLC runtime this needs to be configured from the web based management tool:

<img src="../_img/RS485_éCOCKPIT_WBM.png" width="550">

Note that it's necessary to reboot the controller after a change to this setting.

### **Required libraries**
Make sure the following libraries are present in the project:
```
WagoAppPlcModbus
```

### **Using code to access the RS485 serial port**
A specific implementation example can be found inside the project in the 'PLC_PRG_RS485' program.