The Modbus RTU Slave default value is set as 12 for the first 10 holding registers.

If using a USB-485 Converter, add the following line in /etc/CODESYSControl.cfgĬonfigure the Modbus RTU Slave channels, one for Read Holding Registers and one for Writing Multiple Registers.Add the following line in /etc/CODESYSControl.cfg.If using the default RS485 port on the device, the serial port needs to be assigned in Codesys. If an extra USB-485 converter is attached, the correct COM port must be identified. Under General/Serial Port Configuration tab of the MODBUS_COM device in the CODESYS tree the COM Port will be selected as follows: Configuring MODBUS RTU Serial PortĪdd the following line in /etc/CODESYSControl.cfg The CODESYS Control device target for the example will then be changed from multi core to single core. Select CODESYS Control for Raspberry Pi SL.Right-click on the “Root Device” CODESYS Control for Raspberry Pi MC SL in the CODESYS device tree.If you have a license for Single Core, you can change the target like this: Select a RevPi Core or Compact instead of the RevPi Connect and name the device accordingly.Right-click on the RevPi_Connect in the Codesys device tree.You can adapt this example for RevPi Compact or RevPi Core. The application logic is implemented in the POU_Modbus, which is responsible for reading the holding registers and writing back to the holding registers for both Modbus TCP and Modbus RTU slaves. Both Modbus masters are running on the RevPi Connect and each has a slave connected. The following figure shows the CODESYS device tree overview of the example. In this case, the application should read the holdig registers of the Modbus slaves 0-9 and copy them to the holding registers 10-19. In addition to the RevPi Connect, we need one slave each for Modbus and Modbus RTU for this example. In this example, we want to run a Modbus TCP master and a Modbus RTU master on the RevPi Connect+ CODESYS with CODESYS Control for Raspberry Pi MC SL.

Modbus rtu to tcp