Modbus RTU is an open standard, meaning that manufacturers can build it into their equipment without having to pay royalties.
Almost as old as the first Programmable Logic Controller, the Modicon 084, which in those days was called a PC for programmable Controller. In today’s age of Internet connectivity and Web Services, Modbus’ unconnected message and simple request-response communication structure are almost quaint. It truly is as old as the hills and has the whiskers to prove it.
How to Transfer IO Configuration to logi.You might call the Modbus protocol the grandfather of industrial networking.RevPi Connect works w/o separate monitor/keyboard.How to Read RFID Signals with RevPi Core as Modbus RTU Master.Temperature Measurements with RevPi Core as Modbus TCP Master.Temperature Measurements with RevPi Core as Modbus TCP Slave.How to Use RevPi Core as Modbus TCP Master.How to Use RevPi Core as Modbus RTU Master.How to Configure RevPi Gate for PROFIBUS.
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:
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.