Node-RED Modbus RTU / TCP Communication

Node-RED can easily connect to industrial controls using Modbus communication. Modbus is a master-slave type of communication. Masters will always send commands to read or write to the slaves on the network. The slaves will respond if the transmission is directed at them. We will be installing the node-red-contrib-Modbus palette. This will allow us to communicate Modbus serial (RS485) RTU to a Solo process temperature controller. We will then use Modbus Ethernet TCP to communicate to a Click PLC. Note: When using Modbus TCP (Ethernet), the master is referred to as the Client, and the slave is a Server. Node-RED will be used to create a single Modbus flow. We will communicate to our Solo process temperature controller using Modbus RTU on a serial RS485 network. The present and set values of the controller will be read. These values will then be written to our Click PLC using an Ethernet Modbus TCP network. A set value from an analog input on the Click will be used to then write to the Solo. This will happen every 200 milliseconds or 5 times per second. Let’s get started using Node-RED for Modbus communication. In this series, we started using Node-RED in some of the following ways: Installing the Windows Software https://accautomation.ca/node-red-installing-the-windows-software/ Video https://youtu.be/xGzH2Hv31WA We will continue with the following: Connect to our industrial equipment using the Modbus protocol. Additional information can be found on our website at the following URL: https://accautomation.ca/node-red-modbus-rtu-tcp-communication/ Future information will include the following: Display Information on a user interface, HMI, or dashboard Log information into a database View information in the database through spreadsheets such as Excel.