Node-RED Modbus TCP can recover from communication errors automatically. Options are available to you the programmer to continue the Node-RED flow upon detection of these errors.
Broken Ethernet cable, Modbus Server power, and Node-RED Client offline are just a few of the errors that can occur on the industrial plant floor. Our Node-RED program must account for and be tested for each of these conditions.
We will be communicating Modbus TCP (Ethernet) to our Click Plus PLC. Using the catch node we will detect and display errors that may occur. Let’s get started. Continue Reading!
We will now be looking at simple data logging using a Click PLC with an Ethernet port. Node-RED will be used to communicate to the controller via Modbus TCP protocol. Information collected will be then stored in an SQLite SQL database. A Raspberry Pi 4 single-board computer will be used for the Node-RED collecting and storing. The update time will be two times a second (500 mSec). This method is ideal for quickly determining how things are operating.
Analysis or display of the information will be done with a spreadsheet. The spreadsheet will be run on a windows computer. Let’s get started. Continue Reading!
We will be installing an industrial USB to RS485 converter on our computer. The Waveshare USB to serial port is a 2-wire USB to RS-485 serial communication adapter for RS485 use. It does not require an external power supply or complicated configuration.
It has a Type A (plug) USB connector for the computer side and screw terminals for the RS485 connections. This is an industrial USB to RS485 converter that has an FT232RL chip inside. It features embedded protection circuits such as lightning-proof, resettable fuse, ESD (Electrostatic Discharge) protection, and TVS (Transient Voltage Suppression) diode, etc. All of these features are packed within a small form size.
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We will be installing the driver for this USB to serial converter and connecting it to our computer. Node-RED will be used to communicate Modbus RS485 protocol to a Solo process temperature controller. Let’s get started. Continue Reading!
Node-RED HTTP Request can be used to read any BRX Do-More PLC memory area. This HTTP (Hypertext Transfer Protocol) communication will only read information from our controller.
The BRX Do-More REST API is used to read information using a URL (Uniform Resource Locator) or web address. We will be using the HTTP request node in Node-RED to read information from our BRX Do-More REST API-enabled controller. Writing using Modbus will also be shown. This will all be done on our Raspberry Pi 4 single-board computer. Let’s get started. Continue Reading!
Node-RED can easily display interactive information to the user or operator using a web browser on your phone, tablet, or computer. Any device that has access to the network in which node-red is running.
We will be installing the node-red-dashboard palette. This allows us to create a live data dashboard user interface. (UI)
The information from our Solo process temperature controller will be displayed. Setpoint information can be set either by the dashboard UI or the Click analog input signal. This will be selected via the user interface. Let’s get started using Node-RED Dashboards. Continue Reading!
Node-RED can easily connect to industrial controls using Modbus communication. Modbus is a master-slave type of communication. Masters will always send the commands to read or write to the slaves on the network. The slaves will respond if the communication 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. Continue Reading!