Node-RED and a Low-Code Approach to Automation

Over the past decade, many different programming suites have been released that take a low- or no-code approach to creating applications. The purpose is to create an easier user experience without sacrificing the flexibility that comes with custom programming.

Low-Code Versus No-Code

These interfaces will often make use of drag-and-drop style programming with graphical representations of canned functions or operations. Users can create simple to complex programs in a matter of minutes instead of days or even months.

The collaborative robot industry has adopted this programming style to create simple, intuitive interfaces that enable end users to program robots quickly, without prior programming knowledge. Ladder logic, the most popular programming language for PLCs, could be listed as a form of low-code programming, with its graphical interface and function blocks that are used in place of operators and functions.

Figure 1. The Node-RED logo. Image used courtesy of Node-RED

Node-RED, a graphical low-code IDE, has recently become popular with the IIoT industry for its ease of use and versatility of deployment hardware, and the software is finding its way onto many IPC platforms, useful for sharing data between local and cloud applications.

Figure 2. Programming computer applications from scratch. Image used courtesy of Unsplash

The Node-RED Interface

Built on Node.js and JavaScript, Node-RED is a function block diagram IDE that can be deployed virtually anywhere Node.js can be installed.

The purpose of Node-RED is to process and transfer data (numbers, strings, and boolean values) between devices, based on events. The IDE mostly builds backend applications that are capable of controlling I/O, communicating with devices over industrial protocols such as OPC UA and TCP/IP, and connecting to databases. With its native web-based core, Node-RED can also make use of popular web protocols such as HTTP, MQTT, and Websockets.

For a frontend environment, Node-RED offers a library of UI controls that can be used within the application to allow user interaction. With the Node-RED dashboard installed, you get a full-stack environment capable of creating edge server applications that can interact with factory equipment and IT infrastructure.

Figure 3. An industrial Raspberry Pi, likely being used as an edge server. Image used courtesy of OnLogic

Living On The Edge

The IIoT and Industry 4.0 movement is mostly about devices communicating with IT equipment. This will often require an edge device that runs applications and can communicate with OT devices and IT devices. An edge server will typically live in the control panel and be connected to both the machine network and the plant network. The server can then collect data from the machine then push the required data up to the IT servers for further analysis. Node.js has the capability of communicating with these devices, but you will need to have some level of programming experience to develop an application, or you can use Node-RED.

Using Microcomputers As Edge Servers

The Raspberry Pi is a single-board microcomputer. It runs a version of Linux and has become very popular with DIY and hobby electronics enthusiasts. The Pi has become so popular that there are even industrial versions with DIN mounting features and industrial cases, like the Factor series IPC from OnLogic.

With Node-RED being JavaScript-based, it easily installs on a Raspberry Pi. Once installed and the Raspberry Pi library is configured, the Node-RED interface is capable of reading and writing to the board's inputs and outputs on the 40-pin GPIO. In virtually seconds, you can have an application that can read inputs, set outputs, and have a user interface, all running on a computer the size of a credit card.

Figure 4. Node-RED applications of a temperature controller. Image used courtesy of the author

Node-RED Interface

The interface is accessed by entering the IP address of the device. Node-RED is installed in a web browser. The pallet is located on the left side of the screen and contains all the nodes accessible to your project. Additional nodes can be installed via the pallet manager, similar to NPM packages. The right side contains node properties, debug windows, and dashboard configurations. Each program is made up of flows that consist of nodes that perform different operations on the payload, such as change, switch, delay, and function. The payload can be a string, an array, or a JSON object, and will flow through the nodes from left to right. The source of the payload can be from the dashboard, the hardware I/O, or the communication nodes.

Multiple flows can be added, and payloads can be passed to the different flows, or you can store payloads in the context stores. All these features allow the user to create well-laid-out flows that are easy to read and understand.

If there isn’t a node that does what you want, you can always use the function node, which allows you to write JavaScript code that can take inputs, manipulate the payload, and output different results. If you don’t want to program it yourself, the pallet manager has over 5,000 different nodes that are created by the Node-RED community and can be installed for your use without any licensing fees.

Figure 5. A Node-RED dashboard for an automated cellar with heating, cooling, and setpoints. Image used courtesy of the author

Node-RED Applications

With the intuitive interface, supported communication protocols, and the community forum, the possibilities of different applications are almost endless. The Node-RED documentation pushes the IIoT applications, such as HMIs, edge servers, and data acquisition systems. With devices like Opto 22’s Groov RIO PLC or Bosch Rexroth’s ctrlX Core IPC supporting Node-RED natively, you could build an entire automated machine using Node-RED for both your control logic and HMI.

The next time you are looking at building an automated project, have a look at Node-RED and the many different devices it can be installed on.