For many types of machinery and test equipment, there is a great need to perform basic automatic control functions, or even just sensor monitoring. Developing hardwired automation is cumbersome, and many digital automation platforms are complex and expensive. Designers need right-sized solutions for these applications.

Figure 1. The AutomationDirect CLICK PLUS micro-PLCs are provided in an industrial-grade stackable micro-modular format, with simple and free software so users can quickly create automation and cloud-connected IIoT solutions for machines and test equipment. (Image: AutomationDirect)

Today, even the smallest and least expensive programmable logic controllers (PLCs) have advanced to a point where it is practical and economical to perform not only basic control and monitoring tasks, but also industrial internet of things (IIoT) implementations and cloud connectivity. Micro-PLCs are not just for relay replacement anymore, they are often also the best and most affordable industrial-grade control and IIoT solution.

For any type of equipment automation, users are primarily concerned with functional, safe, and reliable operation. This can often be achieved with electrical hardwired pushbuttons, relays, and indicators.

A far more capable option is to use digital electronic control platforms, opening the door for users to perform more precise control and extract much more data. Modern equipment is likely to incorporate increasing quantities of sensors, some wired, others wireless.

“Intelligent” field devices are revolutionizing the amount of available data — if the digital platform can access it via serial or Ethernet connections. Most users would like the ability to connect with all available data sources so they can monitor, optimize, and proactively maintain their systems.

Smaller automation projects with traditionally wired devices — typically around 100 input/output points or less — usually call for a basic instruction set, which can be handled by standard micro-PLCs. However, many applications require more functionality, which can only be delivered by newer modern micro-PLCs (Figure 1).

Figure 2. Built for industrial installations, the AutomationDirect CLICK series of micro-PLCs can connect with all types of OT field devices, while the newer CLICK PLUS version includes IT-friendly features like Wi-Fi and MQTT. (Image: AutomationDirect)

Common applications may also need capabilities like high-speed counting, PID loop control, and mathematical computation — and all these functions and more are now supported by many micro-PLCs. Performing the IIoT role requires a micro-PLC to natively support operations technology (OT) protocols like ASCII, Modbus RTU/TCP, and EtherNet/IP, as well as IT protocols like MQTT, DHCP, SNTP, and DNS. These features enable the micro-PLC to act as a bridge between field devices and onsite or cloud-based IIoT platforms.

The micro-PLC should be modular for flexible and scalable input/output capabilities, and it should also include micro-USB and wired/wireless Ethernet connectivity options. Wireless is particularly attractive because it significantly reduces sensor installation costs. Of course, any network-connected device must include cybersecurity measures, such as password management, encryption, port management, and more.

Modern micro-PLCs can be designed into new equipment, but they also play an important role for retrofitting existing systems. By adding a micro-PLC in parallel with existing controls, users gain the IIoT connectivity they need, without impacting the underlying automation.

Because machines and test equipment are more highly instrumented than ever before, and because users want to access all available data for deeper analysis, there is a significant need to bridge field devices to higher-level systems. Modern micro-PLCs offer the best price/performance ratio, whether built into new equipment or added to existing systems, to create industrial-grade automation and IIoT solutions.

This article was written by Bill Dehner, Technical Marketing Engineer at AutomationDirect. For more information, visit here .