PLCs are evolving and continue to be the best option for a variety of industrial automation applications. Greater programming flexibility and ease, scalability, more memory, smaller sizes, very high-speed (Gigabit) Ethernet, and built-in wireless are among evolving programmable logic controller features.
If you use PLCs or are thinking of doing so, you may consider them to be a mature technology with little room for improvement as they’ve been around for nearly 50 years. But like their close counterparts in the world of consumer electronics, significant improvements continue with no end in sight, promising faster, smaller, and lower cost solutions.
The PLC’s hardened embedded processor, running a real-time proprietary operating system, has proven to be a mainstay of the industrial automation world, fighting off all challengers to its supremacy. Microsoft Windows-based open systems have made inroads but lag behind PLCs, a trend expected to continue as the PLC with its purpose-built hardware, specially designed software, and one-supplier support model remains a solid choice for many industrial control applications.
From the beginning, when the PLC was typically replacing scores if not hundreds of relays and timers, there’s been a push to decrease automation system size and to simplify support and maintenance. Over the years the relay panels have been replaced with smaller rack-based PLCs (Figure 1), or smaller yet PLCs with remote I/O. In terms of software, ladder logic programming initially mimicked automation systems based on relays and timers, and continues to be the most widely used PLC programming language. But other options have emerged—specifically, the IEC 61131-3 suite of PLC programming options.
In the future, PLCs will continue to evolve while adapting technology improvements in hardware, communications, and software. Part of the evolution will include merging of PLC and programmable automation controller (PAC) functionality, along with advancements to span communications from the plant floor to the top floor.
[A PAC is generally recognized as a hardened modular industrial controller that uses a PC-based processor and allows programming options beyond the IEC 61131-3 languages. Industrial PC or IPC is another term often used interchangeably with PAC.]