Top PLCs for process control

Siemens SIMATIC S7

The Siemens‘ SIMATIC S7 has been a leading choice in the industry for 30 years, known for its robustness and reliability.

Some of its strengths include excellent performance, a high level of modularity and scalability, and broad compatibility with various systems using standard industrial ethernet communication protocols, including OPC-UA.

On the downside, an S7 system can be costly and moderately complex to set up and program.

Allen-Bradley ControlLogix

Allen-Bradley’s ControlLogix is renowned for its user-friendly programming and robust performance.

The ControlLogix is the latest evolution of the first Allen-Bradley PLCs which came to market 50 years ago. ControlLogix is easy to program, reliable in demanding environments, and provides a wide array of I/O interfaces.

ControlLogix, however, generally has a higher processor cost than other systems, and messaging between processors can be challenging.

Mitsubishi MELSEC

Mitsubishi’s MELSEC series is a cost-effective PLC option, ideal for small to mid-sized applications.

It is affordable and reliable. Its main limitation is its limited scalability as compared to other high-end competitors. Also, non-Mitsubishi communication protocols can be difficult to integrate.

Schneider Electric Modicon

Modicon by Schneider Electric is known for its versatility and strong integration capabilities. The first Modicon PLCs came on the market over 50 years ago.

Modicon is versatile and scalable and is easily integrated with other systems. Its biggest weakness is its moderate performance capabilities as compared to other top-tier PLCs.

As you can see, no PLC is perfect against all the evaluation criteria I discussed earlier, and it really comes down to which system can provide the features and functionality you need at a price you can afford.