PLC programming won’t change dramatically anytime soon, but new technologies are having an impact, explains Tim Hider, industry marketing manager for smart manufacturing and digital solutions at Mitsubishi Electric Automation. “While higher-level tools like Python and C# are gaining attention, IEC 61131-3 languages are unlikely to be fully replaced in the near future,” he says. “The integration of generative artificial intelligence (AI) into development tools is increasing the popularity of structured text (ST), as it is easier for AI to generate and interpret compared to more visual languages like ladder diagram (LD) or function block diagram (FBD). Additionally, open-source communities often provide well-tested Python snippets that can complement ST. However, the industrial nature of PLCs—designed to last for decades—means that IEC languages, which have also been industrialized, will remain relevant for a long time.”
Sara McGhee, product owner of Simatic AX at Siemens, does see a place for higher level languages in industry. “I know we have applications where we’re doing fast communication between the PLC and something running one of those high-level languages, whether it be an IPC or some other kind of computer,” she says. However, she doesn’t see standard PLC programming go away entirely. “I think PLCs are going to become more powerful and then maybe some other languages could be leveraged,” she predicts.
In the dawn of industrial artificial intelligence, text-based languages might also get a leg up. “It’s a lot easier to train a model on a text-based language, rather than a graphical one,” McGhee says. AI is also much better at deciphering what the structured text is programmed to do. “When we think of who’s servicing and maintaining these machines, if you weren’t the one to write the code, to be able to feed that into an AI model and have it kick out at least an idea of what is going on in that program is going to be huge,” she says.
Claudia Dürr, global marketing manager at Siemens, says even IEC languages are expected to evolve. “Structured text is already serving as a bridge between traditional control programming and modern software development practices,” she says. “In parallel, higher-level programming languages are increasingly being used alongside IEC 61131-3 languages, especially for tasks such as data analytics. Applications at the edge or in the cloud, as well as those involving simulation or digital twins, often benefit from the flexibility and power of higher-level languages. As a result, a hybrid approach is emerging—preserving the stability of proven PLC languages while leveraging modern software paradigms where appropriate.”
Aaron Dahlen, applications engineer at DigiKey, says any shift toward different languages lies in the close relationship between the PLC and the microcontroller. A microcontroller or microprocessor in a ruggedized protected environment is the core of a PLC. “Any shift away from the traditional PLC programming languages is a move toward the raw microcontroller or, in some systems, a move closer to the real-time operating system (RTOS) hooks running on top of a microprocessor,” Dahlen says.
The more real-time constraints that are added, the more complex the programming becomes, and industrial safety adds another layer. “For example, the programmer may stick with the tried-and-true PLC program scan—get inputs, run the user’s program, set outputs and then perform housekeeping. While this process is baked into ladder logic, it is not inherent in higher-level tools. As a result, the programmer must construct the responsive code or purchase intellectual property to coordinate the program. They effectively trade the well-known safety of the IEC 61131-3 environment for a different abstraction layer that performs the same basic operation,” Dahlen says.
With the wide variety of equipment used across industrial automation, some applications may prefer higher-level languages. Some users may also prefer non-native PLC software, such as a PLC capable of running MatLab. “This unique configuration is supported by the Raspberry Pi compute class of PLCs, such as the Kunbus,” he says.
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Casey Taylor, software product manager at Beckhoff Automation, says tools like source-control, usually Git, editor availability and more recently generative AI are also influencing the increasing support for text-based languages. Programmers that can bridge the gap between controls programming and other emerging technology could be a competitive edge in industrial automation. “When an engineer needs to work in both areas, there is a clear benefit when the tools are similar,” says Taylor. “It can also be beneficial when they can use the same source control, editor, compiler and other tools. As some automation software platforms have grown to encompass commonly used computer science standards, programmers should gravitate toward solutions that continue to expand and directly incorporate these new technologies. The goal should be to provide as many high-value programming tools as possible and widen the pool of engineering talent that machine builders and system integrators can leverage.”
While higher-level languages are being used more in programming for machine control, Taylor doesn’t see IEC languages being replaced completely. “Some components of a system can be and often are written in these higher-level languages, but each language has inherent strengths and weaknesses,” he says. “The IEC languages, particularly structured text, give you access to the many strengths of object-oriented programming while naturally avoiding things such as dynamic memory allocation, which should be used less often or at least carefully in a machine that needs to be deterministic and respond quickly.”
Imran Mohamed, motion control application engineer at Yaskawa America, agrees that modern PLCs are advancing, and higher-level languages will play a role in the future. “Modern PLCs are increasingly being designed to support new technologies by offering higher-level language support, such as Python and C++, alongside traditional IEC 61131-3 languages,” he says. “They also include advanced communication protocols like OPC UA, MQTT and REST APIs, which are well-suited for connectivity to cloud platforms and third-party applications.”
