Over the decades the communication between operator and machine has been the driving force behind efficiency and safety. Without this crucial communication, manufacturers would come across a plethora of wasted cost as well as dangers situations. Giving precise commands and execute them instantaneously is crucial to making sure any automation facility operates at its best. PLC languages are very important, for their ability to allow the operator to communicate complex tasks to machines. Not only that, but their ability to automate tasks takes allows the operator to focus on other important tasks.
There exist a multitude of challenges that come with performing these tasks with a diverse scenario of situations. Because of this, there are multiple coding languages that become involved when discussing PLCs.

Traditional PLC Languages

Ladder Logic (LD)

The OG of programmable languages, Ladder Logic was created by Modicon Corporation in the 1970s for their PLCs. The industry needed a programming language that could effectively mimic the wiring diagrams used in relay-based control systems. These systems were prevalent in industrial settings for controlling machinery and processes.

Ladder Logic’s graphical representation consists of horizontal lines (rungs) with vertical lines (rung rails) that represent control circuits. This is much like the rungs on a ladder. The visual resemblance to electrical wiring diagrams made it intuitive for personnel accustomed to working with relay logic. This eased the transition from hard-wired systems to programmable control.

Today, Ladder Logic’s simplicity and visual nature makes it a fundamental programming language in industrial automation.

Structured Text (ST)

For intricate algorithms and mathematical operations within industrial automation, Structured Text emerges as a prevalent choice. Resembling high-level languages like Pascal or C, ST allows engineers to articulate complex control strategies with ease. Its readability and versatility make it an ideal choice for implementing algorithms in industrial settings.

Function Block Diagram (FBD)

Employing a graphical approach, Function Block Diagrams break down complex systems into interconnected blocks. This visual representation simplifies the design and maintenance of systems, facilitating easy comprehension and troubleshooting in industrial environments.

Sequential Function Chart (SFC)

In scenarios requiring a structured approach to depict sequential operations, Sequential Function Charts come into play. This graphical language represents a sequence of operations in a state-based manner. It offers a clear depiction of complex processes and control flow.

Instruction List (IL)

Instruction List, akin to assembly language, operates at a low level using mnemonic codes. Ideal for detailed control in PLCs, IL enables engineers to create precise instructions for control systems, making it indispensable for fine-tuning operations.

C/C++

C++ became integrated into industrial automation and PLC during the late 90s and early 00’s. However, C++ was slow to be integrated due to lack of optimization to work in a real time setting. Another factor for its slow adoptions, was compatibility. At the time languages like Ladder Logic and Function Block Diagram were more widely used in industry. However, C++ made up for this early setback with its ability to compute complex tasks.

Future Languages

Python and Java

The advent of Python and Java in industrial automation signifies a shift toward versatility and broader system integration. Python’s ease of use, coupled with its capabilities in data analysis, scripting, and interfacing with various systems, has positioned it as an increasingly popular choice. Java, with its platform independence and object-oriented approach, finds a place in larger-scale industrial applications.

The choice of programming language in industrial automation hinges on a multitude of factors, including system requirements, hardware compatibility, existing infrastructure, and the expertise of the programming team. Each language brings its own strengths to the table, catering to different facets of control and automation.

Conclusion

As industries evolve and technology advances, the landscape of programming languages in industrial automation continues to expand. Understanding and leveraging these languages empower engineers to build robust, efficient, and adaptive systems that drive the future of manufacturing and industrial processes.