There are generally two main types of PLC programming languages:
- Ladder Logic: This is the most common type of PLC programming language and is used to create control logic diagrams that resemble electrical ladder diagrams. Ladder logic is a graphical programming language that is easy to learn and understand, especially for people with a background in electrical or mechanical engineering.
- Function Block Diagram (FBD): This type of programming language is used to create diagrams that represent functions and their interactions. Function block diagrams are similar to ladder logic diagrams, but they are more compact and less cluttered.
- Sequential Function Chart (SFC): SFC programming is a graphical programming language similar to flowcharts, it’s used for creating programs in which the order of operations is critical. It’s used for creating sequential control logic, with clear and structured representation of the control system sequence.
- Structured Text (ST) : ST is a text-based programming language that is similar to the C programming language, it’s mostly used for implementing complex mathematical calculations, it’s suitable for engineers who are more comfortable with text-based programming.
- Instruction List (IL) : IL is a low-level, text-based programming language that is used to create programs by using a list of instructions. It is similar to assembly language, and it’s rarely used in modern PLC programming.
These are the main types of PLC programming languages, but some PLCs also support additional languages and may even allow the use of multiple programming languages in the same program. The choice of programming language depends on the specific requirements of the control system, and the skills and experience of the programmer.