Features and writing steps of PLC instruction table programming language

PLC instruction table programming language is a low-level programming language that uses symbols and instructions to control the operation of the program. It is mainly used to write PLC programs to achieve industrial automation control. The language contains a set of instructions, such as logic, comparison, calculation, etc., and is combined into programs according to specific rules. Due to the poor readability and maintainability of the instruction table language, it has now been replaced by higher-level programming languages, such as structured text language, flow charts, and function blocks.

The basic unit of the PLC instruction table programming language is the instruction. Each PLC instruction table statement consists of three parts: instruction code, operand, and comment. The instruction code is used to determine the type of operation of the instruction, the operand specifies the address and type of the operation object, and the comment is used to explain the function of the instruction. The instruction statement is the basic unit of the PLC program. According to the different functions of the instructions and the different types of operation objects, the PLC instruction table instructions can be divided into multiple types such as input and output instructions, logic control instructions, arithmetic calculation instructions, timer and counter instructions, etc.

The characteristics of PLC instruction table programming language are as follows:

1. Sequential execution: PLC instruction table programming language is a sequential execution language. The program is executed in the specified order without jump statements and loop statements.

2. Low level: PLC instruction table programming language does not have a high level of abstraction and complex grammatical structure like high-level languages. Its instruction table is written directly for the specific operation of the equipment.

3. Strong capabilities: PLC instruction table programming language can perform many real-time control operations, such as calculation, control, motion control, etc.

4. Strong flexibility: PLC instruction table programming language can be programmed according to different needs.

5. Low readability: The syntax of the PLC instruction table programming language is relatively simple, often using abbreviations, and has poor readability.

6. Difficult to debug: Debugging of the PLC instruction table programming language requires a deep understanding of the specific operating principles of the equipment and needs to be verified in actual operation.

The PLC instruction table programming language can be written using the following steps:

1. Confirm the specific specifications and syntax of PLC model and PLC instruction table programming language.

2. Define the PLC addresses of input and output and map them to the actual devices.

3. Design a program flow chart or state diagram based on actual control requirements, and write the PLC instruction table programming language corresponding to each step of the operation into code.

4. Debug and test the program to ensure its correctness and stability.

5. In actual application, real-time monitoring and adjustment procedures are carried out as needed.

The specific way to write the PLC instruction table programming language varies depending on the PLC manufacturer and different PLC models. It is recommended to refer to the PLC device's documentation before writing, or refer to the PLC programming textbook for learning. At the same time, during the writing process, it is necessary to make detailed comments on each line of code to facilitate the reconstruction and maintenance of the program.