PLC programming language is the language used to write PLC programs in the field of industrial control, aiming to realize the automated control and monitoring of industrial equipment and production processes.PLC programming language contains multiple language types, such as graphical programming language, textual programming language, structured programming language, etc., which can be selected and combined according to different application scenarios and programming needs.
PLC programming language expression mainly has the following types:
1. ladder diagram (ladder diagram): is the most commonly used PLC programming language expression, similar to the form of circuit diagrams, used to describe the switching, counting and other logic control.
2. function block diagram (function block diagram): is based on the function block programming language, used to describe the logical relationship between inputs and outputs. 3. structured text (structured text).
3. structured text (structured text): similar to high-level language programming, used to describe the control process and algorithms. 4. instruction list (instruction list).
4. instruction list (instruction list): similar to the expression of assembly language, used to describe the specific instructions and operations.
5. sequential function chart (sequential function chart): used to describe the control process and state transfer chart form.
The above PLC programming language expressions have different application scenarios and advantages and disadvantages, and need to be selected according to the specific control requirements and programmer's proficiency.
Conversion between PLC programming languages may result in changes in language structure and syntax. The following are several methods of conversion between PLC programming languages:
1. Ladder Diagram (LAD) to Structured Text (ST) conversion
Conversion between LAD and ST may result in different code and requires attention to the structure and syntax of the language.
For example, LAD is programmed using electrical symbols, whereas ST is programmed using almost C-like expressions. Therefore, symbol mapping may be required for conversion.
2. Structured Text (ST) to Function Block Diagram (FBD) conversion
Conversion between ST and FBD needs to take into account the differences in language structure, operators, parameters, etc.
For example, ST is programmed using raw C statements, while FBD uses graphical symbols. For simple tasks, ST may be more clear and concise, while FBD is more suitable for data flow control tasks.
3. Instruction List (IL) to Structured Text (ST) conversion
Conversion between IL and ST needs to take into account differences in language structure and syntax.
For example, IL uses a concise instruction format, while ST uses a C-like expression format. Therefore, the conversion may involve syntax conversion and instruction mapping.
4. Function Block Diagram (FBD) to Ladder Diagram (LAD) conversion
Conversion between FBD and LAD may be complicated by differences in language structure and graphical representation.
For example, FBD uses graphical symbols while LAD uses electrical symbols. Therefore, symbol mapping may be required when converting between the two languages.
In summary, conversion between PLC programming languages requires consideration of differences in language structure, syntax, operators, etc. Conversion needs to be handled with care to ensure the correctness and readability of the code.