Open PLC in compliance with IEC standards

IEC1131-3 is the standard developed by IEC for industrial automation programming. It is developed by absorbing the programming language styles of different manufacturers and adapting to the requirements of future software technology development. It is independent of any company and is suitable for use by programmers in different fields and programs. Since its release, it has been recognized by all top PLC manufacturers, and all manufacturers have also tried to move closer to IEC standards.

After more than 30 years of development, the domestic CNC system has greatly improved both functions and performance, and the gap with well-known foreign CNC manufacturers has also narrowed. However, due to technical reasons, an important part of the CNC system - built-in PLC compared to foreign systems still has a big gap, mainly in: many low-grade CNC systems do not support PLC, high-end CNC is mostly using a dedicated PLC language, the user Use is very inconvenient, such as C language. Beijing Aerospace Numerical Control has used the IL language to write PLC logic in the past. Because it is an instruction method, it is suitable for programmers to design programs and is not suitable for machine tool electrical engineers, thus causing a lot of inconvenience to machine tool manufacturers or users.

In view of the above situation, Beijing Aerospace Numerical Control Co., Ltd. cooperated with well-known professional PLC manufacturers in China and developed the CNC editing and compiling software of the CNC system that complies with the International Electrotechnical Commission's IEC1131-3 specification, and applied it to the CNC system of Beijing Aerospace Numerical Control. This PLC edits and compiles the software to conform to IEC1131-3 norm, completely independent development, and can run WIN98, WIN2000, WINXP and other operating systems, simple and easy to learn.

Aerospace CNC PLC editing and compiling software has the following features:

(1) Conforms to IEC1131-3 standard.

(2) Supports two standard languages, IL (instruction list) and LD (ladder).

(3) Rich instruction set, built-in standard functions, function blocks and some special application instructions defined by IEC1131-3.

(4) Dedicated instructions and function blocks suitable for numerical control applications.

(5) Support user-defined function blocks (subroutine functions).

(6) Perfect online functions, including: download, upload, online monitoring and other functions.

(7) Perfect shortcut keys are convenient for users.

(8) It has the function of engineering information to facilitate the maintenance of PLC user programs and system maintenance.

Beijing Aerospace Numerical Control PLC memory area is described in the table below.

Simple introduction

At present, Aerospace CNC PLC editing and compiling software supports both LD and IL programming languages. Its style is shown in Fig. 1 and Fig. 2: Under the main screen, it contains menu, toolbar, status bar, project manager, instruction set, user work area and information output area.

Menu: Contains all the PLC software commands.

Toolbar: Contains some commands frequently used by users in PLC software.

Status bar: Provides current software status information and operation command prompts.

Project Manager: Uses a tree structure to display the organizational structure of the entire project.

User workspace: Variable table, editor window, etc.

Instruction Set: Lists all instructions, function blocks, and user subroutines of the Aerospace Numerical Control PLC in a tree. This instruction set is further divided into LD instruction set and IL instruction set.

Information output area: Displays the software output prompt information, including compiling information, search results and so on. The instruction set describes the aerospace numerical control PLC supporting the basic instructions of the IEC61131-3 standard and most of its functions/function blocks. The programming style conforms to the requirements of the IEC61131-3 standard. According to the actual requirements of the PLC of the machine tool numerical control system, the standard instructions are appropriately expanded. Fully meet the CNC requirements of machine tools.

Aerospace numerical control PLC instructions are roughly divided into the following categories: bit instructions, assignment instructions, comparison instructions, logic operation instructions, shift instructions, mathematical operation instructions, program control instructions, timers, counters, subroutines, and numerically-controlled special instructions.

Bit instructions include: normally open contacts, normally closed contacts, common coils, reset coils, set coils, rising edge detection, falling edge detection, and so on.

Assignment instructions include: MOVE, BLKMOVE, and so on.

The comparison instructions include: greater than, greater than or equal to, equal to, less than, less than or equal to, not equal to the instruction.

Logical operation instructions include: bit-by-bit inversion, bitwise AND, bitwise AND, bitwise OR, bitwise OR NOT, bitwise XOR and other instructions.

The shift instructions include: left shift, right shift, loop left shift, loop right shift instruction.

Mathematical operation instructions include: addition, subtraction, multiplication, division, remainder, plus 1, minus 1, and other instructions.

Program control instructions include: unconditional jumps, conditional jumps, conditional reverse jumps, return instructions, and so on.

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