分析软PLC运行系统基本逻辑指令的实现方法和顺序执行的过程。提出了采用回调函数加循环的方法来实现指令的运行。采用回调函数不仅可以实现指令的顺序执行,还可以执行子程序调用指令及循环指令等,而且其扩展性比较强,可以根据需要随时增加指令函数,易于移植到其它数控系统中。 Analysis of soft PLC operating system basic logic instructions to achieve the method and sequence of the implementation process. Proposed a callback function plus the method of circulation to achieve the operation of the instruction. The use of callback function not only can achieve the order of execution, you can also perform subroutine call instructions and loop instructions, and its scalability is relatively strong, you can at any time increase the command function, easy to transplant to other CNC system.