除特殊情况外，PAC系统用户自定义程序的执行遵循IEC 61131-3标准定义一个函数块要在编程软件中创建一-个函数块，首先在程序块文件夹中创建一个LD或ST块。在块的特性(Properties)栏中，选择函数块。要为函数块定义实例数据，选择块属性的参数栏。输入输出参数定义方法与参数化模块的定义方式相同。下面的例子中，定义了3个内部成员变量:temp,speed和modelno.

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