说明：  labview中用程序去产生一个触发事件是个难点，相关的介绍和例子并不多，本程序使用值属性信号结点改变的方法去产生一个事件，实现程序控制产生触发事件的功能，labview开发版本8.2。
(labview using the program to generate a trigger event is difficult, relevant examples of the introduction are not many,here we use the value change of the node attribute of the signal to generate an event, the realized the program control functions to generate trigger events, the version of labview development is 8.2 .)