说明：  LabVIEW与PLC的OPC通信(三种方法)，通过此文档可以学习到LabView是如何和PLC进行通信，示例教程使用的PLC是西门子200.
(The OPC communication between LabVIEW and PLC (three methods). Through this document, you can learn how LabView communicates with PLC. The PLC used in the example tutorial is Siemens 200.)