As S7-300/400 series PLC(Programmable Logic Controller) is node controller based on field bus net,it is difficult to develop the communication software on Lab Windows/CVI platform for its privacy of communication protocol.

• 西门子S7-300/400系列可编程逻辑控制器(PLC)是基于现场总线网络的节点控制器,其通信协议不开放增加了在Lab Windows/CVI等平台上开发通信驱动软件的难度。