Abstract: The communication between PC and PLC is realized under free port mode based on VB6.0. In the experiment, on the basis of the characteristics of PC and PLC communications and free port communication features, PC-PLC process and means of communication are studied. The combination of VB and the Windows API functions can gain the time of communications between PC and multi-PLC in different means of communication. The advantages and the disadvantages of different forms of communication in the communication time and the structure are compared, and implementation instances are presented to different communications occasions.

Key words: VB6.0, programmable controller, free port, communication

摘要： 介绍在VB6.0环境下实现PC机与PLC的自由口通信，根据PC机与PLC通信的基本特点以及自由口通信的特点，研究实验中PC机与多台PLC的通信流程以及通信方式。将VB和Windows下的API函数相结合编程得到不同通信方式下PC机与多台PLC之间的通信时间。比较了不同通信方式在通信时间和结构上的优缺点，给出了不同通信场合下的应用实例。

关键词: VB6.0环境, 可编程控制器, 自由口, 通信

CLC Number: 

• TP368.3