vb与ab通过串口通讯AB系列的PLC一般都有专用的驱动程序用于实现PLC和计算机之间的通讯，如RSLINX就是专门用于做这项工作的，但使用RSLINX也具有一定的局限性，这里提供一个使用VB编程实现PLC和计算机之间的通讯程序，使用的协议是DF1，可以支持Micrologix、SLC500等系列的PLC-Vb with ab via a serial port communication ab series PLC usually have dedicated driver used to realize the communication between PLC and computer, such as RSLINX is dedicated to do the work, but using RSLINX also has certain limitation, here provide a vb programming to realize communication between PLC and computer program, the protocol used is DF1, can support Micrologix, SLC500 series PLC