The communication between the PC and PLC based on VB6.0 in the ESP

A communication systerm of the ESP are designed detailedly. The PLC is known for its reliability, flexibility, and stability, and the FX_2N-PLCs are used. The hardwares needed by the communication, including FX-485PC-IF, RS-232C, RS-485 and 485ADP, are also introduced. Thus the design of the hardware connection is realized. What´s more, the communication program is discussed based on the serial communication protocol. In actual applications, the ESP based on the above design is really simple and convenient operation. This design can be well applied in practicality of ESP.