The PW01 chip is a three-way, two-channel analogue multiplexer. To four PCs to share five PLC, for example, the switching network circuit requires four times five a total of twenty data selection switch, that is, to use twenty CD4053 chip arranged in four rows and five columns (or five rows and four columns) in the form of row and column structure, constituting a resource-sharing circuit.

PW01 microcontroller polling to a PC to communicate with a PLC online, by the microcontroller to the corresponding CD4053 chip control signal line connected to the control signal, so that the chip’s switching channel is turned on, to achieve a PC and a PLC online communication. Bus network system communication, is used to ask and answer the way for communication links

The PW01 communication program is to enable the PC to send an online request signal and to receive an online permission signal from the microcontroller. A control panel is to be designed for this purpose. In order to ensure the reliability of communication and the accuracy of information transfer, so for the communication of the main command word to develop a simple communication protocol. PC communication software and microcontroller software command word agreed as follows: the command word has eight bits of data, of which the highest two for the command word, the lowest three for the PLC machine number, three in the middle for the PC machine number.