F7553 Microcontroller Polling Circuit

The F7553 microcontroller has to poll the on-line applications issued by each PC, that is, to realise the communication between the PC and the microcontroller.In realising the communication between the PC and the microcontroller, the standard serial bus communication interface RS-232C is usually used.RS-232C is the most widely used standard bus in asynchronous serial communication.The simplest connection between the PC and the microcontroller is the Zero Modulation Three-Wire Economy, which is the minimum line necessary for full-duplex communication. This is the least amount of wiring necessary for full-duplex communication.

The F7553PC is connected to the microcontroller and PLC through a standard 9-pole socket. The design of the microcontroller polling circuit by the CD4052 chip and MAX232 chip composition. CD4052 chip is a dual-channel, four-channel analogue multiplexer, a CD4052 chip can be achieved on four PC polling. MAX232 is the implementation of the RS-232C level conversion to TTL level of the level of the level of conversion of the special integrated chip.

Resource sharing circuit design is to achieve “multiple choice” and “one choice” function. That is, multiple PCs can communicate with the same PLC at different times, while a PC can communicate with multiple PLCs. This design uses an integrated circuit scheme with an RS-232C bus and a multi-bit data selector as the core. The integrated circuit is designed to share resources by designing a switching network circuit in the form of a row and column structure.The communication between the PC and PLC also uses the standard serial bus communication interface RS-232C, with the simplest three-wire connection, so this design selects the CD4053 chip as the data selector switch.The CD4053 chip is a three-way, two-channel analogue multiplexer.