Nine pin serial port, namely RS-232 interface, is one of the communication interfaces on personal computer. It is an asynchronous transmission standard interface formulated by Electronic Industries Association (EIA). Generally, RS-232 interfaces appear in the form of 9 pins (DB-9) or 25 pins (db-25). Generally, there are two groups of RS-232 interfaces on personal computers, which are called COM1 and com2 respectively.
9-pin RS232 serial port wiring diagram
Serial interface definition
The communication between inspection instrument and microcomputer is mainly based on RS232C standard interface, and the wiring method of serial port also has certain standards. Let’s have a look.
Standard connection method
1. 9 to 9 (including 9 for 9 holes, 9 for 9 holes, 9 for 9 pins):
Note: the following holes and pins refer to the serial ports at both ends of the serial port line, but 2 and 3 may not be exchanged
2. 9 to 25 (including 9 holes to 25 holes, 9 holes to 25 needles)
2 —————– 3 (Note: 2 and 3 may not be exchanged)
Analysis of RS232 serial communication protocol
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