COM port is a serial port, COM port ( cluster communication port ) that is, serial communication port.
Commonly used COM serial pins in industrial control machines generally have two interfaces, RS-232 and RS-485. In appearance, these two kinds of serial port are used 9-pin type.
COM ports are communication ports that can be used for many kinds of communication devices.
Hospital medical equipment control: hospital gastroscope, CT, chest x-ray machine and so on.
Supermarket charging related equipment: small ticket printers for supermarkets, swipe card machines, bar code robbers, etc..
Engineering production design control: PLC programmer .
Computer expansion peripheral equipment: such as printers, serial mouse, serial keyboard.
Expanded Information:
Serial port, COM port, TTL, RS-232, RS-485 Difference:
1. Serial port, COM port refers to the physical interface form (hardware). And TTL, RS-232, RS-485 refers to the level standard (electrical signal).?
2, when connecting the device, usually only GND RX TX. will not be connected to the Vcc or +3.3v power line, to avoid conflicts with the power supply on the target device.?
3, PL2303, CP2102 chip is a USB to TTL serial port chip, USB to extend the serial port (TTL level)
4, MAX232 chip is a TTL level and RS232 level of the special bi-directional converter chip, you can TTL to RS-232, but also RS-232 to TTL.?
5, TTL standard is a low level of 0, high level of 1 (+5V level). RS-232 standard is a positive level of 0, negative level of 1 (± 15V level).?
6. RS-485 is similar to RS-232, but uses differential signaling negative logic.
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