What are the interfaces of the barcode scanner

According to different requirements, the barcode scanner ports on the market can be roughly divided into serial ports, keyboard ports, and USBs. The following briefly explains what these three interfaces are and the differences between them.
Keyboard interface and serial port interface, these two interfaces have advantages and disadvantages, such as the need for an external power supply, which is relatively troublesome. And the appearance is not very beautiful, but the external power supply has a certain guarantee on the voltage. If some scanners have voltage requirements, this interface can be used.
The power supply of the serial port barcode scanner needs to be connected externally, and the scanning length can reach 60 meters according to the RS232 standard. The application range is very wide and the input speed is fast.
Keyboard port, no external power supply is required, and the scanning distance is generally 1.5 to 5 meters. Input speed is relatively slow.
The USB interface also does not require an external power supply, and the scanning distance is 1.5 to 5 meters. It is widely used, and most of the interfaces on the market use this interface. Type faster.
The USB virtual serial port belongs to the category of USB communication equipment. It is necessary to pass through the USB bus at the physical layer, and then use the virtual serial port to provide a physical serial port for the host, and provide an IN endpoint for bulk transfer and an OUT endpoint for bulk transfer in the internal USB controller of the system for data reception. and send. Simulate the RX and TX lines of the serial port. In addition, the USB controller also needs to provide an interrupt IN endpoint to send the current serial port status. Realize the control of the serial port transmission.
The data of the serial device is collected by the serial port of the system. The encapsulation of the USB package is completed in the chip. Then use the USB bus to upload to the switchboard. It is processed by the corresponding serial port application program. For users, what they see is data collection and transmission based on export, but what is realized is data transmission based on USB protocol packets.