SCSI (small computer standard interface)
This interface the largest number of connected devices to 8, usually the largest transmission speed is 40m/s, faster, generally connected to high-speed equipment. SCSI device installation is more complex, on the PC on the general need to add a SCSI card, easy to produce hardware conflicts, but powerful.
EPP (Enhanced Parallel interface)
An enhanced two-way parallel transmission interface with a maximum transmission speed of 1. 5Mbps. The advantage is that there is no need to use other cards in the PC, unlimited number of connections (as long as you have enough ports), the installation and operation of equipment easy. The disadvantage is that the speed is slower than SCSI. This interface replaces the SCSI interface with low performance requirements at the lower and middle end due to easy installation and ease of use.
USB (Universal Serial Bus Interface)
Up to 127 peripherals can be connected, now the USB1.1 standard Maximum transmission speed of 12Mbps, and has a secondary channel to transmit low-speed data. In the future, if there is a USB2.0 standard barcode scanner speed may be extended to 480m/s. Hot-swappable function, Plug and play. The barcode scanner for this interface is becoming popular with the establishment and promotion of the USB standard under Intel's push.
PS2 (Keyboard interface)
and USB usage is similar, need a smart head conversion, the general purchase of the scan gun will be accompanied by the. There are still a lot of companies using the PS2 interface.