There are 3 kinds of prevalent Barcode Scanner interface, which is RS232, USB and Keyboard wedge, here are the details of these 3 interfaces.

RS232 (serial) Output

RS232 interface also called nine pin serial port because it has nine pins ,it is the most use interface before USB interface get popular.

With a RS232 output scanner, you would also need to either develop your application software to open and read in data from the RS232 serial port directly or use a software interface like the TALtech WinWedge software products. The main advantage of the RS232 output option is that you can develop your application so that it does not matter where the cursor is. When you scan a barcode, the data always goes to the correct place in your application program because the data from the scanner is going directly into the application program and is not going through the keyboard port. The RS232 interface requires a little more work up front because you either need to develop your software to work directly with the RS232 port (or configure the WinWedge software to act as the interface between the RS232 port and your application software) however the advantage to this approach is that you end up with a much more robust application that does not rely on the user making sure that the cursor is in the correct place in your application program before scanning a barcode. If you need to create a barcode application that is completely "idiot proof", then the RS232 interface option is by far the best choice.

The RS232 output option also makes it possible to manipulate the data that you receive from the barcode scanner before writing the data to the application program where you want the data to go. For example, if you want to parse the barcode data or add a date or time stamp to it, the RS232 serial output option would allow you to do this.

One issue that you may run into is that some newer desktop PCs and almost all new laptop computers do not come with any RS232 serial ports. The problem is easily solved by purchasing an "Add-on" RS232 serial adapter for the PC. There are even add-on RS232 serial adapters available the connect to a USB port on a PC. A single port add-on serial adapter that connects to a USB port should cost no more than $30 and you can find them at any computer or office supply store.

USB Interface

USB is the norm for connection to a PC.  USB is the physical connection, with multiple communication protocol options.  USB ports provide sufficient power for most scanners and the scanner itself can emulate the communications protocols I just summarized, plus a third protocol.

USB Keyboard Emulation.  This is the default for most USB scanners.  It functions identically to the Keyboard Wedge Interface described above.

COM Port Emulation.  Using a software driver, USB scanners can be assigned a virtual COM Port.  This usually gives the user more flexibility in managing multiple devices using COM Port communication, but keep in mind that the software and hardware must be set to communicate on the same COM Port.

HID Barcode Scanner.  HID stands for Human Interface Device.  There are numerous devices which communicate in USB HID mode, including keyboards, mice and other input devices.  An HID keyboard (which is what USB Keyboard Emulation is) only allows one-way communication from the keyboard to the computer.  HID Barcode Scanner offers bi-directional communication, which opens up the potential uses by your software application.

Keyboard Wedge Output

The "Keyboard Wedge" output option is the most common option. To interface a keyboard wedge barcode scanner to a PC, you would disconnect the keyboard from the keyboard port on the PC, plug the barcode scanner directly into the keyboard port and then connect your keyboard to a small "jumper cable" on the end of the barcode scanner cable (so that you do not lose the functionality of your keyboard). In other words, you are connecting the barcode scanner in the line between your keyboard and you PC. (One benefit of this is that the barcode scanner gets its power from the keyboard port so you do not need to connect any type of power supply to the scanner.)

When you scan a barcode with a keyboard wedge scanner, the data that is encoded in the barcode goes into the PC through the keyboard port so that it appears to whatever software is running in the PC as if it were being typed in on the keyboard. (i.e. The barcode scanner behaves exactly like a second keyboard connected to the PC.)

With a keyboard wedge scanner, you do not need any additional software. You simply plug the scanner in and start scanning barcodes. The keyboard wedge interface is extremely simple and in most situations, you do not need to make any changes to the software that you will be scanning the barcode data into.

The main advantage of the keyboard wedge interface is that it works just like a keyboard. You put the cursor where you want the barcode data to go and then scan the barcode and the data pops in just as if you typed it on the keyboard. The disadvantage of the keyboard wedge interface is that it works just like a keyboard. If the cursor is not in the correct input field in the correct application program, then, when you scan a barcode, the data still gets entered into the PC as if it is being typed in on the keyboard. If the cursor is not in the right place or if the application that you want the barcode data to go into does not have the input focus, the data goes to the wrong place or possibly the wrong application program. Also, if you need to modify the data in any way before it goes into the application program running in the PC, you cannot do this. For example, suppose that you need to parse the barcode data so that separate parts of the data goes to different input fields or if you want to add a date or time stamp to the barcode data, it is not possible with a keyboard wedge barcode scanner.

For now most devices has usb port, and it is very fast to upload data to host, make it getting more and more popular. Our products of barcode scanner most support above interfaces, different devices and apps need different interface, to choose the suitable barcode scanner interface, please contact us to get professional suggestions.