In HID mode, the reader types data into the active field like a keyboard: it works without a driver, but the application cannot tell a scan from a keystroke. In USB-COM mode, the application reads a virtual serial port and knows where the data came from. Use HID by default and switch to USB-COM when the software vendor requires it.
Procedure
Ask the software vendor what it expects
The mode depends on the till software. If its documentation mentions a COM port, a baud rate or an OPOS class, keyboard mode will not be enough. If it mentions none of these, the software expects keyboard input.
Test in keyboard mode first
Most readers ship in keyboard wedge mode. Open a text editor, scan a known code, and confirm the characters appear followed by a line break. This test proves the unit itself works.
Switch to USB-COM only when required
Install the manufacturer’s driver first, then scan the programming barcode from the model’s manual to switch the reader to a virtual serial port. Do not do it “just in case”: every station will need the driver and must keep the same port number.
Pin down and record the port number
A virtual serial port can change number when the reader is plugged into a different USB socket. Assign the port in device manager, record it in the install sheet, and always use the same socket.
Check these before calling support
- The reader types correctly into a text editor, outside the till software.
- The software vendor has confirmed the expected mode in writing.
Useful terms
- Keyboard wedge (HID)
Keyboard wedge (HID) is the mode in which a reader presents itself as a keyboard: scanned characters are typed into the active field with no driver, but the application cannot tell where the input came from..
- USB-COM (virtual serial port)
USB-COM is a connection mode in which a USB device, through a driver, creates a virtual serial port.
- Prefix, suffix and terminator
Prefix and suffix are characters a reader adds before and after the scanned data.
Hardware involved
- SC310 (Barcode and card readers)