This USB HOST module provides TTL pins Tx/Rx to connect any USB BARCODE SCANNER with Arduino
To test any barcode scanner you can connect the scanner to USB port of PC & Open NOTEPAD or Microsoft WORDScan any barcode to see the code printed on notepad window.
As you connect BARCODE SCANNER to PC it is considered as HID device (like mouse or keyboard) and anyresult from device will be printed on Notepad
For connecting the scanner with Arduino you need an USB HOST Module.RXD of host connected to Tx of ArduinoTXD of host connected to Rx of ArduinoPower to scanner taken from Arduino 5v pinGnd to GndWhile uploading code , remove connections at Rx/Tx pins.After upload successful connect back the pins.
 
3 LED s on board
Green  power led
Red  detect led - normally ON , when scanner connected it goes OFF
Blue led - Data Led