ADH Technology, the company that sells the GT-511C3 fingerprint scanner provide SDK software that includes a demo application for running on a PC. The demo software allows the scanner to be used to enrol fingerprints, each with a unique ID and then identify enrolled fingerprints when a finger is placed on the scanner later. The GT-511C3 fingerprint scanner demo software also includes several other functions that allow fingerprints to be deleted, display number of registered fingerprints, etc.
A USB to TTL level device is normally needed to connect the fingerprint scanner to a Windows PC to use the demo application.
Connecting the GT-511C3 Fingerprint Scanner to a PC using an Arduino
The article on interfacing the GT-511C3 to a PC running the demo software provides a quick hack that uses an Arduino Uno as a USB to TTL converter. The Arduino Uno uses a software serial port to connect to the fingerprint scanner because the only hardware serial port on the Uno is connected to the USB chip which is used as the interface to the PC USB port.
Serial data is relayed between the fingerprint scanner and demo software on the PC by a sketch running on the Arduino. The image below shows the demo application and interface to the scanner. Also see the full article that explains the hardware connections and software needed for the project.