Hi I'm using an Uno and a GT-511C1R fingerprint sensor module in a project. For communicating, I went with this library from Josh Hawley:
When I run the blink example, for blinking the background led of the sensor, it runs fine but when I try the enroll example to add fingerprints I get nothing on the serial monitor.
And even when I run the blink code it only works if I plug in the sensor after uploading to the arduino board, it doesn't run if the sensor is hooked up already.
here's how the blink code looks:
/*
FPS_Enroll.ino - Library example for controlling the GT-511C3 Finger Print Scanner (FPS)
Created by Josh Hawley, July 23rd 2013
Licensed for non-commercial use, must include this license message
basically, Feel free to hack away at it, but just give me credit for my work =)
TLDR; Wil Wheaton's Law
This simple sketch turns the LED on and off similar to the Arduino blink sketch.
It is used to show that communications are working.
*/
#include "FPS_GT511C3.h"
#include "SoftwareSerial.h"
// Hardware setup - FPS connected to:
// digital pin 4(arduino rx, fps tx)
// digital pin 5(arduino tx - 560ohm resistor fps tx - 1000ohm resistor - ground)
// this brings the 5v tx line down to about 3.2v so we dont fry our fps
FPS_GT511C3 fps(4, 5);
void setup()
{
Serial.begin(9600);
fps.UseSerialDebug = true; // so you can see the messages in the serial debug screen
fps.Open();
}
void loop()
{
// FPS Blink LED Test
fps.SetLED(true); // turn on the LED inside the fps
delay(500);
fps.SetLED(false);// turn off the LED inside the fps
delay(200);
}
and here's the enroll:
/*
FPS_Enroll.ino - Library example for controlling the GT-511C3 Finger Print Scanner (FPS)
Created by Josh Hawley, July 23rd 2013
Licensed for non-commercial use, must include this license message
basically, Feel free to hack away at it, but just give me credit for my work =)
TLDR; Wil Wheaton's Law
*/
#include "FPS_GT511C3.h"
#include "SoftwareSerial.h"
// Hardware setup - FPS connected to:
// digital pin 4(arduino rx, fps tx)
// digital pin 5(arduino tx - 560ohm resistor fps tx - 1000ohm resistor - ground)
// this brings the 5v tx line down to about 3.2v so we dont fry our fps
FPS_GT511C3 fps(4, 5);
void setup()
{
Serial.begin(9600);
delay(100);
fps.Open();
fps.SetLED(true);
Enroll();
}
void Enroll()
{
// Enroll test
// find open enroll id
int enrollid = 0;
bool usedid = true;
while (usedid == true)
{
usedid = fps.CheckEnrolled(enrollid);
if (usedid==true) enrollid++;
}
fps.EnrollStart(enrollid);
// enroll
Serial.print("Press finger to Enroll #");
Serial.println(enrollid);
while(fps.IsPressFinger() == false) delay(100);
bool bret = fps.CaptureFinger(true);
int iret = 0;
if (bret != false)
{
Serial.println("Remove finger");
fps.Enroll1();
while(fps.IsPressFinger() == true) delay(100);
Serial.println("Press same finger again");
while(fps.IsPressFinger() == false) delay(100);
bret = fps.CaptureFinger(true);
if (bret != false)
{
Serial.println("Remove finger");
fps.Enroll2();
while(fps.IsPressFinger() == true) delay(100);
Serial.println("Press same finger yet again");
while(fps.IsPressFinger() == false) delay(100);
bret = fps.CaptureFinger(true);
if (bret != false)
{
Serial.println("Remove finger");
iret = fps.Enroll3();
if (iret == 0)
{
Serial.println("Enrolling Successfull");
}
else
{
Serial.print("Enrolling Failed with error code:");
Serial.println(iret);
}
}
else Serial.println("Failed to capture third finger");
}
else Serial.println("Failed to capture second finger");
}
else Serial.println("Failed to capture first finger");
}
void loop()
{
delay(100000);
}
Any help on this would be greatly appreciated 
Also I have included the data sheet which is a bit confusing to understand for me.