How to connect a Gps device to PC

I have A Starcom System Helios GPS tracker. It was not in use for 4 years.
Now i want to use it on Orange GPS for free tracking.
For this I have to change device server and port. There is RS232 three wires in device which is used to communicate with pc using RS232 to USB converter cable. I bought a RS232 to USB cable and connect three wires RX, TX, Ground from gps device to cable. my PC can detect the cable in device manager but GPS application can not detect my device. How do i connect my GPS to PC.
System Windows 8.1 64 Bit
Gps device- Helios Adv 1.0

 

I don't know what parameter are used by tracker.... What should be these value for a tracker?

 

Please read the page no. 33 of the manual of the tracker.
http://www.starcomgpsglobal.com/wp-c...nual-Guide.pdf
I'm using RS232 Cable for connect to PC.
The installer application is not detecting the tracker. see screenshot.

 

The baud rate is set to 115200 by default. There is only three wires from tracker- GND, RX and TX.
I connected RX to number 2 pin , TX to number 3 pin and GND to number 5 pin of RS232 cable.
I also tried replacing number 2 and 3 pin by TX and RX respectively but nothing happens. see page number 83 for wire lable.
see screenshot.