Pratheek,
so i understand that you have some kind of PCB with that circuit mounted on it. Is that custom made? Or is it some kind of standard PCI device from a well-known vendor?
Regarding the answer, the solution is very different.
In the second case, you should look for some drivers for the device. Many vendors provide an LV API, if not, you have to write the VIs yourself by calling the driver DLL.
In the first case, you have to figure out how to interface to the circuit. It should have some kind of standard interface (e.g. USB) running a custom protocol. If you know that protocol, you can wrap your own API functions.
Norbert