Problem reading data from an USB device

[makTSPL]

Dear All,
I am developing an application in C#. This application communicates with Garmin Forerunner device. I have developed a demo for it, which shows Device software version. but I am not able to get Device history Data. What should I pass for getting history data.

Below is the code sample which I am using for fetching device information:

// Product data
byte[] theProductPacke t = new byte[] { 20, 0, 0, 0, 254, 0, 0, 0, 0, 0, 0, 0 };

byte[] thePacket = new byte[] { };

// For initializing device
initDevice();

//Checking for device availability
if (gHandle.ToInt3 2() == 0)
{
return "No Device Found";
}

// Sending Packet for starting asession
SendPackets(the ProductPacket);

// Infinite loop for Data retreival
for (; ; )
{
// Getting one by one Packets
thePacket = GetPackets2();
if (Convert.ToInt3 2(thePacket.Get Value(0).ToStri ng()) == 20 && Convert.ToInt32 (thePacket.GetV alue(4).ToStrin g()) == 255)
{
break;
}
}

string Data = System.Text.ASC IIEncoding.ASCI I.GetString(the Packet, 4, thePacket.Lengt h - 4);

bool bSuccess = CloseHandle(gHa ndle);


I am sure that I have to change following:
// Product data
byte[] theProductPacke t = new byte[] { 20, 0, 0, 0, 254, 0, 0, 0, 0, 0, 0, 0 };

I am not asking for providing code, but if anyone can post approach for it then it will be highly appreciated.