Sometimes it may be necessary to connect more than one GRE USB Scanner Interface Cable (P/N 30-3290) to your computer at the same time. In order to do this, it may be necessary to assign unique USB Serial Numbers to each cable that you wish to connect to the PC, such that the PC is able to recognize each cable individually.
Please follow these steps to accomplish this:
1. Download and install MPROG 3.0a from FTDI (http://www.ftdichip.com/Resources/Utilities.htm#MProg)
2. Make sure exactly one cable is plugged into the PC
3. In MPROG, from the Tools menu, select Read and Parse
4. Check the "Use Fixed Serial Number" box
5. Change the serial number (i.e., change 0412 to 0413)
6. Make sure the "Only Program Blank Devices" box is NOT checked
7. Save the file (File>Save As). This is VERY important, as you cannot program the chip until the file is saved.
8. Program the device (Device>Program)
9. Exit MPROG
When you plug in a second cable (one with a different serial number, or one that has not had the USB Serial Number reprogrammed with MPROG), Windows will recognize it as a new device and install the drivers for it.
If you find that MPROG is not able to communicate with the cable, download and install the V2XX drivers from FTDI (http://www.ftdichip.com/Drivers/D2XX.htm). MPROG requires the D2XX drivers in order to work properly. The drivers on the radio CD are the VCP drivers. In most cases MPROG appears to install its own D2XX.DLL file so this may not be a problem. 
