Your browser does not allow scripts
Please click here to view a static table of contents without scripts
Ignore Hardware Serial Number
Return to Introduction  Previous page  Next page
If devices have the same vendor ID and product ID but different serial numbers, the system will normally treat them as different devices. This causes the drivers to be installed for each device and create registry entries for each device.

It is possible to override this behaviour to make the system ignore a device's serial number and treat all devices with matching VID and PID connected to the same USB port as if they were the same device. This is achieved by adding a REG_BINARY value called
IgnoreHWSerNum
to the registry and setting it to 01.

This value is held in the registry key located at:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\UsbFlags\IgnoreHWSerNum{Device VID, PID and interface}


For a default FTDI device ID (VID 0x0403, PID 0x6001), add the following registry REG_BINARY value set to 01:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\UsbFlags\IgnoreHWSerNum04036001


For port A of an FT2232 device with default VID and PID, the IgnoreHWSerNum string would be:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\UsbFlags\IgnoreHWSerNum0403601000


and for port B of an FT2232 device the IgnoreHWSerNum string would be:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\UsbFlags\IgnoreHWSerNum0403601001


As the FT2232 device also uses the Windows composite device driver, an additional IgnoreHWSerNum entry is required to prevent Windows from creating additional composite driver registry entries:

   HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\UsbFlags\IgnoreHWSerNum04036010


Now the system can treat devices with the same vendor ID and product ID but different serial numbers as the same device and drivers are installed for the first device only. As such, only one entry is created in the registry. If the device is connected to another USB port, the driver will have to be reinstalled for that port.

Note that IgnoreHWSerNum cannot be setup in FTDIBUS.INF or FTDIPORT.INF, it must be setup by editing the registry manually or by an installation utility BEFORE installing the driver.