To run comdump for COM port 3 or 4, you must know the interrupt request for the COM port. You can find this in the Device Manager:

• Start, Control Panel, System, Device Manager (for Windows 2000 and XP, click the Hardware tab after opening System, then click the Device Manager button).
• Open the Ports item, then open the COM port for the touchscreen. Click the Resources tab, then record the setting for the IRQ resource.

The command line format for COM3 or 4 is:

• comdump # 9600 IRQ#
  • where # is either 3 or 4 and IRQ# is the IRQ number that you got from Device Manager.