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usb2comport

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USB to COM Port Mapping

The Problem

When connecting our ECMLink cable to the laptop, the FTDI driver used by our cable wants to assign different COM ports to each cable. This is not practical for a laptop used by a shop or general tuner when connecting cables from multiple customer cars.

To correct this, you can tell the FTDI driver to use a fixed COM port for each physical USB port on your laptop.

The Solution

To tell the FTDI driver to always assign the same COM port to a physical USB port, you have to edit the following registry key:

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Services\FTDIBUS\Parameters\LocIds

In this key, you will specify the location IDs of each USB port you plan to use.

To obtain the location IDs of your physical USB ports, use the USBView application. When you run this application, you will be presented with a screen as shown below. Of course, the laptop on which you are running this application will have a different configuration.

First, select the Options→Location IDs menu item and then hit F5 to refresh the screen. The above screen will now look like the one shown below. Notice that the Port numbers from the first screen are now shown as Loc numbers. Those are the physical location IDs of the USB ports on your PC.

To determine which two location IDs correspond to a physical USB port on your laptop, simply insert one of our ECMLink cables into the port in question. Once you have inserted this cable, hit F5 again to refresh USBView. Now you will see something like the following (notice the new USB Serial Converter at Loc41).

usb2comport.1251888568.txt.gz · Last modified: 2009/09/02 06:49 by twdorris