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Frequently Asked Questions

Changing the COM port number for your Keyspan USB-Serial Adapter

If you purchased a Keyspan adapter from AVL or elsewhere, you may have trouble getting to the correct COM Port. The latest version of WeavePoint allows COM 1-7. WeaveMaker Mi and older versions of WeavePoint accommodate for COM 1-4 only. However, the Keyspan software will often assign the Keyspan adapter a COM Port number higher than is required by your loom control software. Here's how to make the change.

Step 1 - Ensure that you have installed the latest Keyspan driver software for your adapter

You can download the latest from:

Select Category: Drivers, then Subcategory: Keyspan Products.

Step 2 - Verify the Keyspan COM port in the Keyspan Serial Assistant

To do this, go to the 'Start' menu -> 'Programs' -> 'Keyspan ...' -> Keyspan Serial Assistant. This will open the Keyspan Serial Assistant.

In the Keyspan Serial Assistant, click on the 'Adapter Status' tab. This will show your Keyspan adapter and the current COM port number (i.e. COM4, COM 5, etc.).

Step 3 - Changing the COM port

Click 'Port Mapping' tab. Once you are in the 'Port Mapping' section select or highlight the Keyspan COM port that you wish to change. With your Keyspan COM port highlighted, select the COM port number that you wish to change to from 'COM Port mapping for the selected adapter port' pull down menu.

Important: Please note that you can select any COM port you wish however, you may notice that certain ports are 'in use'. This may mean that there is hardware connected to these COM ports or they have been reserved for the operating system or other software. Changing the COM port mapping to a COM port that is in use may render any hardware and/or software using that port inoperable.

Once you have finished setting up the new COM port number, click on the 'Adapter Status' tab in the Keyspan Serial Assistant to verify your new COM port number.


Changing a COM port is not recommended and can cause serious problems with your computer. The Keyspan software automatically selects the COM port avoiding all those that are 'reserved' by other software/hardware components. For example, if your Keyspan adapter creates COM9, which means that COM1 through COM8 have all been 'reserved'. Reserved COM ports will not show up in the Windows Device Manager and are often tied to software devices (and not physical serial ports). According to the rules of COM port creation, set by Microsoft, any device that creates a COM port must respect 'reserved' COM ports (i.e. if COM8 is 'reserved', a device can't become COM8, that device needs to keep trying COM ports until it finds a 'non-reserved' COM port in the Windows registry).

That being said, the Keyspan software allows you to overwrite 'reserved' COM ports. This is done via the PORT MAPPING tab in the Keyspan Serial Assistant (see above for instructions).

IMPORTANT!!! The Keyspan software will allow you to overwrite 'reserved' COM ports but this can cause serious problems to your computer. This feature is not supported by Keyspan and may not work in all cases depending on the state of your Windows registry. We can provide you information on how to override a COM port but if you have any problems (i.e. like your hard drive being erased or worse), you will have to solve these issues on your own.

Troubleshooting Keyspan Software Info:

This FAQ ASSUMES that: a) your COM port is list in the 'Adapter Status' tab AND b) the same COM port is listed in the 'Port Mapping' tab.

If your Keyspan adapter is NOT listed in the ADAPTER STATUS tab, contact Keyspan and let them know this information. They can troubleshoot the problem from there.

If your Keyspan adapter's COM port is listed in the ADAPTER STATUS tab BUT that COM port is NOT listed in the PORT MAPPING tab, this means that the Keyspan software can't get access to your Windows registry. This can be because a) you don't have Administrator privileges on your Windows 2000/XP computer, b) you have some software preventing the Keyspan software from accessing the Windows registry like a virus/virus protection software/spyware app that aggressively protects the registry/or something similar, OR c) your Windows registry is damaged. If you have this issue, please let Keyspan know if any of these 3 cases apply to you and they will provide further instructions.