Ports Won't Install At COM3 in Windows 2000/XP

When the XR17C15x based cards are installed in Windows 2000 or XP, the new COM ports should start at 3 (or 5 if there are 4 built in serial ports). But sometimes you may see them start at a much higher number. This may be due to:

·  There was a card previously installed in the system, and although the physical board was removed the adapter was not removed from Device Manager.

·  A previously installed card was not completely removed from the registry when the adapter was uninstalled.

 

This can be fixed by doing:

·  The XR17C15x based adapter must be removed from Device Manager even though it no longer appears. Follow the instructions given in Appendix A.

·  To remove extraneous COM ports from the registry, follow the instructions given for removing phantom ports in Appendix B.

 

 

Appendix A:

How to Clean uninstall the PCI card on my windows 20000/XP system

This will involve 2 steps:

1.      Uninstall the old driver from Device Manager

·        In the device Manager find the PCI card under ''Multi-port serial adapters''. Right click on the adapter and choose the uninstall option.

2.      Delete the “OEM” related old oem*.inf and oem*.pnf files

·        Go to \winnt\inf (Windows 2000) or \windows\inf (Windows XP) directory. Look for oem*.inf files. Open these inf files and mark the files which contain either “; ser15x.inf “ or “; oemport.inf” in the first line. Delete both the corresponding oem*.inf amd oem*.pnf files.

 

 

 

 

 

 

 

 

 

 

 

 

 

 


 

Appendix B:

I have phantom serial ports in Windows 2000/XP. How can I remove them?

First, remove all non-standard COM ports (remove any Multi-port serial adapters from the device manager, as described in Appendix A).

Most likely there are leftover entries in the registry. You can run regedit to remove the extra entries.

NOTE: Make a backup of the registry prior to taking any of the following steps. You edit the registry at your own risk.

·        Run regedit. Go to: HKEY_LOCAL_MACHINE/SYSTEM/CurrentControlSet/Control/COM Name Arbiter

The Data field of COMDB may show COMDB = FF FF FF 03 (or something similar).

It should have:

COMDB = 03 00 00 00, if you have 2 built-in serial ports (or 01 00 00 00 if you only have one built-in COM port).

NOTE: 03 in binary is 0000 0011 so the lowest bit set (the 1 on the right) means COM1 is in use, and the bit to its left, in the 2 position, means COM2 is set.

Also, clean the keys for any non-standard serial ports from these places:

  • HKEY_LOCAL_MACHINE/HARDWARE/DEVICEMAP/SERIALCOMM
  • HKEY_LOCAL_MACHINE/SOFTWARE/Microsoft/Windows NT/CurrentVersion/Ports

You should be able to power down and reinstall the XR17C15x based adapter if it had been removed from the system. If it is installed, reboot the system. The adapter should be redetected and the driver installed. The com ports should now default to start at COM3