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COM Ports Are Not Released When You Remove a Multi-Port Serial Controller
Article ID: 271523 - View products that this article applies to.
This article was previously published under Q271523
When you install a multi-port serial adapter on Windows 2000-based computer, the COM port numbers (COM3, COM4, COMx, and so on) that are assigned to the serial devices are registered in a COM port database. If the multi-port serial controller does not work, or if you remove it from the computer and then install a new multi-port serial adapter, the multi-port serial controller may use COM port numbers that start with the next available COM port number instead of re-using the missing or removed COM ports.
Missing COM ports are maintained to accommodate certain functions that are tied to specific ports. Microsoft recommends that you do not allow those ports to be claimed by another serial adapter, either temporarily or permanently. Before you install another multi-port serial adapter, use Device Manager or the Add/Remove Hardware tool to uninstall the previous adapter when it is still in the computer. When you do this, the assigned COM ports are unregistered and the new adapter can re-use the COM ports. To do this: