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 Logger cannot open a COM port


A device communicates with a computer through a (virtual, USB) serial port. The device frequently sends data to a computer. It occasionally gets incorrectly identified by Windows as a bus mouse, after which the "Microsoft Serial Ballpoint" driver is loaded. Windows blocks the corresponding COM port, and the logger cannot use it. The logger shows the "Device already open" error.


You need to disable a driver for a serial mouse in the Windows registry.

1. Start regedit.exe

2. Go into the registry and edit the following value:

Location: HKEY_LOCAL_MACHINE\System\CurrentControlSet\Services\sermouse  
Key: Start  
Value: 3

Alternatively, you may use the following command:

REG ADD "HKLM\SYSTEM\CurrentControlSet\Services\sermouse" /V Start /T REG_DWORD /F /D 4

3. Change "Value" to "4".

4. Reboot the computer.



3 - Manual. Specifies that the service does not start until the user starts it manually, such as by using Device Manager.

4 - Disabled. Specifies that the service should not be started.


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