Device misdetected as serial mouse

Question

I\'m working on a device which communicates with a PC through a (virtual) serial port. The problem is that the data we are sending occasionally gets incorrectly identified b

Answer 1

I have encountered this Windows bug myself. Here is my own research on the topic:

Microsoft acknowledges this bug: http://support.microsoft.com/kb/819036 Start with downloading their tool and see if it solves the issue.

• Download & install their program.
• Run it from the command prompt from C:\program\Microsoft comdisable\
• Write comdisable /list when executing the program.
• All ports on the computer will be shown.
• Write comdisable /disable COMx where x is the port number.
• Do this for all ports on the computer.
• Reboot.

This should hopefully work as an universal solution.

Alternatively, you can hack in boot.ini but I don't believe this works in Vista/Win 7. I have some app note from Cisco systems describing how to do this. If the above doesn't solve your problem, please let me know.

Answer 2

I just encountered this problem myself on Windows 7 Professional x64, and a solution that worked for me was to go into the registry and edit the following value:

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

Change Value to 4 and it will stop this problem occurring.

Here is a list of all valid Start values:

0 Boot (loaded by kernel loader). Components of the driver stack for the boot (startup) volume must be loaded by the kernel loader.

1 System (loaded by I/O subsystem). Specifies that the driver is loaded at kernel initialization.

2 Automatic (loaded by Service Control Manager). Specifies that the service is loaded or started automatically.

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.

---

A reg edit command would be as follows:

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

You then need to restart the computer, which should now start correctly and not attempt to discover a serial mouse.

good luck.

Answer 3

If you have a "true" serial port, or an USB dongle (RS-232, RS-485, it does not matter) this problem can be worked around by first opening the serial port in question with a terminal, or whatever application you want to monitor it with, and only then plugging the device in. For your own sake, you should also pay attention to remove the device before terminating the connection.

With FTDI chips soldered on the device itself, you are busted. It took a few rounds for me to explain the management that a device communicating on it's own paired with an FTDI chip soldered on the PCB meeting Windows computers won't likely pass for user-friendliness, no matter how slick an USB socket may look like on the cabinet... (Thankfully, all these conditions coming together are quite rare and unusual)