administrationservicestroubleshootingwindows
I am trying to figure out who's locking my COM port. Tried to search but could not find a way to figure that out. I am using XP.
Was wondering if 'Process Explorer' utility provides something for the same but could not find something helping.
Is there a command that shows up all the applications tied up to specific COM ports on the system?
Thanks
"Method Using Elevated Command Prompt"
From Start Menu type cmd into search bar right click on cmd.exe and select run as administrator
at UAC select yes to allow Windows Command Processor Program to make changes.
At the Command prompt type
SET DEVMGR_SHOW_NONPRESENT_DEVICES=1 (Followed by enter)
Then to open device manager type
DEVMGMT.MSC (Followed by enter)
In device Manager select View / Show hidden devices
Expand Ports (COM & LPT)
Hidden ports reserved will be shown with greyed out symbol & associated manufacturer / device type
To re-hide non present devices in future - from an elevated Command prompt type
SET DEVMGR_SHOW_NONPRESENT_DEVICES=0 (Followed by enter)
Try netstat -anb
C:\> netstat -anb
Active Connections
Proto Local Address Foreign Address State PID
TCP 0.0.0.0:80 0.0.0.0:0 LISTENING 1724
[Apache.exe]
Update: That a in -anb is there for a reason!
C:\> netstat /?
Displays protocol statistics and current TCP/IP network connections.
NETSTAT [-a] [-b] [-e] [-n] [-o] [-p proto] [-r] [-s] [-v] [interval]
-a Displays all connections and listening ports.
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Best Answer
Yes, in Process Explorer, the application using the port will have a "File" handle called
\Device\SerialNwhere N is a zero-based index.Update:
The "N" in "serialN" is not the COM port number, it's the index into the list of active ports. If you only have one port in use, it will always (?) be "serial0", and the second one you open will be "serial1". If you open them in the opposite order, the numbers will be reversed.
Check out the QueryDosDevice API. You should be able to iterate through COM1...COM? and get the "\device\serialN" entry for each open port. I'm not aware of a utility that will do this, you may need to roll your own.
There's a more COM-port-specific example here.