Windows 2003 keeps serial port locked


I have a Portserver TS and i installed it on a windows 2003 server.
I got a serial port nr 3. Thia one i used for a modem connection. This worked ok for 3 days. Now i get the error “serial port is in use” i have rebooted windows, the portserver and the modem. I have disabled the device in the windows device manager, rebooted the server and then connected it again. Directly the serial port was in use again. This error i get when i do a quiry on the modem.

I hope you can help me get the modem working again.


You should open the device manager->muliport serial adapter and look at the advanced properties of the realport driver. If you highlight the comport you will see port status this will tell what has the port open. You should also click on the advanced tab and enable do not scan modems on boot. This will prevent windows from scanning the serial ports for serial devices which maybe causing you issue.

Also, make certain the Portserver port is configured to use the RealPort profile, as it is not the default.

This can be checked from the root prompt of the PortServer:

#> set port

The dev setting should show “rp”. If not:

#> set port dev=rp ra=1
#> kill tty=1

In addition to Wingmaster’s suggestions, you can also log into the PortServer TS (PSTS) with your browser. If you have new enough PSTS, under Management, Connections, you should be able to see if a connection is open and source of that connection. You could have RealPort installed on another PC and an application from that PC could be opening the port. Or without RealPort being installed, an application which opens a socket connection may be the problem. A Wireshark capture may also help you determine the source of the problem. If the port is configured for UDP, the attached device may be opening the port.

Thanks for your help.
I got the port free again.
After 1 day the port is locked again.
I need to put the device in a production envirement.
I cannot make modications to the system every day.

What do you think i should do?



Lastly, check under Administration > Device Information > then click on the port which is “stuck”. Check to see if the OFC or IFC signal shows green, which would indicate the port is stuck in a flow control state, indicator of a flow control mismatch between the physical serial device you have plugged into your Portserver and the way its being setup by the application using your Realport comm port.