serial port communication from two Application

I am facing one problem in my office. We are having one pc connection with a serial port device ( HSM ) which is used by one applicaton. It is working fine. Now we are using one more application to connect with that serial device. But, occationaly the device is give "Device is not functioning error". My doubt is whether two application can use single serial port device simultaneously ?. If so, any configuration required ?. If not, Is there any other way to do this ?.
Pl. can help to solve this issue.

so far as i know, you can't open the serial port which is already in use.

-thankyou

Maybe you could create an application that communicates over the serial port and have your other 2 aplications communicate with this application.

It's just an idea I don't know how succesfull it would be, you would need the application that uses the serial port to manage the other 2 by queueing requests so they don't interfear with each other or receive each others responses.

I have a custom application that shares a common serial port with two or more remote computers. A server app is installed as an NT service on the computer with the serial connection. The remote clients connect to the server via an ethernet connection and the server "shares" the serial port with the remote connections. Thus, you may want to try something similiar to this.

Thanks. Quantum, bob. This idea will work i think. let me try this. once again thanks.