I need to develop a Windows Form application that communicates with a device that is connected via Com1.  This will allow the application to report current parameters on the device as well as change parameters. 

First trick is the communication link with the device needs to be kept active so the device won't drop the link.  I'm thinking some kind of timer to trigger the sending of a standard command to the device.

  Second trick is I need to have access to the device from third-party program through a DLL. I'm thinking of using WCF service for a link to my custom program or should I just write all the device communication into the WCF service and have both the DLL and my Windows Form applicaiton pull information from the WCF service?

Any guidance or help would be appreciated.  I have no problem writing stand-alone programs it is just the communication between applications I have confusion about.

Thank you,

BubbaGee