Client Server App (C/.Net)

We require a client server application that will send a serial string out a COM port. Basic design would include a [login to view URL] that can sit on our SQL server to be called from TSQL, variables need to be a deviceid and a code eg [login to view URL] -d5070 -cE1234 The client needs to then connect to the [login to view URL] across a VPN and format the variables into a template and send this out the COM port. The server side of the application needs to respond to a 'check' protocol from the device the com port is connected to and also be able to respond on a specific port to our monitoring software