You have to make sure you have your COM ports setup the same in both the Plugin and in Windows. To make life easier I've put a button called "Configure Port..." for configuring the port in Windows. You have to make sure that the Port Num, Baud Rate, Data Bits, Parity and Stop Bits match your ProLite, as well as the Windows port configured in "Configure Port..." and the settings in the plugin. I have tested the plugin with a Port Monitor and it works. You must get those settings right, and the "Test LCD" button should then output something.