Applications often only connect to ports shown in the Device Manager.
In case NavMonPC (or e.g. GpsGate) ports are not shown there you could try the following (in Win7)
Go to Control Panel>Device Manager
Select (highlight) "Ports (COM & LPT)"
On Menu at top of window select Action>Add legacy hardware
Click Next select "Add the hardware
that I manually select from a list" then Next
Scroll down list to Ports (COM & LPT) & highlight then Next
A window will appear with Manufacturer & Make columns, these should be already set to (Standard Port Types) & Communication Port respectively - ensure they are & press Next & Next again to confirm
This will add device with next available COM number. Change this to match the NavMonPC COM port number that you also wish to use with your software
• Right click on the COM port with yellow exclamation mark in Device Manager. Select "Properties".
• Click on "Port Settings" tab
• Click on "Advanced..." button
Select the matching "COM Port Number" in the drop down with the same name.
• For some applications it is necessary to set the speed of both receive and transmit buffer at a low value, e.g. 33%, otherwise these applications will not "see" the port
• Click OK on all dialogs.
Repeat all of above for any additional COM ports that need to be listed under Device Manager.