What Garmin protocol GPS library for .NET exists

I'm developing a GIS application and I had been using devices that output NMEA protocol. There are lots of libraries for NMEA devices, but for Garmin there is only one that I have found, and it isn`t very complete: OpenGPS.NET

I have two questions:

1. How do I use the library with a USB device that does not create a virtual com?
2. Are there other, preferably free, Garmin libraries?

I have also used Franson GPSgate to convert Garmin to NMEA, but there is a problem when the computer goes into sleep mode. When it returns I have to reset the GPS device.