Hi Ian, after going through the process of finding a copy of Hyperterminal, Windows 7 - 8 don't have it, doing a loop back then figuring out how to get Realterm to work
I finally managed to get the GPS puck's output to display on the second computer so I knew that OpenCPN
was passing through the GPS sentences and also three others it was generating itself. However when I reconnected it with the autopilot it would not work. Finally, in desperation, I reversed the two output conductors on the converter and it all sprung to life. Perhaps the 0183 inputs labeling on the autopilot has the polarities reversed. So the solution you suggested is the correct one.
Whilst I was wandering around in one of the other OpenCPN threads I noticed a post which stated that the BU-353 does not support Variation so I checked the other puck
which is a Holux GR-213 and it does not support it either, the sentence is included but there is nothing in the field. Consequently I located and downloaded the WMM software
but have not figured out which version will work with Win 8 so have not installed it yet.
I am now fully retired and a permanent live aboard because I cannot stand the weather
for about eight months of the year where my home is situated. Consequently mucking about in boats is pretty well my main recreational activity. My first computer was an 8bit Z80 kit on which I learned to program in basic. Optimum software
capabilities are somewhere between the Z80's Basic and Win 8 I am battling with at the moment. I am tending to the opinion that they should have stopped at XP. I have used four nav programs and OpenCPN is the best of them so I have decided to learn as much as I can about it and use it's capabilities as much as I can however I am finding it a bit of a struggle.
Your advice has proven to be correct on both counts, thank you and sincere regards, Raymond.