So far, I have not been able to find a way to communicate routing information through signalk to pypilot. I cannot find any additional 'path' in signalk's data browser to reflect a bearing to waypoint when either the OpenCPN stock routing is active, or the autopilot route plugin is active. Neither could I find any code in either the autopilot route plugin or pypilot that would utilise such a path.
So the answer would be yes, you would have to send at least APB messages to the 20220 socket of pypilot to be able to follow a route. I'll give it a quick test here to see if the pypilot plugin Forward NMEA option would suffice. Stand by.
EDIT: First, you were right in that the native signalk to pypilot connection does not activate the GPS mode. I was wrong in that and I have updated my previous post.
Second, Forward NMEA does forward the APB and RMC messages, so it would suffice. However, it does also forward many superfluous messages to pypilot, which is a waste of cpu cycles on either side in my opinion. Therefore I would suggest a proper data connection, with an output filter allowing only RMC and APB messages. And WMV messages, if you want to explore the Wind options.
So the answer would be yes, you would have to send at least APB messages to the 20220 socket of pypilot to be able to follow a route. I'll give it a quick test here to see if the pypilot plugin Forward NMEA option would suffice. Stand by.
EDIT: First, you were right in that the native signalk to pypilot connection does not activate the GPS mode. I was wrong in that and I have updated my previous post.
Second, Forward NMEA does forward the APB and RMC messages, so it would suffice. However, it does also forward many superfluous messages to pypilot, which is a waste of cpu cycles on either side in my opinion. Therefore I would suggest a proper data connection, with an output filter allowing only RMC and APB messages. And WMV messages, if you want to explore the Wind options.