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Old 02-08-2015, 23:13   #16
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Re: OCPN to Autopilot problem

Originally Posted by jongough View Post
Looking through the manual for the 3100 there appear to be three modes, compass, GPS & wind. In GPS mode if you have WPT AKN set on, it will raise an alarm and wait for the user, you, to acknowledge the alarm before going onto the next waypoint. Is this possibly the problem? If you send only APB messages to the unit and turn off WPT AKN does it work better or just the same?

G'Day Jon,

I've tried it both ways: waypt ack off and on, and with APB, and with ECapb and ECrmb as suggested. They all seem to behave the same way. It does not follow the protocol shown in the user guide... says route ends instead of next waypt?


I can of course reset GPS auto mode and it will then steer to the next waypoint and alarm when it gets there. For routes where the wp are far apart, this isn't a problem, but one of the few times I have used this feature (with my old Northstar GPS) was running a tricky entrance with several quick turns, in the pitch black and with a cyclone approaching (Vanuatu). Worked well then, allowing both Ann and I to concentrate on peering into the black and hoping to see the reef before we hit it... if the A/P failed! A scary night... and having to go through the reset at each wp wouln't play well, I fear.

Thanks for your thoughts on this, Jon.


Jim and Ann
s/v Insatiable back in MBTBC marina, waiting for next eye jobs to be done
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Old 03-08-2015, 16:50   #17
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Re: OCPN to Autopilot problem

It appears that the autopilot thinks you are sending a 'goto here' or a single segment route, so once it arrives it does not know what to do. I think you need to try and see what happens using APA & XTE only, APB only, RMB only. You will need to also have the trace window open for the port that you are sending these to the autopilot. This will show you what sentences are actually going to the autopilot and their contents.

When I was testing I got out in the middle of Morton bay and setup tests with routes/segments about 0.5nm or less to see what would happen. Can you do this?

One other thought, how does your autopilot know it has reached a waypoint? In OCPN you set the distance from the waypoint which you think is acceptable for arrival. In some cases 1nm may well be OK, in others you may want 10m (tight channels etc.). Is your autopilot saying you have arrived and OCPN still thinks you have a distance to go? You could test this by setting a large arrival radius on OCPN (100+m) and see what happens when following a route.


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