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Trying to drive Ray Marine EV100 AP with a Garmin EchoMap SV plotter
I installed a Ray Marine AP into my friend's Hunter 340 last month, and as an independent unit following a heading, it works fine.
Now he has connected the subject Garmin plotter to the Ray Marine (RM) SeaTalkng (ST) network via a NEMA 2000-to-ST cable using a short blue/black ST cable from the tee to the end of original ST backbone. The tee was needed because the backbone was already full with the EV100 autopilot connections.
So the connections to the tee are Garmin, terminator, and short blue/black cable to the EV100's backbone.
The connections to the backbone are the aforementioned connection to the "Garmin" ST tee on one end and another ST blue/black cable from the other end of the backbone to the EV-100 compass unit where it connects to an ST tee with a terminator and a black/white connector to the compass (making two terminators total for the network) plus the network power, control head and "brain" cable connectors.
On the Garmin's communications page, the Raymarine components are seen; so we know their is at least one-way communication. However when a point is entered into the plotter and the go-to function initiated, the AP control head displays a "No Nav Data" error when it is commanded to follow the plotter.
We have tried all of the communication options from the plotter with the same end. Any suggestions?
Nav data such as XTE and Wpt Rng/Brng has defined PGN's that will transmit across N2 between brands, but there are no such standardized PGN's for pilot commands to engage, turn this way or that, or change mode from say steer to HDG or NoDrift or Wind Mode. Those commands are proprietary back channel comms that just happen to take place over the N2 network. So your Garmin plotter can certainly send nav data to a Ray AP, but it cannot tell it to engage. AP commands, like Radar commands, are proprietary to brand and won't migrate between different manuf.
Perhaps this http://forum.raymarine.com/showthread.php?tid=3007 would be helpful.