I think I have been able to reproduce your issue:
Raymarine E80 connected to a GPS by NMEA 0183.
Raymarine E80 connected to MacArthur HAT by alternative Seatalk wiring (red wire to DATA, yellow wire to GND, black wire unconnected, ST GND jumper open, Invert signal: yes).
Since I am indoor at the lab, I have not GPS fix, so the E80 is sending only its own data, navigation.magneticVariation.
The Signal K Dashboard shows 0.4(100%) for the seatalk connection.
The signal K Data Browser shows just navigation.magneticVariation key updated every 10 seconds.
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I think something is muting your devices as soon as you use the alternative connection and only data from the C80 is received. Could you check if that 0.4 belongs to navigation.magneticVariation or anything else from the C80?
These Raymarine displays have a useful tool to check the traffic in your bus. Go to Menu - System Diagnostic - External interfaces - Seatalk - Buffer. There you can filter by TX, RX or both. Please check this traffic when connecting/disconnecting the MacArthur and we will see if the devices mute or they keep talking but the MacArthur stop listening or whatever...
Question: where exactly do you make the connection?
Another theory could be that this alternative wiring only works for self-powered devices (C80) and devices powered from the bus (ST60 Depth, ST60 Wind) can not be read but I have not any electrical explanation for that.
Raymarine E80 connected to a GPS by NMEA 0183.
Raymarine E80 connected to MacArthur HAT by alternative Seatalk wiring (red wire to DATA, yellow wire to GND, black wire unconnected, ST GND jumper open, Invert signal: yes).
Since I am indoor at the lab, I have not GPS fix, so the E80 is sending only its own data, navigation.magneticVariation.
The Signal K Dashboard shows 0.4(100%) for the seatalk connection.
The signal K Data Browser shows just navigation.magneticVariation key updated every 10 seconds.
----------------------------
I think something is muting your devices as soon as you use the alternative connection and only data from the C80 is received. Could you check if that 0.4 belongs to navigation.magneticVariation or anything else from the C80?
These Raymarine displays have a useful tool to check the traffic in your bus. Go to Menu - System Diagnostic - External interfaces - Seatalk - Buffer. There you can filter by TX, RX or both. Please check this traffic when connecting/disconnecting the MacArthur and we will see if the devices mute or they keep talking but the MacArthur stop listening or whatever...
Question: where exactly do you make the connection?
Another theory could be that this alternative wiring only works for self-powered devices (C80) and devices powered from the bus (ST60 Depth, ST60 Wind) can not be read but I have not any electrical explanation for that.