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Old 09-06-2023, 05:22   #1
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Mag HDG Issue

My wind, depth and speed instruments are Raymarine Mn 100-2 wireless with a hull receiver and transmitter. As they are NMEA 0183 I use an Actisense NGW1 to pass the data into my NMEA 2000 network where the data is successfully read by the plotter. The magnetic heading is supplied from a sensor directly connected to the nmea 2000 backbone. This is primarily for the radar but the value is seen and correctly displayed on the chart plotter and by the wind instruments via the NGW1. I use a DigitalYacht Navlink 2 to supply the nmea 2000 data as 0183 to tablets and signal k/opencpn on the Raspberry Pi.
Now for the strange part. With the wind etc instruments turned off, the magnetic heading is seen by the Navlink 2 as $IIHDG,47.8,0.0,E,1.4,E*77 and is transmitted correctly to everything relying on the Navlink via the Wi-Fi router. As soon as the wind instruments are turned on this data is no longer transmitted and everything depending on the Navlink 2 displays only the last data, frozen. All equipment on the NMEA 2000 backbone sees the data correctly. There are no filters switched on the Navlink 2. One downside of this is that my own boat displays on opencpn as heading in a different direction to the COG. Iíve asked DigitalYacht if they can help given that the problem is downstream of their device but they havenít replied.
Can anyone throw any light on why this is happening and how it may be remedied please.
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Old 09-06-2023, 12:46   #2
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Location: Orust Sweden
Boat: Najad 34
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Re: Mag HDG Issue

First Q and test for you:
Your HDG is reporting a magnetic heading and variation is 0.0 (good!):

Do you have the plugin WMM enabled? With you data WMM should create a true heading.
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Old 09-06-2023, 23:31   #3
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Re: Mag HDG Issue

Hi, thank you for your help. I do have that plug in enabled. With the Raymarine instruments mentioned above switched off the magnetic heading reads correctly in Signalk and Opencpn. From that I assume everything at that end is ok. When the Raymarine instruments are turned on the data disappears after the DigitalYacht converter.
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Old 11-06-2023, 10:39   #4
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Re: Mag HDG Issue

I am using Openplotter HDM data from Pypilot for my navigation and would like Signal K to transmit the data HDM to my Simrad NMEA 0183 instruments. What Signal K commands do I need to do this?

Openplotter readily accepts all of the Simrad data (wind, speed, depth, etc) but I have been unsucessful in sending data back to the instruments.
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