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Autopilot XTE data
#1
I have a simple setup with ocpn on pc with rpi running OP V2. OP signalk only receives opencpndata via UDP and forwards it to the AP via a 0183 serial usb.
After a slightly troublesome connection problem, it now works. However, if I set the AP to track mode, using an Opencpn route that I want to follow. It accepts the command but very quite triggers a large XTE alarm. If I zero it on opcpn, it's ok for a bit but soon returns. Looking at the data, I am curious, as the signalk data checker shows the XTE in meters, but the Raymarine display shows the same numbers, but as NM hence the error. So if the XTE is 0.01Nm, the same data is 185m on signalk but 1.85nm on the Raymarine display. The next number is 370m for 0.02. etc
If I connect the usb output directly to the pc and Opencpn, it's fine so OP is doing something strange.
Any help?
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#2
So to clarify, somehow openplotter corrupts the XTE data as it passed though the multiplier. It seems to multiply the input by 10. If I simply connect the usb rs422 to the pc with opcpn, there is no problem. This would appear to be a bug. The track function isn't useable.
Should I report somewhere?
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#3
If I am not wrong the signal k key for XTE is:
/vessels/<RegExp>/navigation/courseRhumbline/crossTrackError
and this key uses meters as unit and your Raymarine is expecting nm. OpenCPN uses nm too and this is why it works directly. If opencpn is sending NMEA 0183 to signal k using nm why signal k is fowarding NMEA data in meters?
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Edit: is that UDP connection opencpn -> signal k a NMEA 0183 connection?
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#4
[quote='Sailoog' pid='16198' dateline='1601387351']
If I am not wrong the signal k key for XTE is:
/vessels/<RegExp>/navigation/courseRhumbline/crossTrackError
and this key uses meters as unit and your Raymarine is expecting nm. OpenCPN uses nm too and this is why it works directly. If opencpn is sending NMEA 0183 to signal k using nm why signal k is fowarding NMEA data in meters?
---------------------------------------------
Edit: is that UDP connection opencpn -> signal k a NMEA 0183 connection?

Yes, it's UDP to signal k as a nmea0183 connection. Can I generate a time series of the XTE to see how it changes. It's in meters in the data viewer. I do have signal k to nmea0183 plugin enabled. Is that necessary?
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#5
I have disabled the signal k to nmea0183 plug in, and that has solved the problem.
Curious!
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#6
There is a change in the latest (1.7.1) version of the signalk-to-nmea0183 plugin, which should fix this issue.
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