I have installed an Actisense NMEA converter to transmit Sat compass SCX-20 heading data to a Navpilot 500 autopilot. I am troubleshooting an issue with the heading updating only when I turn on the AP, then the heading data does not refresh. What baud rate should I be using in the Actisense config? Second question. Is it possible to use the NMEA0183 output from the TZT2BB to provide heading data to the AP, assuming the heading data in that case would come from the SCX-20 sat compass on the network. This would eliminate the need for the Actisense converter wouldn't it? Thanks for your input.
TZT2 heading output to Navpilot
- Thread starter donpjr
- Start date
Good questions. First off, you can't use the 0183 output of the TZT2 to drive heading to the pilot. While it will pass the SC20 data, it will not be updated/sent fast enough to make the pilot happy. The heart of an autopilot is the heading and hydraulics. The Actisense should work fine once all configured. You want to custom config the output sentences so it only provides heading data like $HDG and turn everything else off. The pilot heading port (TB8 on NP500 series) won't like it if you shove other sentences there. The baud rate isn't as important but it needs to match what you setup in the Sea Trial menu for the compass setup. It would be good if you used 38,800 and ensure that the compass setup is set to "OTHER". You got this. You can still use the TZT2 0183 to drive GPS and steering data to the pilot on TB7 to drive the boat.
I downloaded the Actisense configuration and updated it to the following:
NMEA0183 - checked the HDT (heading true) transmit box.
NMEA2000 - checked the HDT receive box and set update rate to 200ms. This is the only place where update rate can be set so I set it to 200 based on AP500 install manual.
I set the AP dockside setup compass to "other" and baud rate 4800
I changed the Actisense baud rate to "fast heading 4800". It was on 38400 before.
No other parameters in the actisense are checked except the above.
When I turn on the AP it provides a heading that matches the boat compass, but it only provides the current heading and it does not change as the boat heading changes. So I am still not getting a refresh of the heading from the Actisense unit. Any ideas on issues with my setup? I tried the 38400 baud rate and got the same result. I have confirmed that the heading to the AP is coming from the Actisense unit as if I unplug the Actisense I don't get any heading to the AP, and get a missing heading alarm. Something in my Actisense setup seems to be wrong. Looking for ideas.
NMEA0183 - checked the HDT (heading true) transmit box.
NMEA2000 - checked the HDT receive box and set update rate to 200ms. This is the only place where update rate can be set so I set it to 200 based on AP500 install manual.
I set the AP dockside setup compass to "other" and baud rate 4800
I changed the Actisense baud rate to "fast heading 4800". It was on 38400 before.
No other parameters in the actisense are checked except the above.
When I turn on the AP it provides a heading that matches the boat compass, but it only provides the current heading and it does not change as the boat heading changes. So I am still not getting a refresh of the heading from the Actisense unit. Any ideas on issues with my setup? I tried the 38400 baud rate and got the same result. I have confirmed that the heading to the AP is coming from the Actisense unit as if I unplug the Actisense I don't get any heading to the AP, and get a missing heading alarm. Something in my Actisense setup seems to be wrong. Looking for ideas.
You might call Actisense and see if maybe they had a known issue and they have some newer firmware than your unit has. If that doesn't offer any help; I would recommend putting the 0183 into some sort of NMEA monitor and look at the data to see if it is changing correctly or putting out what appears to be the same heading number. I have never saw a pilot input have an issue like you describe so the odds are it has to do with the converter. Sounds like it is converting and then locking up on one heading.
View attachment NMEA reader output.pdfHello Johnny, I have communicated with Actisense and connected their NEMA Reader software to the Actisense NGW-1. I attached the file showing the output. I can see the unit is transmitting the following O183 data. HDG and HDT every .2 seconds. And THS every 1 second. The heading data is updating at every transmission so it appears the Actisense unit is transmitting and updating heading data. The AP is only capturing the initial heading number when I turn it on and does not refresh. In the testing I also noted that if I don't send HDT to the AP I get a "missing heading" error and an alarm. I'm not sure where to go from here. In the configuration of the Actisense I only turned on Receive 127250 @ 100ms rate. And for the 0183 side I checked HDG and HDT, each at 200ms refresh rate. I do note that in the N2000 side there is a sentence called PGN 126208 – NMEA Command Group Function. I'm not sure what this is or what it does, I didn't notice it until after I tested. Any ideas for next steps?
The Navpilot is an older pilot and it might not like NMEA v3 (or v4) that the converter might be providing. Have you tried setting the converter to use v1.5 or v2 NMEA to see if that makes a difference?
Thanks Johnny. I will ask Actisense if it's possible to configure the unit to send the older NMEA format. I don't see that referenced anywhere in their manuals. It looks like I might be nearing the end of the experiment to send my sat compass heading data to the autopilot and I will continue to use the PG500 unit. I don't really know what else to try to make the heading data valid for the AP to use.
donpjr":rphvvw38 said:
I had a chance to look at the data sentences captured. I noticed that the HDG sentence has a null field that is not actually outputting a heading value. It looks like only HDT and THS has a heading value. Can you turn off HDG from being output with the actisense software. You might also try to turn off THS as well.
C-Bass
Hello C-Bass. I can turn off the HDG, not sure about the THS but I will check that as soon as I can connect again. Do you think it matters what the refresh rate is for N2k incoming heading? I set it to 100ms as the sat compass says that is the default compass output rate and it is what I have it set at in the MFD.
I will test your suggestions tomorrow and advise. Thanks,
I will test your suggestions tomorrow and advise. Thanks,
C-Bass. I have configured the Actisense as you suggested. Only heading is received from the sat compass and HDT is sent to the AP. The AP did the same as before, receiving only a single heading upon startup and it does not refresh. I have attached the NMEA reader output showing that only HDT is being transmitted and I could see it was updating. The only odd thing I notice is the interval is .16 and I expected it to be .20.
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