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Old 23-10-2019, 22:24   #1
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Heading info not being accepted/used

I have a TMQ AP4 autopilot, which is working well. I want to use its magnetic heading info to assist in radar operations, plus other options within O5.

I have connected the nmea port and created a new connection. The nmea debug window shows that heading info is being received by O5, but it is not being utilised.

In comparison, a Bluetooth connection from my phone compass does get utilised and displays both magnetic and true heading.

So why is the AP heading being ignored?
The full sentence is
$APHDM, 133,M*08<0x0D><0x0A>

The 133 changes as the heading display on the AP changes

There is no HDG or HDG message received from the autopilot.

Any suggestions will be gratefully received.

Tim
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Old 24-10-2019, 02:51   #2
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Re: Heading info not being accepted/used

Tim,

The checksum may be incorrect. One calculator I used shows that it should be '0C' not '08'. Could you try telling OpenCPN to ignore the checksum? I fed the amended sentence into OpenCPN and the ship's heading showed correctly, and rotated the icon.

Mike
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Old 24-10-2019, 04:36   #3
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Re: Heading info not being accepted/used

Hi Mike
Thanx so much for your thoughts.
I have unchecked the Control Checksum button.
I click Apply
I click OK (which exits the connections and options window)
The heading data, shown as being received in the nmea debug screen, still does not appear in dashboard etc.
I go back to Options>Connections, and find that Control Checksum is ticked (checked) again.
Tim
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Old 24-10-2019, 05:02   #4
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Re: Heading info not being accepted/used

Tim,

With settings disable the checksum. In "Input Filtering", "Accept only sentences" make sure that the line includes "HDM".

By itself 'Checksum' setting does not get retained on my PC, but if you change the sentences you want to receive it is retained. You may have to play with adding another sentence to get this working.

Mike
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Old 24-10-2019, 05:11   #5
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Re: Heading info not being accepted/used

I thought I had disabled checksum. But it comes back. Is there another place to disable it?

I have set the input to receive only the HDM message. In the nmea debug window, I can see HDM come in and it stays in black text which I understand means it is accepted.
It just doesn't appear to get "used". The magnetic heading field of Dashboard stays as blank (---).
I wonder if OpenCPN version 5 dropped the recognition of HDM as a valid sentence.
Are you running O5 or O4.8?

Tim
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Old 24-10-2019, 06:44   #6
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Re: Heading info not being accepted/used

I am running OpenCPN 5.0. After adding "HDM", then 'Apply', 'Ok' the checksum stays unchecked. What about clearing all the messages that are filtered using the ... button on the right of the line? This still allowed me to retain the checksum unchecked.

Mike
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Old 24-10-2019, 07:08   #7
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Re: Heading info not being accepted/used

Now I am having the same problem as you! Attached is 'testnmea.txt' which is your sentence with the checksum corrected. 'testnmea8.txt' is your original sentence. Using the VDR plugin 'testnmea' works correctly, 'testnmea8' does not, with checksum disabled. I think we have a bug in the main program.

Mike
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File Type: txt testnmea8.txt (576 Bytes, 8 views)
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Old 24-10-2019, 11:02   #8
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Re: Heading info not being accepted/used

Tim...


Check these settings if relevant for your AP. Page 36
https://www.tmq.com.au/downloads/TMQ/AP4.pdf
Try different settings in combination with OCPN with or without "Use Checksum"
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Old 24-10-2019, 11:41   #9
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Re: Heading info not being accepted/used

Hakan
Thank you for this manual.
It is a more recent version than the one I have. But it also relates to a firmware version more recent than I have. Unfortunately!
I tried the steps as outlined on page 36.
The programming code 900 appears. I can cycle through 900 to 910, but cannot reach 912.
Therefore I don't think I can select different heading outputs.
I will confirm this later today with the manufacturer during office hours. And find out if the firmware can be updated, which I think is doubtful.
But the $HDM *is* being sent. It *is* being received by O5. It just doesn't seem to be getting used.
I don't know what effect Checksum has on this.

Tim
Quote:
Originally Posted by Hakan View Post
Tim...


Check these settings if relevant for your AP. Page 36
https://www.tmq.com.au/downloads/TMQ/AP4.pdf
Try different settings in combination with OCPN with or without "Use Checksum"
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Old 24-10-2019, 12:04   #10
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Re: Heading info not being accepted/used

Quote:
Originally Posted by Rasbats View Post
Now I am having the same problem as you! Attached is 'testnmea.txt' which is your sentence with the checksum corrected. 'testnmea8.txt' is your original sentence. Using the VDR plugin 'testnmea' works correctly, 'testnmea8' does not, with checksum disabled. I think we have a bug in the main program.

Mike
There is a space in before the heading in both those files. That should not be there.

Chris
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Old 24-10-2019, 12:25   #11
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Re: Heading info not being accepted/used

Mike
Thank you so much for working on this.

I have managed to get the Control Checksum box to stay empty.
I did this by adding the HDM sentence to the Accept sentences list twice.
The nmea debug utility shows the heading info mostly coming in as *0 instead of *8.
But that heading figure is still not appearing in the magnetic heading field of Dashboard.
I have no idea what the effect of Checksum is, but it hasn't made any difference that I can see.
Quote:
Originally Posted by Rasbats View Post
Now I am having the same problem as you! Attached is 'testnmea.txt' which is your sentence with the checksum corrected. 'testnmea8.txt' is your original sentence. Using the VDR plugin 'testnmea' works correctly, 'testnmea8' does not, with checksum disabled. I think we have a bug in the main program.

Mike
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Old 24-10-2019, 12:30   #12
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Re: Heading info not being accepted/used

Hi Chris

Thank you for looking into this.

The actual sentence, as displayed in nmea debug, has no spaces.

Tim
Quote:
Originally Posted by Moo View Post
There is a space in before the heading in both those files. That should not be there.

Chris
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Old 25-10-2019, 12:18   #13
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Re: Heading info not being accepted/used

Apparently my autopilot unit is not new enough to enable HDG or HDT output.
So I have to continue with HDM output.
According to the O5 manual, this should work, but it isn't yet, for some reason.
So I remain hopeful that someone smarter than me will be able to help me work out if it is possible, or not.

Tim
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Old 25-10-2019, 13:30   #14
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Re: Heading info not being accepted/used

Tim..
  1. HDM is working. I use it myself. As long WMM is activated you'll get a true heading. See my shot.
  2. Your HDM sentence may have a bad or corrupt checksum. It would though be possible to omit the checksum control in OCPN.
  3. But... there is something strange with the selection "[] Control Checksum" option in OCPN connections as mentioned here.
    If I de-select the "control checksum" on a previously created connection it is again selected when I return to "Connections" tab, also as mentioned here before. Probably a bug.
    But --- If I create a new connection and de-select the "Control checksum" before I apply it the first time it's stable afterwords.
So, for a test "Remove the Connection" you now use to achieve heading data from the autopilot. -> "Apply" - "OK"
Then make a new connection with the same properties but make sure "Control Checksum" is not selected before the first "Apply" and "OK"


Send again HDM from the AP and check for example radar_pi info as of my shot.

Håkan
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Old 25-10-2019, 13:50   #15
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Re: Heading info not being accepted/used

Hakan
Thank you for your reply.
I have followed your steps suggested.
I now have Checksum staying unchecked.
I have heading info coming into O5, but it still isn't being used.
I seem to have something wrong with my sentence, maybe.

TimClick image for larger version

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