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Old 25-07-2015, 18:53   #1
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OCPN to Autopilot problem

Following a recent upgrade to an AIS transceiver, I am trying to get the output to my Nav-Man 3100 autopilot to work properly. So far, it will engage and begin to follow a route from OPCN, but when it reaches the first waypoint, the a/p says "end of route" and reverts to standby condition. It seems to have the location of the next wp, but does not attempt to steer towards it.

The system consists of a Vesper Vision AIS with internal GPS, linked via wifi to the computer. The computer is linked to the a/p via a com port. I have selected to output the following sentences from the offered list: HDM RMB RMCC GLL VTG APB XTE. I suspect that I might be missing something here! Incidentally, when connected to our previous GPS, a northstar 541, it worked flawlessly.

Any suggestions for changes would be welcome!

And to forestall any criticism of using the gps to drive the a/p, we very seldom use this function, but would like to have the option to do so, for it can be quite useful at times.

Cheers,

Jim
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Old 26-07-2015, 11:54   #2
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Re: OCPN to Autopilot problem

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Originally Posted by Jim Cate View Post
...............So far, it will engage and begin to follow a route from OPCN, but when it reaches the first waypoint, the a/p says "end of route" and reverts to standby condition. It seems to have the location of the next wp, but does not attempt to steer towards it. ..............................
Jim.. I think this behavior is common for most autopilots. My, although dated, has the same logic. When a WP is reached the AP beeps and goes to Auto mode, so I've to press NAV mode again, for every reached WP. I think this is due to security reasons to not alter the course unattended. This has nothing to do with OCPN, it will continue sending out the route to follow until the last WP is reached.
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Old 26-07-2015, 13:41   #3
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Re: OCPN to Autopilot problem

My AP will follow an OCPN route from the time I engage it until I manually disengage it. When it hits a WP there's a few seconds where it stays on the old course and then if it's a major course change the rudder goes to lock until we hit the new course. It can be quite alarming.

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Old 27-07-2015, 05:20   #4
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Re: OCPN to Autopilot problem

Hi,

We have a simrad TP20 the behaviour is similar. OpenCPN recognises arrival at the waypoint and switches to the next waypoint. The AP goes to navigation mode (stays on the last heading) until we re-engage nav-lock. Annoying. It is documented as a feature to avoid any significant course changes!

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Old 27-07-2015, 17:17   #5
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Re: OCPN to Autopilot problem

Bump!

Still hoping for some help here. Where are the gurus?

Jim
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Old 27-07-2015, 18:27   #6
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Re: OCPN to Autopilot problem

Jim...

Just to be clear here...
Are you attempting to follow a route setup and activated in OCPN?

OCPN would not change its autopilot output sentences if you simply changed the GPS receiver input. They are separate ports, with independent filtering. So something else has changed, probably the A/P output port filtering.

Have you looked at the A/P documentation to try to find what it is expecting, exactly? I would try fewer output sentences, starting with APB only, and see what happens.

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Old 27-07-2015, 18:56   #7
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Re: OCPN to Autopilot problem

Jim,
My autopilot is rather old, but it takes the APB sentence and steers to a heading. It does not know about routes or waypoints, so is it possible to just send APB to your autopilot and see if it will follow what OCPN is telling it?

Jon
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Old 27-07-2015, 19:02   #8
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Re: OCPN to Autopilot problem

jon...

This is exactly what I do daily. So OCPN is exclusively responsible for sending waypoints, XTE, etc. to the autopilot. No need to involve the GPS route capability.

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Old 28-07-2015, 16:58   #9
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Re: OCPN to Autopilot problem

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Originally Posted by bdbcat View Post
Jim...

Just to be clear here...
Are you attempting to follow a route setup and activated in OCPN?
*******
Yes, that is what I am attempting to do.
*****

OCPN would not change its autopilot output sentences if you simply changed the GPS receiver input. They are separate ports, with independent filtering. So something else has changed, probably the A/P output port filtering.
******
in my previous setup, oCPN was not involved. it was a stand alone GPS (Northstar) driving the a/p. This is my first attempt to involve OCPN. I understand that the input from the internal GPS in the Vesper AIS goes through a different port from the output to the a/p.
*******

Have you looked at the A/P documentation to try to find what it is expecting, exactly? I would try fewer output sentences, starting with APB only, and see what happens.
*******
The documentation says that it will accept APA APB BOD BWC MWD MWV RMA RMB RMC VHW VTG XTE. Unfortunately, it offers no advice about what it needs to function properly.

I will try limiting it to APB and see what happens.


Dave
Thanks again for the advice.

Jim
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Old 28-07-2015, 17:06   #10
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Re: OCPN to Autopilot problem

Jim, I think there is some confusion as to the specifics of your problem.

Are you saying that OCPN drives the AP fine to the first waypoint, then cancels the remainder of the route altogether when it reaches it? If this, does your AP also disconnect and go into standby?

Or are you saying that OCPN drives the AP to the first waypoint, then the AP does not automatically change heading to the next waypoint - even though OCPN shows the route actively continuing and changes itself to the next waypoint? If this, does your AP stay on the previous heading in auto mode?

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Old 28-07-2015, 18:01   #11
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Re: OCPN to Autopilot problem

Try only sending ECRMB,ECAPB to the AP.
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Old 28-07-2015, 18:11   #12
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Re: OCPN to Autopilot problem

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Jim, I think there is some confusion as to the specifics of your problem.

Are you saying that OCPN drives the AP fine to the first waypoint, then cancels the remainder of the route altogether when it reaches it? If this, does your AP also disconnect and go into standby?

Or are you saying that OCPN drives the AP to the first waypoint, then the AP does not automatically change heading to the next waypoint - even though OCPN shows the route actively continuing and changes itself to the next waypoint? If this, does your AP stay on the previous heading in auto mode?

Mark
Mark, it is the latter condition: it arrives at the first wp, the a/p sounds an alarm and displays "end of route" and goes into standby (ie, not steering at all). Meanwhile, OCPN has advanced to the next waypoint and looks completely normal.

Thanks for the reply,

Jim
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Old 29-07-2015, 06:13   #13
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Re: OCPN to Autopilot problem

Jim,

Going into standby is not an expected mode for that autopilot regardless. Even if it thought it had reached the end of a route, it should stay on the current heading until you either manually put it in compass mode or standby.

What happens if you switch OCPN to the next waypoint in a route before reaching the first one?

Mark
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Old 02-08-2015, 20:34   #14
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Re: OCPN to Autopilot problem

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Originally Posted by colemj View Post
Jim,

Going into standby is not an expected mode for that autopilot regardless. Even if it thought it had reached the end of a route, it should stay on the current heading until you either manually put it in compass mode or standby.

What happens if you switch OCPN to the next waypoint in a route before reaching the first one?

Mark
Mark, sorry to be so long in replying, but we've been stuck at anchor for a few days in the Southport Zoo and that is not conducive to experimentation!

If I manually switch to the next waypoint in Ocpn it will steer to that wp. When it arrives it shows "route ends",sends an alarm and goes into standby GPS mode.

I tried the o183 sentences suggested by Gilana and jongough and sadly the behavior did not change.

I'm kinda stymied at this point, and would love to hear any further suggestions. We expect to be at sea for the next week or so and internet will not be available. Not sure what the situation is in Noumea these days, but expect that we will be able to set something up once we arrive.

Thanks to all who have tried to help.

Jim
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Old 02-08-2015, 23:43   #15
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Re: OCPN to Autopilot problem

Jim,
Looking through the manual for the 3100 there appear to be three modes, compass, GPS & wind. In GPS mode if you have WPT AKN set on, it will raise an alarm and wait for the user, you, to acknowledge the alarm before going onto the next waypoint. Is this possibly the problem? If you send only APB messages to the unit and turn off WPT AKN does it work better or just the same?

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