XT let me down

Having Garmin zumo XT problems? there is loads of help and advice in this forum
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axamax
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XT let me down

Post by axamax »

My XT let me down yesterday. While trying to get out of Frankfurt to go to Calais I missed a turn and the XT came back with cannot calculate route.
The night before it had calculated the route no problem. That morning it calculated that morning.
I thankfully had my older XT with me and that got me going.
I have just had a look at the XTand it appears to be trying to send me to somewhere in the atlantic ocean.
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Peobody
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Re: XT let me down

Post by Peobody »

I don't have an explanation but this reminds of an instance when a road closure recalc resulted in a bunch of random route points being created with direct routing between them. It crisscrossed through farm fields and woodlands. I had the route's track showing on the map so was able to stop the route, manually navigate to beyond the road closure, then restart the route.
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axamax
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Re: XT let me down

Post by axamax »

I tried a few times during the trip but it still couldn't recalculate.
It had been sending me on a few obscure diversions on the last few days, turning me off the autobahn the exit before my scheduled fuel stop and taking me down ever narrower lanes until I "skipped" the fuel stop.
jfheath
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Re: XT let me down

Post by jfheath »

If you look at the top part of this route, I think I can give a hint at what is going on.

The top point of each of those magenta lines - if you took a pencil and draw a line through them, that is probably your intended route?

I have seen this sort of thing before with a route that was plotted on a road that the Zumo didn't know about:

A new bypass. A route consist of your route points. It also has hundreds and hundreds of invisible 'ghost' points , which the Zumo has placed there. These are a few metres apart and the Zumo joins them together with straight lines to form the magenta route that follows the twists and turns of the road. Zoom in close enough you will see that any route is not curved, but a series of short straight lines.

When a route points is plotted in the middle of a field (by accident), the Zumo will visit it by plotting a straight line to it from the point on a road that is closest - at right angles to the road that it is travelling. If a whole route is plotted in the middle of a field (because as far as the Zumo is concerned, that road doesn't exist), it will calculate a route using a nearby road that does exist and when it gets as close as it can to the plotted point it will draw a straight line to that point. And then go back to the road that does exist.

How can it plot a route on a road that doesn't exist ?

Well one way is to plan a route using a new map (that contains the new by pass), and then send it to the Zumo which hasn't got the newer map installed. As far as the Zumo is concerned my route points are all in the middle of an open field. It has to visit each point in turn - but it has to do so along nearby roads that it CAN navigate, and then makes a straight line to the route point across the field.

The result looks similar to your screen shot. But it is not identical.

Your screen shot doesn't make sense until you consider the possibility that that single via point in the middle of the atlantic may be a lot of via points all plotted in the same place. If you think of it like that - then it looks similar to what I was trying to describe above.

Why so many via points all in the same place ? I don't know.

I can offer suggestions which may be relevant.

Some route planning software doesn't know about via points and shaping points. Mapsource is one. If you load a mapsource route, into any Zumo from the 590 onwards, it will have lots of via points in it. Other software that generates routes from (say) tracks, or from (say) google maps have a similar result.

Why a lot of via points in the same place ? I have really got no idea, but modern Zumos do alter the location of your route points when they receive them. I believe that this is so that routes created on other mapping software can still be processed to obtain a reasonable route. For example, you place a point in (say) Basecamp. It is not accurately placed and is actually a few 10s of metres in an adjacent field. On import the Zumo will look at the coordinates, find a known point nearby, look up its name and substitute that point for the one that you plotted. This can be seen in Zumos since the 595 when many route points have had their name changed, and their location is slightly adjusted.

I wondered if that point was on an island, but I cannot see one in that area. The point seems to be around the equator - made me wonder if it was 0,0 or something like that.

Absolutely anything is possible if
  • The maps on the Zumo are not identical to the maps in the route planning software. Only Basecamp and Tread can guarantee that.
  • Two maps are turned on in Zumo's myMaps that cover the same area.
  • Route points are not accurately placed
  • Your mouse has a dodgy microswitch under the button - dropping a point without you noticing.
I would be very intrigued to see the gpx file for this route.
It would also be useful if you can shed any light on what you might have done to create this issue eg what software did you use, what maps, was it converted from a track, from another route. Anything would help.

As I said numerous times, at the moment I really do not know. I have ideas which may be relevant or completely wide of the mark. I'm taking the trouble to write these down because someone else may be have other snippets that will help us to home in on the cause of this. This is how we cracked the RUT issue. So next time we see the same thing there will be a number of us that can say very knowledgeably - 'Ah yes, that is because you went to make a cup of coffee half way through planning your route, and while you were gone the cat walked across your keyboard.'
Have owned Zumo 550, 660 == Now have Zumo XT2, XT, 595, 590, Headache
Use Basecamp (mainly), MyRouteApp (sometimes), Competent with Tread for XT2, Can use Explore for XT - but it offers nothing that I want !

Links: Zumo 590/5 & BC . . . Zumo XT & BC
Scottnet
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Re: XT let me down

Post by Scottnet »

My simple explanation is its software bug/memory leak. If you shut down and restart the unit by holding down the power button it should work as normal after that

This happens often to me and a restart always fixes it

Garmin are aware of this but not doing anything about it.
jfheath
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Re: XT let me down

Post by jfheath »

Scottnet wrote: Wed Aug 14, 2024 3:50 pm My simple explanation is its software bug/memory leak. If you shut down and restart the unit by holding down the power button it should work as normal after that
Nothing wrong with that as a possibility either. I have observed most of my Zumos exhibiting the characteristics of a memory leak.

For anyone that doesn't know - a memory leak is a particuar variety of poor programming. When a particular operation in a computer needs to perform a particular operation, the programmer has to assign a chunk of memory to the job. Once the job has finished and the result obtained, that memory needs to be freed up so that another section of the program can use it.

Sometimes, the job finishes without it carrying out the instruction to free up memory. Maybe the user interrupted the program before it had finished, and the programmer hadn't anticipated that. Whatever - that memory is still reserved for a program that isn't using it - and it never gets freed up. If that happens a few times, there is no more memory left - (It has leaked away). The program gets slower and slower and weird things start happening.

A reboot resets everything.

But what I saw was characteristic of a few other reasons.

Here is a quote from my own comment.
jfheath wrote: Wed Aug 14, 2024 5:38 am When a route points is plotted in the middle of a field (by accident), the Zumo will visit it by plotting a straight line to it from the point on a road that is closest - at right angles to the road that it is travelling. If a whole route is plotted in the middle of a field (because as far as the Zumo is concerned, that road doesn't exist), it will calculate a route using a nearby road that does exist and when it gets as close as it can to the plotted point it will draw a straight line to that point. And then go back to the road that does exist.
And here is an illustration of a route plotted along a new road that the Zumo map does not know about. The road is a replacement for the old A82 that runs alongside loch ness. The Zumo map does not yet know about this new A82 by pass - which on my map takes a straight line down the middle of loch ness, built on stilts. Apologies for the make believe sitaution - it was the easiest way to make sure that no other roads could get involved in the routing !!

A82 By-pass.png
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I'd still like to see the gpx file of that route if that is possible please @axamax
Have owned Zumo 550, 660 == Now have Zumo XT2, XT, 595, 590, Headache
Use Basecamp (mainly), MyRouteApp (sometimes), Competent with Tread for XT2, Can use Explore for XT - but it offers nothing that I want !

Links: Zumo 590/5 & BC . . . Zumo XT & BC
axamax
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Re: XT let me down

Post by axamax »

Sorry I'd already deleted the data when I saw your post. I'm going to try a factory reset.
jfheath
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Re: XT let me down

Post by jfheath »

Recycle bin ?
Have owned Zumo 550, 660 == Now have Zumo XT2, XT, 595, 590, Headache
Use Basecamp (mainly), MyRouteApp (sometimes), Competent with Tread for XT2, Can use Explore for XT - but it offers nothing that I want !

Links: Zumo 590/5 & BC . . . Zumo XT & BC
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