ANT Forum

Hi,

I'm trying out continuous scanning mode for my application. It's working on my machine with two different USB sticks (Suunto mini & Elite usb2), on Linux, Windows and OS X (3 different computers).
I've sent a build to one of our users, but continuous scanning mode does not work on his machine. He is using a Mac and the Garmin USB-m stick. Our application does not use any of the ANT SDKs (when we started, there was no Linux SDK), but just straight ANT messages over USB.

A trace of the ANT messages is below:


Everything seems to be working fine, scanning mode is started:


But directly after that, this message comes:

after which the channel is closed by the stick. In the ANT Protocol document, I cannot find the reason for getting this message and also cannot find what it means. As channel is 0xFF, it's probably meant for all channels, right?

Help is very much appreciated!
Thank you,
Ilja Booij
BigRingVR.com      

Update

I have just received a Garmin USB-m stick and tried that here. It simply works as it should. That makes the problem even more interesting.

thanks for reading,
Ilja Booij
BigRingVR.com      

Has your user indicated how the USB stick is connected to the computer? We have found that USB hubs/extension cables can have serious impacts on the USB data flow and reliability of the device.      

Hi,

I'll ask him. I'll be visiting him this weekend, so I can check this and also use some other sticks and my own computer to cross check what works and what doesn't. I'll report back after that.

thanks for responding,
Ilja      

Well, that was weird. I tested on his machine with my USB sticks (Garmin USB-m and Suunto Moovestick mini). Both worked without a problem. His Garmin USB-m stick in my computer did not work, Scanning channel was closed by the stick.

So.. it seems that this particular USB-m stick is at fault. I checked the markings on the back (FCC id, other numbers there) and they were identical to those on my stick. My feeling is that his Garmin stick is defective, but I don't know if I should treat this as an isolated incident or that this will happen more often. Any advice?

Regards,
Ilja Booij      

Hi,

we're still having the same problem with the ANT stick, but for a very limited number of users. The problem is actually pretty weird. I have the problem on none of my computers with none of my ANT sticks (Garmin USB-m, Elite and Suunto Moovestick). We have some users on Garmin USB-m for which the problem stated above occurs.

The weirdest one is a user who has a 2moso ANT stick (probably just a rebranded Garmin/Dynastream?). This just works on Mac OS X, but on Windows 10, the connection is immediately closed after having opened Continuous Scanning Mode. The fact that things work on OS X rules out the fact that the stick is the problem, but I'm having trouble to see what can be the problem.

Could this be hardware related, output voltage of the USB port perhaps? To whom can I address questions like these?

Our software seems to work a lot better using Continuous Scanning Mode, as we have less problems with interference from WiFi, but we'd really like to solve this issue.

Thank you,
Ilja Booij
BigRIngVR
     

Hi Ilja,

It does sound potentially like a hardware problem ala output voltage. Do you happen to have any of these potentially defective devices on hand? It would also be interesting to get the Version Message string from the device using the Request Version command.

At least for the USB-m sticks you could try the background scan, as high duty search means they will perform similarly to continuous scan mode.

Best regards,
Harrison      

Hi Harrison,

I can sometimes reproduce the issue here on my MacBook Pro, with a Garmin USB-m stick. I have been trying to reproduce it this evening, but so far have not succeeded in getting the error again. However, I did experience it yesterday, and the code has not changed in between..

The version response I'm getting is "AJK2.07RAF"

What do you mean exactly by this last paragraph:

At least for the USB-m sticks you could try the background scan, as high duty search means they will perform similarly to continuous scan mode.

Thank you,
Ilja
BigRingVR

     

Update:

I've managed to implement a work-around: If the continuous scanning channel is closed unexpectedly (like in this case), we simply go through the assigning, setting channel frequency, enabling extended message and opening of the channel again. The nice (but strange) thing is that it always works the second time.

It would still be interesting to know what the/my real error is of course.

Thank you,
Ilja Booij
BigRingVR Team      

Any updates or solutions on this?
I have the exactly same issue. What does cause the problem? How to solve it?
Thanks.
     

We're still using the same workaround. If the channel is closed unexpectedly, we reopen and try again and that works. We've not encountered the issue anymore after implementing it this way.      

Thanks for the reply. That's probably the only solution at the moment.
It would still be nice to get a better understanding of the problem. Maybe it can be addressed from the ANT layer itself.