First Gen HRM-Run drops out after 2-ish mins

I think quality team they did not testing external device if works together with fenix only testing free fenix without connect any device

Drops in running dynamics data was exactly what I saw on my Fenix 5 (not +). HR would still be recorded fine but RD fields would have gaps. I could easily reproduce the issue by dropping my watch arm to my side whilst running. I ended up returning my Fenix 5 and got a 935 which worked perfectly. I’ve now sold the 935 and got an f5+. So far I’ve been unable to reproduce the issue so things are looking good. Also no issues with Stryd. I’m using one of the latest HRM-RUN devices. Happy to post versions of things if you need. Hopefully it’s just an issue with your heart rate monitors rather than your watches. Good luck both.

Did a 1hr 40min run with my old-style HRM-RUN this morning with no problems (other than my lousy running form). Here's the info on my sensor:

Model #: 1752
Man. #: Garmin
Serial #: 3963576
SW Ver: 6.60

The thing with ANT+ is that the watches don’t transmit to the sensor, they simply receive. So if the sensor is timing out, it’s not the watch that’s the problem. If there’s any way you could get your hands on another HRM Run to test, that would rule in/out the coincidence that your current pod just happened to develop a fault at the same time as changing to the new watch.

That is not 100% correct. There are plenty of things that can go wrong on the receive side as well. A register can tick over and forget the pairing. A counter can be out of bounds in the code. So just because the sensor data is no longer showing in the watch it might not be the sensors problem. Issues are NOT unknown in the different ANT+ software communications stacks. :)

/k
PS: Sitting right now and debugging ANT+ integration code on a Nordic Semi nRF52832 ANT+/BLE board.:)

kaz911 Yes, my statement was perhaps a little too black and white, as there are plenty of examples of ANT+ going from head unit (watch) to sensor: sending software updates to the HRM Run is one, controlling VIRB cameras is another. But in general use during an activity, an ANT+ sensor merrily pushes out its data for any number of receiving heads/watches to receive (in my examples here I have both F5 and F5+ receiving data from the same HRM Run strap). So it’s not like BLE where there’s a one sensor to one head unit 2 way connection thus I’d doubt very much an ANT+ sensor needs ‘feedback’ from any one of the multiple listening head units to keep it active.

As I was thinking last night about the issue people described here and recalled that when RunScribe were tweaking the ANT+ transmission profiles of their pods through a rapid succession of beta softwares, to better connect with the Fenix 5, there was one point when a number of us noticed that we were loosing RD data from the HRM Run (but not HR data) exactly at the points the data from the RunScribe pods was being received (and vice versa). With your ANT+ knowledge hat on, is there something in that to explain what folks are seeing here?

kaz911 As I was thinking last night about the issue people described here and recalled that when RunScribe were tweaking the ANT+ transmission profiles of their pods through a rapid succession of beta softwares, to better connect with the Fenix 5, there was one point when a number of us noticed that we were loosing RD data from the HRM Run (but not HR data) exactly at the points the data from the RunScribe pods was being received (and vice versa).

This is very interesting, and perhaps a relevant piece to this puzzle, as that's exactly what's happening to us.

In the interest of "science" we ran last night with a current-generation red pod HRM-Run with both the 5X and the 5 Plus and experienced the exact drop in running dynamics, at exactly the same time (minute 2:09) across 4 test runs. The HR data stream was maintained throughout.

My next step is most likely a factory reset to see what happens with a "clean" watch without any sensors beyond the HRM-Run.

I'll also throw this out there to the Stryd community and see if others are experiencing this issue.

Thanks again for the input!

But it is funny that it is at around 2:08 / 2:09 every time. 2 minutes 8 seconds - is a magic computer number in seconds - 128 tics.

So looks like it might be a signed byte counter that should have been unsigned. (Signed means it can count from -128 to +127 - where as if it had been an un-signed byte it could count from 0 to 255) - so somehow a roll over when it reaches 127 (0b01111111) and then INCrement 1 - rolling over to 0b1000000 = (minus) - 128..) - some counters do not like negative values.

The HR data stream was maintained throughout.

I'm unable to edit my post for some reason.

I wanted to add that we've seen no drops in any Stryd data during the runs where Stryd was connected, although the HRM-Run data drops even when the Stryd footpod is turned off or not present.

And one additional symptom we noticed last night is that after it drops, the dynamics screens are no longer available to view during the activity. Starting a run with the GCT balance field displayed, for example, shows the data until it drops. At that point the values are blank. If we page thru the screens, the dynamics screens no longer show at all.

I'm having the exact same problem. Fenix 5 plus sapphire with HRM Run. Two runs so far, and bothe times the running dynamics drop out after 2:08.