PM5 bluetooth with heart rate: Loosing connection

[MarkusRowing]

Hi,
I have written an Android application that reads out a few parameters form the PM5 ergometer via bluetooth. The issue I am having is that the hearte rate information via the same bluetooth characteristic gets lost once in a while! All other parameters like stroke stroke or pace are constantly synchronized. I would expect the same for the heart rate. Does anyone have the same issue or know a solution?
By the way, my heart rate is constantly updated on the PM5 monitor. Hence, the bluetooth pairing between POLAR H7 and PM5 is working. Only sending the heart rate data via the bluetooth connection to the Android device is not working all the time. It works sometimes for 2 or 3 minutes and then it stopped. Sometimes it picks up and looses again.

Thanks for sharing your thought on what to do.

Best Regards.
Markus

[pm5hacker]

You didn't say how you were "reading" the characteristic. Bluetooth is so slow that issuing a "characteristic read" and waiting for a response may well not work consistently. All of the interesting values (including heartrate) are broadcast (Bluetooth calls it "notify") and all can be turned on during setup. In "notify" any characteristic that changes (any of its bitfields) will generate a"notify" message. On Linux, the is a command in bluetoothctl to do this. I get a new heartrate value every time it (or any of the other fields in that characteristic) changes. It's characteristic CE060032-43E5-11E4-916C-0800200C9A66, which also contains elapsed time to 10ms - so that's every half second!

You also didn't mention how your heartrate device is connected to the PM5. If it is also BLE (my Polar H9 is), one would expect occasional dropouts due to collisions. If the belt-PM5 connection drops out, the notify message will still have a value -I suspect it will be the "255" value documented as "invalid".

[Tsnor]

... By the way, my heart rate is constantly updated on the PM5 monitor. Hence, the bluetooth pairing between POLAR H7 and PM5 is working.

It's common for software to display the last good value if it can't get a new value. I would not use the PM5 display as proof that the PM5 is getting every data value from your belt.

FWIW for me the per-stroke data downloaded from C2 log (coming from ergdata from the PM5 from an H10 belt) does show dropped HR values for me, and sometimes the PM5 loses HR sync with the belt (or the belt loses synch with HR) then regains it. Other per stroke values are reported while the HR data is not. This can be also be seen clearly in the HR graphs from the C2 site on the workout details page -- the red HR trace drops to zero. The polar flow / polar beat graph of the same data at the same time does not show a drop which could be smoothing or a sign it was the PM5 that dropped the data. I'm assuming since Ergdata got the per-stroke meters etc that it was not Ergdata that dropped the HR data.

[Mark Pettit]

If you are 'loosing' connection, then I'd suggest 'tightening' it.