Q2687 holds with CREG response 2 and constant, low CSQ

Legacy Legacy AirPrime modules
1

In my company I am using AirPrime Q2687 module. The problem occurs most probably with pure signal condition (device is moving and logs from the field are very limited) - but not always, we can reproduce this problem only in one place in the field.

What I currently know is that modem somehow “holds” for a long time with response for AT+CREG? which is 2 (not registered, ME currently searching for a new operator). Communication via this modem is also stopped. Also CSQ during this time is at constant, low value (for example 2). The only thing to repair this situation is reset and after this everything backs to the normality immediately.

For a quick workaround we could trigger reset when such behaviour is detected - I will repeat it once again: reset causes back to normal behaviour immediately, which might indicate that something is wrong with the modem which holds.

Is this problem already known and currently under investigation or maybe it exists some better workaround? Versions: firmware 7.45.1, OpenAT 6.35, WIPlib 5.41

Thanks for help!

2

https://forum.sierrawireless.com/t/undocumented-side-effect-of-at-cops-0/4871/1

3

Thanks a lot. It sounds really strange… I will try with AT+COPS=0 first and let you know if it helped…

4

Unfortunately, it did not help. AT+COPS=0 did not trigger the module back to normality. I had to reset it after some time and then of course it started to work properly.

Should this COPS=0 workaround work always or is it possible that it also doesn’t help? And the second question, which is more important for me I think, is this bug already reported to Sierra Wireless? Is it any chance that it might be corrected?