AT-COPS mode changes from 0 to 2 | Telit Cinterion IoT Developer Community
March 9, 2018 - 2:02pm, 9489 views
Hi!
We use Aplicom TRIX A9 device with EHS5-E module. In our application, we need a connection to server available all the time, if only possible (the device is moving, it's a fleet monitoring app).
1) However, we observe weird behavior - occasionally (in regions where network coverage is poor) the modem permanently stops trying to register to the network.
We send AT+COPS? command periodically to monitor the mode - it goes from 0 to 2 (we never set it to 2 on our own), and in order to *********** to the network again, it is necessary to send AT+COPS=0 again (note, that we prefer to use automatic mode).
Is it expected behavior? Any way to prevent it? Under what conditions does the modem go into COPS mode 2 on its own?
2) In our monitoring code I ovserve, that AT+COPS? returns mode 2 which means it's not searching for a network, and at the same time AT+CREG? returns status 2, which means it actually does. I consider those results self-contradcitory.
Is it a known bug?
BR
Hello,
Please try to disconnect the antenna or put the device int shield box if necessary - you'll see "+COPS: 2" immediately after the network is lost. When you connect the antenna back the module should register again. So in that case it does not mean that the module was manually deregistered.
"AT+CREG?" command will return "+CREG: X,2" which means that the module actually is searching for a network. But it is not searching constantly - there is some algorithm for periodic searching and the delay may be increased.
In case of manual deregistration with "AT+COPS=2" the command "AT+CREG?" will be showing "+CREG: X,0" which means that the module is not searching.
So if there is such a poor coverage that the module looses network for longer is it really not able to register again if the signal becomes much better?
I think that in your case triggering the automatic network registration might help to speed-up the registration.
Regards,
Bartłomiej
Hi!
1) If COPS mode = 2 doesn't mean permanent deregister, then the official documentation is perfectly misleading, as it states (ehs5-e_atc_v03001.pdf, page 161) the following:
"2 Manually deregister from network and remain unregistered until <mode>=0 or 1 or 4 is selected.[..]"
2) We observe getting int o COPS=2 state in the field. The device is moving back into area of perfect radio coverage, but never registers back again, unless AT+COPS=0 is issued. We observe it staying in COPS mode 2 for many hours, unless manually forced to register again.
3) As of COPS vs CREG - we see COPS mode = 2 and CREG status = 2 at the same time, in the field.
BR,
Przemyslaw
Hello,
I agree that COPS output may be misleading in this situation. But CREG can help to verify if the network registration status.
Hopefully there is a workaround that you have found with triggering a registration with AT+COPS=0 command if the module is not registered for a longer period.
You could try to check if there is any error report available when such a situation happens with AT+CEER command. But please reset it first by sending AT+CEER=0.
Are you using roaming? Please also check the firmware version with ATI1 to see if there is any update available.
Regards,
Bartłomiej