RE: nrf9160 PLMN selection

Øyvind — Tue, 09 Jan 2024 14:16:49 GMT

Stuart, it seems that your device is stuck in a reset loop (click here) , which restricts the device from connecting to network at all. You can subscribe to modem event AT%MDMEV=1 which will tell if Reset Loop Restriction prevents operation. Modem selects network 302 220 but that is because it is the last network UE has been registered to.

RE: nrf9160 PLMN selection

shamilton — Mon, 08 Jan 2024 18:00:34 GMT

Hi Øyvind,

I don't have the exact application log that corresponds to the modem trace, but I have a very similar one:

[00:00:00.881,134] <dbg> lte_lc: init_and_config: System mode (5) and preference (0) configured
[00:00:01.031,127] <inf> app_event_manager: e:logger_module_event LOGGER_EVT_READY
[00:00:01.967,041] <inf> app_event_manager: e:logger_module_event LOGGER_EVT_PERIODIC_TASKS
[00:00:28.696,166] <dbg> lte_lc: at_handler_cereg: +CEREG notification: +CEREG: 2,"6298","034684C0",9
[00:00:28.706,054] <dbg> lte_lc_helpers: parse_cereg: Network registration status: 2
[00:00:28.714,172] <dbg> lte_lc_helpers: parse_cereg: LTE mode: 9
[00:00:28.720,672] <dbg> lte_lc_helpers: event_handler_list_dispatch: Dispatching event: type=0
[00:00:28.729,736] <dbg> lte_lc_helpers: event_handler_list_dispatch:  - handler=0x0004470D
[00:00:28.738,891] <dbg> lte_lc_helpers: event_handler_list_dispatch:  - handler=0x0002C949
[00:00:28.747,589] <dbg> lte_lc_helpers: event_handler_list_dispatch: Done
[00:00:28.754,852] <dbg> lte_lc_helpers: event_handler_list_dispatch: Dispatching event: type=4
[00:00:28.763,916] <dbg> lte_lc_helpers: event_handler_list_dispatch:  - handler=0x0004470D
[00:00:28.772,644] <dbg> lte_lc_helpers: event_handler_list_dispatch:  - handler=0x0002C949
[00:00:28.781,372] <dbg> lte_lc_helpers: event_handler_list_dispatch: Done
[00:00:28.788,665] <dbg> lte_lc_helpers: event_handler_list_dispatch: Dispatching event: type=5
[00:00:28.797,729] <dbg> lte_lc_helpers: event_handler_list_dispatch:  - handler=0x0004470D
[00:00:28.806,488] <dbg> lte_lc_helpers: event_handler_list_dispatch:  - handler=0x0002C949
[00:00:28.815,216] <inf> cloud: Active LTE mode changed: NB-IoT
[00:00:28.821,502] <dbg> lte_lc_helpers: event_handler_list_dispatch: Done
[00:00:29.192,291] <dbg> lte_lc: at_handler_cscon: +CSCON notification
[00:00:29.199,249] <dbg> lte_lc_helpers: event_handler_list_dispatch: Dispatching event: type=3
[00:00:29.208,282] <dbg> lte_lc_helpers: event_handler_list_dispatch:  - handler=0x0004470D
[00:00:29.217,010] <dbg> lte_lc_helpers: event_handler_list_dispatch:  - handler=0x0002C949
[00:00:29.225,738] <inf> cloud: RRC mode: Connected
[00:00:29.231,018] <dbg> lte_lc_helpers: event_handler_list_dispatch: Done
[00:00:30.283,752] <inf> app_event_manager: e:gnss_module_event GNSS_EVT_WORKER_HEARTBEAT
[00:01:00.283,782] <inf> app_event_manager: e:gnss_module_event GNSS_EVT_WORKER_HEARTBEAT
[00:01:01.967,041] <inf> app_event_manager: e:logger_module_event LOGGER_EVT_PERIODIC_TASKS

The modem trace was run for around a minute and the difference from this application log is that it tried twice in a row to register to the network with MCC:302, MNC:220, TAC:25240 (Telus). Then the application firmware hangs since we are waiting for lte_lc_connect() and the PLMN is not switching to the network here that works: MCC:302. MNC: 720, TAC: 48613 (Rogers).

Regards,

Stuart

RE: nrf9160 PLMN selection

Øyvind — Mon, 08 Jan 2024 09:57:04 GMT

Thanks Stuart! Can you please provide what network you are trying to connect? How long did you run the modem trace? Do you have any application logs during this time as well?

RE: nrf9160 PLMN selection

shamilton — Fri, 05 Jan 2024 23:57:01 GMT

Hi Øyvind,

I have a modem trace attached which is captured after a reset of the board and the modem tries to register to the NB-IoT network which does not work for us. It hangs after that and doesn't try to connect to the other PLMN in the area that does work.

devzone.nordicsemi.com/.../trace_2D00_2024_2D00_01_2D00_05T22_2D00_57_2D00_56.616Z.mtrace

Thanks,

Stuart

RE: nrf9160 PLMN selection

Øyvind — Fri, 05 Jan 2024 10:55:13 GMT

Hi Stuat,

are you able to provide us with a modem trace? This way we can see exactly why the modem keeps retrying the same PLMN.

Kind regards,
Øyvind