attaching network for more than 5 minutes

[William.wei]

hi support team,

There is one problem with customer product, for modem it takes more than 5 minutes time to attach the network, i compared with DK, attach is the modem trace;

please help to check what's wrong with this device.

i believe there must be some parameter that is wrong in this device. after command "AT%CFACTORYRESET = 0", this product goes back to normal.

Regards,

William.

trace-2021-11-08T06-35-24.142Z_good_attach.pcapngtrace-2021-11-08T06-49-42.089Z_longtime_attach2.pcapng

[Håkon Alseth]

Hi,

 

The logs does not show much, in terms of what happens in the network registration status.

there is an attach request after 488 seconds, but there's no information about the link in general in the trace. Do you have a raw modem trace .bin of the issue?

i believe there must be some parameter that is wrong in this device. after command "AT%CFACTORYRESET = 0", this product goes back to normal.

Are you using AT%XBANDLOCK for instance?

 

Kind regards,

Håkon

[William.wei]

hi Hakon,

This is the log with raw format. i think bandlock is not the root cause, because i can see the network rsrp is collect very soon.

Regards,

William.

trace-2021-11-09T04-29-29.167Z.bin

[Håkon Alseth]

Hi,

 

Do you have a trace that starts from the boot time of the nRF? this trace looks like it has been started after the application has been running for a while.

 

Do you see this behavior in other samples, like at_client as well?

 

Kind regards,

Håkon

[William.wei]

hi Hakon,

this application is Serial_let_modem, this device is battery powered, and may have some repeated infor before i reinstall the battery, here is the modem trace

Thank you again.

.trace-2021-11-12T09-14-42.882Z.bin

[Håkon Alseth]

Thank you for the trace file. I have shared it with the modem team for analysis. I will get back to you within some business days with more information.

 

Kind regards,

Håkon

[Håkon Alseth]

Thank you for your patience.

 

We have reviewed the modem trace, and found that the "backoff timer" is running in this scenario:

EMM back-off timer seems to be running for the network in question due to which Attach procedure is not allowed. The start of the timer or the reason for starting it is not visible in the log. But it is visible that Attach is started immediately after the timer expires. So no errors.

 

Kind regards,

Håkon

[William.wei]

hi Hakon,

this parameter is not set by customer, and 91 module is  totally factory setting statues.

may i ask what's the API for back-off timer? i can't image where it comes from, customer tested after command "AT%CFACTORYRESET = 0", this module goes to normal.

Regards,

William.

[Håkon Alseth]

Hi William,

 

William.wei said:

this parameter is not set by customer, and 91 module is  totally factory setting statues.

may i ask what's the API for back-off timer? i can't image where it comes from, customer tested after command "AT%CFACTORYRESET = 0", this module goes to normal.

This is a timer that is initiated by the cell tower. If you search for "emm back-off timer", you will find more information on how this works.

However, we do not see the start of this back-off timer or the reason for it, as the log did not show this.

 

Kind regards,

Håkon