BG95-M2 AT+CEREG fails, no URC but AT+QNWINFO sais connected

IoT Modules LPWA Module
1

Hello. From time to time I am experiencing a strange error with the BG95-M2 module. I am using it as a radio modem, controlled via UART by a host processor. After configuring the modem, i check the connection state manually once and then wait for the CEREG URC. However, sometimes the manually requested AT+CEREG sais there is no connection, but AT+QNINFO sais there is connection. There is also no URC for over 1 minute after the start. This is the log:

10013   command: AT+CGMM
10014   message: AT+CGMM
10015   message: BG95-M2
10015   message: OK
10016   command: ATE0
10017   message: ATE0
10017   message: OK
10018   command: AT+QSCLK=0
10023   message: OK
10025   command: AT+QURCCFG="urcport","uart1"
10027   message: OK
10028   command: AT+CPIN?
10030   message: +CPIN: READY
10030   message: OK
10031   command: AT+CIMI
10034   message: ---cimi---
10034   message: OK
10035   command: AT+CREG=0
10036   message: OK
10037   command: AT+CEREG=2
10039   message: OK
10040   command: AT+COPS=0
10049   message: OK
10051   command: AT+CPSMS=0
10053   message: OK
10055   command: AT+CEDRXS=0,5
10056   message: OK
10057   command: AT+CEREG?
10059   message: +CEREG: 2,2
10060   message: OK
10061   command: AT+CREG?
10063   message: +CREG: 0,2
10063   message: OK
10064   command: AT+QNWINFO
10069   message: +QNWINFO: "NBIoT","26201","LTE BAND 8",3739
10070   message: OK
2

pls run
AT+QENG=“servingcell”

3

Same issue:

10471	command: AT+CGMM
10473	message: AT+CGMM
10473	message: BG95-M2
10474	message: OK
10474	command: ATE0
10476	message: ATE0
10476	message: OK
10477	command: AT+QSCLK=0
10481	message: OK
10484	command: AT+QURCCFG="urcport","uart1"
10485	message: OK
10486	command: AT+CPIN?
10488	message: +CPIN: READY
10489	message: OK
10489	command: AT+CIMI
10492	message: ---<cimi>---
10492	message: OK
10494	command: AT+CREG=0
10495	message: OK
10496	command: AT+CEREG=2
10498	message: OK
10498	command: AT+COPS=0
10509	message: OK
10510	command: AT+CPSMS=0
10512	message: OK
10514	command: AT+CEDRXS=0,5
10515	message: OK
10518	command: AT+QICFG="dataformat",1,1
10519	message: OK
10520	command: AT+CEREG?
10522	message: +CEREG: 2,2
10523	message: OK
10523	command: AT+CREG?
10533	message: +CREG: 0,2
10534	message: OK
10535	command: AT+QNWINFO
10540	message: +QNWINFO: "NBIoT","26201","LTE BAND 8",3739
10540	message: OK
10542	command: AT+QENG="servingcell"
10548	message: +QENG: "servingcell","LIMSRV","NBIoT","FDD",,,,,,,,,,,,,,
10549	message: OK

This issue does not happen all the time however. To reproduce it, i had to try 3 to 4 times.

4

LIMSRV indicates that the terminal registration network has been denied and you need to check
1)Check whether the SIM card service is normal
2)Whether you have configured APN

5

As per TCP/IP application note, SIM Card service is checked by AT+CPIN and, APN is only configured after successful connection to the ps service.

grafik
grafik709×740 68.7 KB

You can see the successful commands in order of the flow chart in the logs above. Should that be changed?

6

This reference process is only for your reference, I suggest you can execute AT+CGDCONT or AT+QICSGP to configure APN