Cannot find network with some HL7688 modules

IoT Modules
1

Hello,
We are using the HL7688 module for our Embedded devices and we are able to successfully make data transfer ore create a PDP session and use it.
But it is not the same case for all the purchased HL7688. We have found some of the modules are not able to connect to networks with the same setup when we just replace the HL7688 modules and we get following information from AT commands execution.

AT+COPS=?
+CME ERROR: not found
AT+COPS=0
+CME ERROR: no network service

But when we change the module there is no problem. Can any of you help us identify what is th e problem?

2

Hi,
Could you help to check these values:

  • ATi10
  • AT*PSRDBS?
  • AT+CMEE?
  • AT+CGDCONT?

I guess that these modules are not set correct band, so they can not detect any network.
Please set all bands for these modules ( or set correct network band), ex: AT*PSRDBS=1,315584

Thanks,

3

Hello Jerdung,

Thanks for your quick reply, I appreciate it.

Please check the following results for the non-working module.

ATi10
Modem-Firmware:
RHL7688.A.2.15.1.0.151600.201809181425.x7160_1
HL7688
HL7688.A.2.15.1.0
x7160
FUSED
2018-09-18 17:14:50
r12946

Primary-Boot:
RHL7688.A.2.15.1.0.0202170420.201809181425.x7160_1
2018-09-18 14:25:00
r10178

Secondary-Boot:
RHL7688.A.2.15.1.0.0202170420.201809181425.x7160_1
2018-09-18 14:25:00
r10178

Update-Agent:
RHL7688.A.2.15.1.0.0201160412.201809181425.x7160_1
2018-09-18 14:25:00
r12946

4G-Firmware:
7160.S3.561.40.4.805.01.5227.18265

3G-Firmware:
202.999.623.43-54.35

OK

AT*PSRDBS?
*PSRDBS: 315584

OK

AT+CMEE?
+CMEE: 2

OK

AT+CGDCONT?
+CGDCONT: 1,“IP”,"",“0.0.0.0”,0,0

OK

From the above results, it seems like the bands are already set to 315584. Please let me know if there are any other things I could potentially check to figure out what the problem is.

I tried more AT commands to debug further and found that on non working modules I get the following.
AT+KBND?
+KBND: 00000000

OK
AT+KBND=?
+KBND: (0,20,40,800,2000,4000,10000,20000)

OK
AT+CGREG?
+CGREG: 0,4

OK

Thanks

4

Hi @Harishk07,

What location/country are you using the module? Also what carrier and APN do you plan to test the module with?
For the working module, does it have the same firmware, band setting? Can you send us the output of below commands for the working module:

  • ATi10
  • AT*PSRDBS?
  • AT+CMEE?
  • AT+CGDCONT?
  • AT+COPS?
  • AT+KBND?
  • AT+COPS=?
  • AT+CREG?
  • AT+CEREG?
5

Hello,

I am using the module in USA (EST) with the AT&T network. The APN for the AT&T network that I use is " broadband".
The firmware is same for both the modules. A.2.15.1.XXX.

Please check the output of the working module on the same setup.

Ati10
Modem-Firmware:
RHL7688.A.2.15.1.0.151600.201809181425.x7160_1
HL7688
HL7688.A.2.15.1.0
x7160
FUSED
2018-09-18 17:14:50
r12946

Primary-Boot:
RHL7688.A.2.15.1.0.0202170420.201809181425.x7160_1
2018-09-18 14:25:00
r10178

Secondary-Boot:
RHL7688.A.2.15.1.0.0202170420.201809181425.x7160_1
2018-09-18 14:25:00
r10178

Update-Agent:
RHL7688.A.2.15.1.0.0201160412.201809181425.x7160_1
2018-09-18 14:25:00
r12946

4G-Firmware:
7160.S3.561.40.4.805.01.5227.18265

3G-Firmware:
202.999.623.43-54.35

OK

AT*PSRDBS?
*PSRDBS: 315584

OK

AT+CMEE?
+CMEE: 2

OK

AT+CGDCONT?
+CGDCONT: 1,“IP”,“broadband”,“10.120.89.21”,0,0,0,0,0,0

OK

AT+COPS?
+COPS: 0,0,“AT&T”,7

OK

AT+KBND?
+KBND: 00000800

OK

AT+COPS=?
+COPS: (2,“AT&T”,“AT&T”,“310410”,7),(1,“AT&T”,“AT&T”,“310410”,2),(1,“Verizon”,“Verizon”,“311480”,7),(1,"","",“313100”,7),(1,"","",“310830”,7),(1,“T-Mobile”,“T-Mobile”,“310260”,2),(1,"","",“312530”,7),(1,"","",“311882”,7),(1,“Sprint”,“Sprint”,“310120”,7)

OK

AT+CREG?
+CREG: 2,1,“32C1”,“0B992008”,7

OK

AT+CEREG?
+CEREG: 0,1

OK

Please let me know if I can provide you with more information for debugging this issue.

6

Thank you @Harishk07.
For the non-working module, can you try to set the APN and give it a try:
AT+CGDCONT=1,“IPv4v6”,“broadband”
AT+CFUN=4
AT+CFUN=1

Let me know if this helps.

7

Thank you,
It did fix the problem. Can please help me understand how changing the IPv4v6 fixed the problem?

8

Hi @Harishk07,
I think the solution was to set the APN. Using “IP” or “IPv4v6” should work.
I usually recommend “IPv4v6” because it handles dual IP stack UE capability.
-Mihir.

9

Thank you!!!
I will change our code to use “IPV4V6” instead of “IP” which is the default.