HL7802 automatic fallback to 2G

IoT Modules HL78
1

Hi,
Is the modem hl7802 fallback to 2g automatically?
I have configured the PRL as says the command interface guide using +KSELACQ:

// In mode 0, set RAT1 to 1 (CAT-M), RAT2 to 2 (NB-IoT), and RAT3 to 3 (GSM). After
manually rebooting, the module will begin scanning for CAT-M cells first. If no cells are
found, module will fallback first to NB-IoT, then GSM, then restart from the beginning of
the PRL.
AT+KSELACQ=0,1,2,3
OK

The KSRAT is set to 0 as says the guide:
0 In the Write format, =0 is used to switch to the first RAT
in the preferred RAT list (PRL), and fall back to subsequent RATS
in the PRL if cell coverage is lost. If the PRL is empty, switch to
CAT-M1. To set the PRL, see AT+KSELACQ

However when I start a communication, it seems not scan other cells but modifying manually to 2G, my equipment transmits.

The FW version is 4.6.8.0

I hope someone can help me to understand better.

Thank you!

2

Hi paulo.fischer,

There is a known issue with RAT fallback. The issue is fixed on the latest 4.6.9.4 firmware. Please update the latest firmware 4.6.9.4 to the module and retry.
You can get it here HL78xx (HL7800/HL7800-M/HL7802) Firmware

3

Thank you very much for your quick reply.
I’ll update the FW and come back with the results.
BR, Paulo.

4

Hi Donald,
I am so sorry for took so much to reply you.
I updated the modem FW but the fallback didn’t work. Talking to my IT team, now it’s something related to our device firmware that needs to be fix.
Thank you.

5

Hi paulo.fischer,

According to HL78xx - AT Commands Interface Guide - Rev16.0.pdf:
Reboot is required for the write +KSELACQ command to take effect.

Did you restart the module (AT+CFUN=1,1) after executing AT+KSELACQ=0,1,2,3 ?
Could you please share with me the full AT commands logs file?