Problem with receiving MQTT messages in the BG96 module

IoT Modules LPWA Module
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1

Hello, I have a problem during the implementation of MQTT in the BG96 module. I establish communication with the MQTT Broker and then subscribe to a topic; During the first 5 seconds (approximately) I receive messages sent from another client, but after this time I do not receive the messages even though the communication is active.

AT+QMTOPEN=0,“test.mosquitto.org”,1883
AT+QMTCONN=0,“BG96”
AT+QMTSUB=0,1,“testtopic/mitopic”,2

2

Hi @Lera

Its hard to say without any modem log. but can you please help try with send message to MQTT server? and if server could be receive it?

4

hello @Linkin-Q

I share with you the record of the communication process with the Mosquitto broker.

[2023-11-30_16:20:13:645]AT+QPING=1,“www.google.com”
[2023-11-30_16:20:13:645]OK
[2023-11-30_16:20:14:444]
[2023-11-30_16:20:14:444]+QPING: 0,“209.85.203.105”,32,302,255
[2023-11-30_16:20:14:721]
[2023-11-30_16:20:14:721]+QPING: 0,“209.85.203.105”,32,277,255
[2023-11-30_16:20:15:069]
[2023-11-30_16:20:15:069]+QPING: 0,“209.85.203.105”,32,348,255
[2023-11-30_16:20:15:389]
[2023-11-30_16:20:15:389]+QPING: 0,“209.85.203.105”,32,320,255

[2023-11-30_16:20:15:389]+QPING: 0,4,4,0,277,348,311
[2023-11-30_16:20:20:229]AT+QMTOPEN=0,“test.mosquitto.org”,1883
[2023-11-30_16:20:20:229]OK
[2023-11-30_16:20:20:511]
[2023-11-30_16:20:20:511]+QMTOPEN: 0,0
[2023-11-30_16:20:24:726]AT+QMTCONN=0,“BG96”
[2023-11-30_16:20:24:728]OK
[2023-11-30_16:20:25:309]
[2023-11-30_16:20:25:309]+QMTCONN: 0,0,0
[2023-11-30_16:20:28:540]AT+QMTSUB=0,1,“testtopic/luis/tass2”,2
[2023-11-30_16:20:28:540]OK
[2023-11-30_16:20:28:840]
[2023-11-30_16:20:28:840]+QMTSUB: 0,1,0,2
[2023-11-30_16:20:31:712]
[2023-11-30_16:20:31:712]+QMTRECV: 0,1,“testtopic/luis/tass2”,"Hello world "
[2023-11-30_16:20:33:318]
[2023-11-30_16:20:33:318]+QMTRECV: 0,2,“testtopic/luis/tass2”,"Hello world "
[2023-11-30_16:20:36:524]
[2023-11-30_16:20:36:524]+QMTRECV: 0,3,“testtopic/luis/tass2”,"Hello world "

5

After the last message, the modem does not receive messages. This problem occurs only when I connect to LTE networks

6

Hi @Lera

Sorry for the late response. According the phenomenon you descripted, seesm after RRC released, there is no paging message from eNB, so module cant establish RRC connection, and it will be cause cannt receving downlink message but the uplink messages should be good.

Could you please help do following test to comfirm this?

  1. Connect to MQTT server;
  2. Sub topic
  3. Publish messages to MQTT server (1-2 messages should be enough)
  4. Check RRC status with AT+QCSCON? (When returned value +QCSCON: 0,0 the second 0 means in idle, RRC released)
  5. Publish message from server to Module (Cant receive DL mesage ?)
  6. If step5 cant receive DL message, then do publish message to server (I think it should be OK to send to server)
    If Step6 correct, that seems caused by eNB, because there is no paging messages from eNB, Module can not connect to network, need to check with operator.

Thanks!