MQTT return ERROR after 24 hours

[RobertT]

Hello!

 I am sending MQTT commands over UART from an NRF52840 DK to the NRF9160 DK which has the ibasis sim card inside. I noticed 3 times so far that after 24 hours , 1 hour tolerance, I get only  ERROR messages returned after sending the MQTT commands with the payload.  Basically I need to reset the NRF52840 DK and  re-send all the MQTT commands for connecting to the MQTT broker, autenthificating, opening connection and initialising the modem ( AT+CFUN = 1 etc) .

 I was wondering if there were previous experiences like this.  I did use an osciloscope and the NRF52840 DK is sending the right commands with the good payload over UART even after 24 hours, it's just like the modem closes the connection or something...

All the best,

Robert.

[Carl Richard]

Hi again!

Understood. This means that the nRF9160 itself likely has crashed. If it happens to all modems it's not a faulty device at least, and more likely a bug in the code/modem. We just released a new modem version (v1.3.0), so you could look into upgrading one of the devices to see if that makes a difference as well. Looking forward to new results with a different SIM!

In order to monitor the on site device you must either save relevant information to the flash, so that it can be read out afterward or have it connected to a computer for UART logging. Given that the same issues arise from the device connected to your computer I think the best approach is to get the logs and trace from that device first.

I've spoken with the engineer that have taken your other case and we've agreed that he will follow you up further, if that's okay for you. However, I'll leave this case open and I will monitor the other case so that I can assist when necessary.

Best regards,
Carl Richard

[RobertT]

An update: 

- last week I got the new O2 sim card ( for IoT ) and took the set up I had on site and brought it on the bench ( nrf52840 dk communicating over uart to nrf9160 dk ) . Did not change anything on it except for the sim card.

 - I am now into the 5th day of the system running continuously without issues. 

A next step would be to get the same set up with O2 sim card on site and see how it behaves in that area or put the O2 sim card into another set up like this ( just different devices )  on the bench. I will do one of them this week and let you know again what happened.

All the best,

Robert.

[Carl Richard]

Hi, Robert!

Thank you for the update! It's great to hear that things seemingly are running better and more reliable now. However, I don't like the fact that it misbehaves to the degree we have seen here with bad reception. Hopefully a modem trace could give some information as well!

Best regards,
Carl Richard