We face the issue that in the above configuration sometimes the modem seems to reset during an active connection. The modem is then not accessible with the configured baud rate of 921600 anymore but answers to AT commands at 115200.
As well supply pins as power key and reset had been monitored with an oscilloscope, and nothing happens there in case of the malfunction.
I have two questions:
Is this behaviour already known?
Is there an AT command that lets you read diagnostic information like “last reset reason” or similar?
Hi jos, thanks for your question
If the baud rate is not saved after setting, it will become the default baud rate (115200) after restarting. If you want to save the changed baud rate, you can use AT+IPR=921600;&W to complete (AT There is a detailed description of this instruction in the manual).
If you want to know the cause of the last error, you can use the AT+CEER command to query. The explanation of the corresponding value can be found in the AT manual, thank you.
Hello Duncan,
Thank you very much for your reply.
We know about the the baudrate being reset to default after restarting, but the PPP connection is lost and the baudrate is at 115200 without doing an actual restart. This leads us to the conclusion, that the modem restarts itself.
If I understand right, +CEER will just return the error in case of a connection drop without a restart, but nevertheless I’ll give it a try.
Regards, Johannes
Hello Duncan,
Mark from Quectel Germany reached out to me, but nevertheless here’s the result of using +CEER in case of error:
AT+CEER
+CEER: 5,29
OK
This is reproducable: Each time the active connection suddenly stops, the baudrate and echo settings revert to 115200, “echo on” (from configured 921600, “echo off”) and AT+CEER returns “5,29” which should mean “PSLTE cause, User Authentication failed”.
Perhaps the modem has problems switching protocol/net from GPRS (EDGE) to LTE?