Cannot enter to PSM mode

IoT Modules LPWA Module
1

Hi,

I use BG95-M3, I configured the PSM TAU to 1 minute and RAT to 30 seconds using the following AT commands. However, after waiting for several minutes, nothing happens. psm/urc is 1. Then I execute AT+QCFG=“psm/enter”,1 to force an immediate entry into PSM, there is still no output, and I do not see the “PSM POWER DOWN” message. Furthermore, the PSM_IND pin is consistently high.

-> AT+QCFG="psm/urc",1
OK

-> AT+CPSMS=1,,,"01111110","00001111"
OK

-> AT+CPSMS?
+CPSMS: 1,,,"01111110","00001111"

-> AT+QCFG="psm/enter",1
OK

-> AT+QPSMCFG?
+QPSMCFG: 20,4

Additionally I tried changing the PSM version to 2 (in another topic somebody recommended doing so), it didn’t have any effect too:

-> AT+QPSMCFG=20,2
OK

Thank you

2

Hello @MHD

for PSM to work it needs to be supported by the network. And in my experience the network seldom accepts the exact values requested.

Below are the AT commands I am using successfully with my BG95-M3.
(Please note: I am using the Quectel specific AT commands for PSM, eq QPx instead of CPx.)

// Disable PSM
AT+QPSMS=
  OK
// Check PSM - 0 means disabled
AT+QPSMS?
  +QPSMS: 0,,,"14400","20"
  OK
// Enable PSM - ask for 60 s TAU and 30 s active timer
AT+QPSMS=1,,,"01111110","00001111"
  OK
// Check PSM - network agreed to 42 min TAU and 32 s active timer
AT+QPSMS?
  +QPSMS: 1,,,"2520","32"
  OK
// about 32 seconds later modem goes into PSM
  PSM POWER DOWN

Notes:

  • forcing PSM with AT+QCFG="psm/enter",1 does not work for me
  • when the modem is in PSM PSM_IND goes low
  • when the modem is in PSM the netlight also turns off

Thanks
Felix

3

Hello @felmue ,

Thank you for your answer. I get this result when I use your AT commands:

AT+QPSMS=
  OK

AT+QPSMS?
  +QPSMS: 0,,,,
  OK

AT+QPSMS=1,,,"01111110","00001111"
  OK

AT+QPSMS?
  +QPSMS: 1,,,,
  OK

It doesn’t show the accepted numbers. Nothing happens after this. Is it the network problem? if they are not supporting PSM, how can I save the power? I only send data, I don’t receive anything.
Can this approach replace PSM? AT+CFUN=0 and AT+CFUN=1 . Sometimes it takes a long time to connect to a network after this kind of power saving.

4

Hello @MHD

I am not an expert, but yes, I think not getting those values back means PSM is not supported by the network provider.

And yes, going the AT+CFUN route is a way to save energy.

That said, you could also look into Sleep Mode which is enabled by AT+QSCLK=1 (disabled by AT+QSCLK0) and then activated / deactivated via DTR line.

Another option is to turn the modem off completely either using AT+QPOWD or PWRKEY and then PWRKEY again to turn it on.

Thanks
Felix

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