nRF9160 dk can still be interact and not detached to network while in PSM

Question

Hello everyone, 
 I'm using nRF9160 DK with hardware version SICA-BAA-E2.1.8 and firmware version mfw_nrf9160_1.2.8. 
 Also I'm using nRF connect sdk with version 1.5.1. 
 
 Currently I can compile my application and run it on nRF9160 DK and use %CESQ to check if device enters PSM. 
 Device's T3324 is set to 2 minute and T3412 is set to 5 minutes. 
 The odd behaviors I find are the device can still be interact after entering PSM and it seems not detached to network (by using AT+CGATT to check). 
 Other modem I tested with this SIM card like BG96 and R410m does not act like this when they enter PSM. 
 So my question is does these odd behaviors indicates that device didn't enter PSM? 
 
 Here are some simple logs: 
 > AT%XMONITOR
%XMONITOR: 1,"","","46697","5829",9,28,"04943366",,,,,"","00100010","10100101","01011111"
OK
> AT+CPSMS?
+CPSMS: 1,,,"10100101","00100010"
OK
> AT+CEREG?
+CEREG: 5,1,"5829","04943366",9,,,"00100010","10100101"
OK 
 
 Also I have tested the power consumption by using HVPM through the usb port. 
 The results shows the device acts really like PSM after T3324 timer expired.

Any suggestions will be helpful !

Didrik Rokhaug · Accepted Answer

Hi, 
 When in PSM, the device is still registered to the network. So it is expected that the modem reports that it still is connected. 
 One way for the application to know that the modem has entered PSM is to use the %XMODEMSLEEP or %XT3412 commands to get notifications when the modem goes to sleep. 
 However, while the modem is sleeping, it can still be woken up to reply to AT commands or to send data before the PSM interval is over. 
 Some modem manufactureres does not keep the necessary contexts while in PSM, in order to get a lower idle power consumption. However, this means that they have to do a full network re-attach when waking up, which in most cases ends up consuming more power than they saved while in idle. As they are not able to maintain their connection after waking up from PSM, it would make sense that they report that they are not connected while in PSM. 
 Best regards, 
 Didrik

nRF9160 dk can still be interact and not detached to network while in PSM

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