Occasional failing of ^SWWAN on PLS8-E | Telit Cinterion IoT Developer Community
October 14, 2022 - 3:12pm, 149 views
we us a PLS8-E (or PLS8-US, region dependent) in our small data loggers for data upload. For every upload-session we power on the modem, configure, upload and shut down. We do this some years without problems.
Then we wanted to get rid of the pppd overhead and switched to using the AT^SWWAN functionality.
In 95% the procedure works, but occasionally the AT^SWWAN=1 fails:
AT+CEMODE? // We make sure, the device is datacentric
AT+COPS=2 // deregister from the network to allow PDP 1 to be changed
AT+COPS=0 // register again
AT^SGAUTH=1,0 // no user/pass for this APN/provider required
AT^SWWAN=1,1,1 // activate USB network interface
+CME ERROR: unspecified GPRS error
In this situation, a delay and repeat of the last command also fails.
Without changing anything I then continue with ATD*99***1# to build the PPP connection with pppd. This always works, so PDP 1 is ok, the modem can connect to the network etc. Why did SWWAN fail?
What might be the reason for the occasional "+CME ERROR: unspecified GPRS error"?
With the next power off/power on, the SWWAN works perfectly again. Same network, same SIM, only minutes later.
The command sequence is trimmed to fit as many different SIM cards as possible, which may differ in PDP usage etc.
Is there a state which I should check before issuing the AT^SWWAN=1,1,1?
The error description unfortunately does not specify any particular cause. You can try to add some more debug information to your application, like enabling additional URC's related to packet domain like AT+CGEREP=2 and errors with AT^SIND="ceer",1. Additionally you can monitor the network parameters by sending AT^SMONI periodically or when you set up the connection. Check also AT+CGATT?, AT+CGACT?, AT+CGCONTRDP.