EXS62-W loses connection after a few minutes | Telit Cinterion IoT Developer Community
October 30, 2021 - 3:58am, 1071 views
Good evening, I hope you can help.
I am working using the EXS62-W at the moment, and seem to be struggling with keeping connectivity
- Connection to the internet is lost after approx 1 minute of standby
APN is configured, Hologram is my provider.
+CGDCONT?
+CGDCONT: 1,"IP","hologram","0.0.0.0",0,0
+CGDCONT: 2,"IPV4V6","attm2mglobal","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0
+CGDCONT: 3,"IPV4V6","m2m.com.attz","0.0.0.0.0.0.0.0.0.0.0.0.0.0.0.0",0,0
OK
I can connect to the internet just fine using AT^SICA=1,1, and a ping to Google succeed by both IP and name. My dashboard on Hologram also shows an active data session and data consumption.
+CFUN=1,1
OK
^SYSSTART
^SICA=1,1
OK
^SISX=Ping,1,"8.8.8.8",5,1000
^SISX: "Ping",1,1,"8.8.8.8",350
^SISX: "Ping",1,1,"8.8.8.8",228
^SISX: "Ping",1,1,"8.8.8.8",228
^SISX: "Ping",1,1,"8.8.8.8",157
^SISX: "Ping",1,1,"8.8.8.8",157
^SISX: "Ping",2,1,5,5,0,0
^SISX: "Ping",3,1,157,350,224
OK
^SISX=HostByName,1,"www.google.com"
^SISX: "HostByName","74.125.206.106"
OK
However, if I leave the device alone for even ~60seconds, the same ping will fail, returning -1.
OK
^SISX=Ping,1,"8.8.8.8",5,1000
^SISX: "Ping",1,1,"8.8.8.8",-1
^SISX: "Ping",1,1,"8.8.8.8",-1
^SISX: "Ping",1,1,"8.8.8.8",-1
^SISX: "Ping",1,1,"8.8.8.8",-1
^SISX: "Ping",1,1,"8.8.8.8",-1
^SISX: "Ping",2,1,5,0,5,100
OK
If I'm reading the datasheet correctly, signal strength is good.
+CSQ
+CSQ: 31,99
OK
So, I'm struggling to understand what is causing my session to be disconnected? To further support this - I can successfully open an MQTT session, and publishing data to the broker from a Windows client, each time I do this - I can receive the data on the wireless device, until approx 1 minute later the session is disconnected again - so even if I'm trying to keep the session 'open' by keeping data flowing, I still get disconnected.
So at the moment, I'm unsure if this is a network or wireless module issue.
Many thanks in advance!
EDIT - as further information, it seems I an unable to reestablish a connection after this 'timeout' - and until either a power cycle or software reset, I cannot ping anything, as per below.
+CFUN=1,1
OK
^SYSSTART
^SICA=1,1
OK
^SISX=Ping,1,"74.125.39.99",3,3000
^SISX: "Ping",1,1,"74.125.39.99",407
^SISX: "Ping",1,1,"74.125.39.99",275
^SISX: "Ping",1,1,"74.125.39.99",507
^SISX: "Ping",2,1,3,3,0,0
^SISX: "Ping",3,1,275,507,396
OK
^SISX=Ping,1,"74.125.39.99",3,3000
^SISX: "Ping",1,1,"74.125.39.99",399
^SISX: "Ping",1,1,"74.125.39.99",180
^SISX: "Ping",1,1,"74.125.39.99",241
^SISX: "Ping",2,1,3,3,0,0
^SISX: "Ping",3,1,180,399,273
OK
^SISX=Ping,1,"74.125.39.99",3,3000
^SISX: "Ping",1,1,"74.125.39.99",-1
^SISX: "Ping",1,1,"74.125.39.99",-1
^SISX: "Ping",1,1,"74.125.39.99",-1
^SISX: "Ping",2,1,3,0,3,100
OK
^SICA=0,1
OK
^SICA=1,1
OK
^SISX=Ping,1,"74.125.39.99",3,3000
^SISX: "Ping",1,1,"74.125.39.99",-1
^SISX: "Ping",1,1,"74.125.39.99",-1
^SISX: "Ping",1,1,"74.125.39.99",-1
^SISX: "Ping",2,1,3,0,3,100
OK
Hello,
Do you have any other SIM (from other provider) to compare?
What RAT is it - please check AT^SMONI output. CSQ is only applicable to 2G.
What is AT^SICA? output when this happens?
Is the module still registerd to the network when this happens (AT+COPS?)?
SICA=1,1 seems to succeed. Please check AT+CGPADDR output.
Please try to activete some URCs like
AT+CREG=2, AT+CEREG=2, AT+CGREG=2, AT^SIND="ceer",1, AT^SIND="service",1, AT^SIND="psinfo",1, AT^SIND="prov",1
BR,
Bartłomiej
Hi,
Thanks very much for getting back to me. I don't have access to another provider, but have tried multiple SIM cards from the same provider - all show the same behavior. That said, we managed to get the connection stable and the next morning saw your post regarding RAT, so it was good to see we were on the right track.
We've been setting the RAT to LTE-M only mode using AT^SXRAT=7, and that single change resulted in a successful 24 hour connection test sending a ping once every 5 minutes. This leads me to think the module is attempting to switch between NB-IoT and LTE-M connections when set to the dual access RAT mode. Setting the RAT to 8 (NB-IoT) however, I am not able to establish a connection at all.
This makes me think this is more an issue with the provider. We are using Hologram, which connects us to the O2 network in the UK. O2 don't appear to provide NB-IoT in the UK yet (but rather, Vodafone do) - although there is limited material on their site that suggests they do provide NB-IoT. I am waiting on confirmation from the provider on this at the moment.
I don't have access to the hardware tonight to check the output of the various URCs you suggest. I will do this tomorrow night and report back, on both RAT modes 7, 8 & 10 - though I assume in the case of RAT mode 10, the URCs are going to contain information that suggests a switch between the two RATs causing a disconnect?
I have seen a separate issue, 2 or 3 occurrences in the last few days, which I need to try and reproduce - where the module seems to become totally unresponsive, and simply sends out NULL bytes over the serial port every 5-10seconds continuously - and will not respond to any commands, including software resets. The only thing I can do to recover from this is to perform a power cycle.
Many thanks for your help, I look forward to getting these 2 issues worked out fully to allow us to build more confidence in embedding the module into our application. This new issue with the module going unresponsive has been particularly concerning, as it is pushing us towards wanting to implement power switching to the module to allow us to perform a power cycle commanded by the system's microcontroller.
Hello,
I think this problem ***** more debug to see what really happens.
Anyway it's good that it works with AT^SXRAT=7. Maybe NB-IoT is not supported or is only in some areas.
URCs should show the network registration statuses and changes and possibly also errors.
The second issue suggests some HW problem with the module, maybe related to power supply, and it ***** an investigation. You should first make sure that your HW was designed in accordance with our HW spec for the module.
BR,
Bartłomiej