NRF9160 RRC Connection Re-established CMW500

[bsams]

We're using the CMW500 to talk to the NRF9160, and it connects ok but then gives the message "RRC Connection Reestablished". We tried using the asset-tracker example, which works fine with a normal sim connecting to AT&T, but has this issue with the callbox. We followed the instructions in this post, which helped resolve a previous problem (signalling error), but didn't resolve this issue. Interestingly, the UDP example seems to work ok, maybe because it doesn't stay connected long enough for this to happen (it gives the "RRC Connection Reestablished" message ever 1 second).

 

[Didrik Rokhaug]

Hi,

I have talked to one of my colleagues with experience with a CMW500, and he agrees that this is not normal. However, he is not able to say what is configured wrong.

I have asked our modem team for their help, as they have more experience with the CMW500 than we have. I will let you know when I hear back from them.

Best regards,

Didrik

[Didrik Rokhaug]

Hi,

Please see the answer I got from the modem team:

If asset tracker is used it could be that data transfer is started and CMW500 is configured for test mode.
The dfl files included in the blog are also using test mode as these are for signalling testing purposes.
I attached a new dfl file where test mode is replaced by data application (requires CMW HW option B450) as connection type so any data will be now be sent to CMW500 without test mode configuration.
If they want to include asset tracker in their testing, can they try attached dfl file if it helps (for the data to be sent to "internet" CMW500 DAU needs to be configured to match testing setup, attached dfl file contains data to be sent to CMW500 only).

If this dfl file doesn't help for RRC connection re-establishment issue, can they take modem traces?

Attached dfl file is created for callbox 3.8 versions so if they have older callbox version(3.7.x) then we might need to make a new one for 3.7.x.

M1dataCMW500.zip

Does the attached configuration work?

If not, could you take a modem trace?

Note that if you are using NCS v1.5.0, you must add CONFIG_NRF_MODEM_LIB_TRACE_ENABLED=y to your prj.conf file instead of CONFIG_BSD_LIBRARY_TRACE_ENABLED=y.

[bsams]

Hey Didrik, this file seems to stop the rrc reconfiguration issue, but can you elaborate more on what needs to be done to allow the DUT to connect to the internet with this config? (I'm also not completely sure that this has solved the issue, because it seemed like the rrc reconfiguration may have had something to do with internet connectivity)

[Didrik Rokhaug]

This is what the modem team answered:

They need to connect ethernet cable from external network to CMW500 Data application unit (DAU) connector on the backside of CMW500.

See also attached picture how to configure DAU (IPV4 only configured here) from Data application measurements.
By doing this, all data from / to nRF9160 will go via CMW500 DAU to external network (like internet).

We can send them new dfl file for internet connection but we should know first which callbox SW version they are using as different versions can crash callbox SW.

R&S DAU user manual (mainly chapters 3.1 and 3.2) have also information how to connect, this document can also be found from R&S Gloris website.

Some of the above information can also be found from the blog as below : https://devzone.nordicsemi.com/nordic/cellular-iot-guides/b/hardware-design/posts/using-nrf9160-against-r-s-cmw500-or-cmw290-in-signalling-callbox-mode
#To enable internet connection, select Data Application in GUI config of Connection type. This testing requires HW option B450I (DAU unit) and SW options like KA100/KA150 and KM050/KM051/KM052 might be required
depending on the testing need.
This can also be bought as a bundle (PK45)."