Serial LTE Modem - Unable to send or receive TCP/UDP packets

[Mark H]

I'm testing the Serial LTE Modem application on the nRF9160DK with the LTE Link Monitor. I want to use the DK as a UDP client to send data

to my remote server via UDP over LTE. I can communicate just fine between my PC and server and I can ping the server from the nRF9160DK.

I've been following the documentation for the Serial LTE Modem but I'm unable to actually send or receive any UDP (nor TCP) packets from the nRF9160DK

as seen in the logs below. I just get errors but no more information.

2021-07-20T12:49:54.450Z DEBUG modem >> AT#XSOCKET=1,2,0
2021-07-20T12:49:54.476Z DEBUG modem << #XSOCKET: 1,2,0,17
2021-07-20T12:49:54.479Z DEBUG modem << OK
2021-07-20T12:49:59.501Z DEBUG modem >> AT#XCONNECT="***.***.***.***",1234
2021-07-20T12:49:59.531Z DEBUG modem << #XCONNECT: 1
2021-07-20T12:49:59.537Z DEBUG modem << OK
2021-07-20T12:50:04.818Z DEBUG modem >> AT#XSEND="Test"
2021-07-20T12:50:04.842Z DEBUG modem << ERROR
2021-07-20T12:50:04.845Z ERROR Error: AT#XSEND="Test" failed
2021-07-20T12:50:16.906Z DEBUG modem << %CESQ: 59,2,22,3 

 I'm using the included iBasis eSIM and I have tested the asset tracker and it worked fine with the latest firmware updated (as of this post) and v1.6.0 of the nRF applications.

I'm not sure how to proceed from here and if it is possible to get more information from the logs.

Thank you.

[Albrecht Markus Schellenberger]

Hello Mark,

My apologies, but the documentation is not optimal here.

Could you please try this one instead:

2021-07-21T09:17:07.017Z DEBUG modem >> AT#XSEND=1,"Test"
2021-07-21T09:17:07.032Z DEBUG modem << #XSEND: 4
2021-07-21T09:17:07.033Z DEBUG modem << OK

As an alternative for UDP I would recommend you use #XSENDTO or #XUDPSEND.

I hope this will help you!

Regards,

Markus

[Mark H]

Thank you I missed that but it solved my problem!