MC74xx Modem Double Attach


#1

Using Linux SDK for PDN connection, and I had network registration preference (netReg) set to “Automatic registration”. When I perform PDN connection, the test equipment receives 2 attach messages even though there is only 1 PDN successful connection (i.e. no drop of connection then reconnect). Unfortunately the test set doen’t capture RRC messages to see the details of what’s going on, and I’m a little confused why there are 2 attach requests with what looked like to be the same registration information. Anybody has an idea why?


#2

Hi,

Are you using the Sierra Wireless SDK or the open source one, if the Sierra one what API are you using and paramter?

Regards

Matt


#3

I use Sierra SDK SLQSStartStopDataSession to start the data session, and with network attach preference set to automatic. The connection is clean from SDK perspective, no errors, no disconnect/reconnect, but the test equipment displays 2 attaches every time for the one connection. It’s not doing any harm, just unexpected signaling behavior causing some confusion.


#4

If you take a log file from the unit we can see what is going on with the unit from its side?

The logging port on the MC is /dev/ttyUSB0, you can take a log file using the dmcapture script which is contained in the SDK zip file under /tools/logging/dmcapture, there is a help file in the showing you how to take a log file

Regards

Matt