MC7455 takes several retries to attach to network on power up

IoT Modules MC/EM Series
1

Hi All,

We are trying to use MC7455 in one our product. It kind of works but we have some issues as mentioned below.

  1. MC7455 attaches to network on soft reboot of our product. That is typing reboot at command prompt in linux.
  2. MC7455 does not attaches to network on power up immediately. It takes several reties (I have to reset modem 3/4 times) for modem to attach to network.

I use following sequence to attach to network

GetCurrentProfile
If(currentProfileApn != ApnToBeConfigured)
{
deleteProfile
ConfigureUserProvidedProfile
}
ConfigureIPFamilyPreferance
StartDataSession
MonitorConnectivity

Not sure what I am missing here. FYI - I am using lite qmi sdk and gobi driver. Let me know if you have any suggestion or pointer for this kind of problem.

@anon56110884 do you have any pointers on this.

–
Thank You!!!

2

Hi @Dhruval,

Your problem is not with attach. When the modem boots up it will attach to the NTWK and on LTE, it will acquire an IP address. You don’t need any QMI or AT cmds to attach to the NTWK.

With QMI you are bringing up the session between the modem and the host.

So before calling StartDataSession your modem must be attached to the NTWK and must have an IP. (except on Verizon where the default attach and default data profiles are not the same)

Your logic is OK.

Maybe for some reason the attach procedure failed or the modem is still searching when you try to bringup StartDataSession.

I’d suggest to check the IP address or attach state before you call startdatasession.

To troubleshoot the issue use AT!GSTATUS? , AT+CGCONTRDP

Thanks,

James

3

Thank you @Oedenburger,

Locking the RAT(AT!SELRAT=06) to LTE solved the problem. Before it was set to auto(AT!SELRAT=0).