Unsolicited “NO CARRIER”

10 thoughts on “Unsolicited “NO CARRIER”

  1. GE864 QUAD V2 sw 10.00.022

     

    I’m receiving “NO CARRIER” like UCR i.e. it is not reply to a AT command send before.

     

    What I should do in that case? Is there a way to configure its behavior?

     

    Ignoring that message seems to work well, but I’m afraid that in this way can ignore important replies.

     

    You can found one whole session into the attached log file.

    1. The latest firmware is 10.00.xx8, please upgrade and test again. This proble was discussed several times, see for example " Receiving URCs during AT command execution" thread #1447 and "How to handle URC and command echo correctly?" thread #1259.

  2. Upgrading the firmware helps to reduce this "NO CARRIER" URC, but it still appear from time to time. I’m adding a log file to see the details.

     

    Note that log file is manualy edited from my logic analyzer export on linux desktop – i.e. line endings are changed, in the original they were:

    – r for all AT commands send to the modem

    – rn for all modem replies as well

    and may be there are some other mistakes, if it will help, can attach saleae analyzer file instead.

    1. The NO CARRIER is received when the socket is closed. I assume that in this case the socket is closed by the remote host.

      When the socket is closed (i.e. NO CARRIER) you can verify immediately the status with AT#SS=1, verify that PDP context is still active with AT#SGACT?

      If the response is #SGACT: 1,1 then un can simply open the socket again with:

       

      AT#SD=1,0,3706,trackbox.ubidata.be,0,0,1

       

      It is not necessary to deactivate the PDP context with AT#SGACT=1,0 and resend all the configuration again.

       

      some other suggestions:
      AT&K=3 syntax is wrong, the correct syntax is AT&K3

  3. Thanks, it makes sense now.

     

    Is it possible to control SRING and NO CARRIER URC’s?

     

    It makes AT commands reply parsing more complex that it is necessary and will be perfect if we can disable all URC’s.

  4. I think not maybe because they are essential for asynchrounous operations where the assumption is that all notification are processed by the logic parser.

    1. Can you please confirm that this is really not possible?

       

      Our usage is strictly synchronous:

       – we are sending one AT command at the time and waiting for its reply (OK/errors)
       – we are using just one serial line to communicate with the modem

       – we are always in command mode – our communication is based on the build in the modem TCP/IP stack and we are not switching between data and command mode at all.

       

      Handling URCs in our case really complicates our software and creates possibilities to miss important errors in some cases. If there is a way to disable all URCs we can handle it in a much better and stable way. For the moment the only one that we were not able ti disable and are still observed are these two – SRING, NO CARRIER.

       

      May be it will be helpfull if you have client side library that we can reuse where all URCs and AT commands are handled in a good way – we don’t have visibility what happen in the modem to do that ourselves with a good quality and maintanability.

      1.  

        Is it possible to control SRING and NO CARRIER URC’s?

         

        It makes AT commands reply parsing more complex that it is necessary and will be perfect if we can disable all URC’s.

         

        No. these URC’s are mandatory as defined in the 3GPP standard.