Ensuring reliable cell connection and retrying?


Hey Francis - we updated our heartbeat and that appeared to have solved our problem! I believe that since we had not set the heartbeat the MangOH was sending ‘register update’ every second since it didn’t have a default set. We changed our heartbeat to 20 minutes and now we have had systems online for almost 4 days.

Thanks very much!



Good news if the heartbeat solve your problem.
For information 2 thing are missing in legato source on github:

atAirvantage and atQmiLinker are missing and this app are not included into the final build.

This app are in charge of at command for AirVantage (AT+WDSC AT+WDSI). Included the AT command to set the heartbeat.

If some people are interested I have a cwe binary for legato 17.11 included this 2 app (for wp85)


Looks like we are still having some issues here. The heartbeat seemed to have helped us, but all of our units (4 of them at different times in 24 hrs) have begun going offline again. The units seem to be stuck in some infinite loop of trying to register to the network after every heartbeat. @dclark75 @dfrey - should I consider eliminating whatever service does this? Or am I stuck with having a timer that reboots the unit every 6 hours for safety’s sake - we have our first proof of concept deployment on Friday.



I am going to test with this on some more and see why you are seeing communication stop - If you have any logs (from using logread -f) feel free to pass those along. For now you can go in AV and select the Configure communication and turn off the heartbeat for now. With this setting off i was having no problems for weeks around xmas with AV communication. I will let u know here when/if i find any bugs with AV communication with the heartbeat enabled.


Thanks @dclark75.

We have run into another problem with our connection to AV, which may be related to the heartbeat… We get Registration Expired, which kills our units (also makes it impossible to do remote reboots).


We have added a ‘kicker’ app that reboots the hardware every 6hrs now so that we can avoid these kind of hiccups.



Do you try to integrate a avcController into your app ?

I use 2 applications :

1 . A avcController who manage airvantage connection (start session OTA update reboot etc…) who provide API.

  1. A push application who read data from device and push it to airvantage.

I use IPC binding to read connection status from app 2 to app1.

You have a example of acvControl and IPC into app sample (avcControl and HelloIPC) in legato.

My avcController manage sim disconnection too.

You can use your avcController for all application. Just expose the api (IPC = Inter Process Communication)

This my spirit for Airvantage application.



Hey @dclark75, i’m not sure if turning off the heartbeat is going to help us. We just lost our session with airvantage again on one of our units (without the heartbeat) - this means that we can’t push a remote reboot to the unit, which in the past we could because the heartbeat would retrieve that command when it made its own connection.

Just as a reminder - we are basically just using the RedSensorToCloud timer loop in our code with the existing session handler code.



Do you have a developper contact with Sierra WIreless ?
You can ask support to investigate your problem.



Hey I am testing now to try and see if I can re-create your problem with AV communication hanging - I have the heartbeat enabled for every 15 minutes. For the registration expired i am going to ask as i am not sure what that means - dave


Unfortunately we are still going through the process of becoming a Sierra partner, so we don’t have any specific contacts.


Did you try to implement wake up by sms ?
I have it in my avcController.

You add en sms rx handler message. When you receive WAKEUP text message you stop/start a avc session.


We haven’t tried that yet, thanks for the suggestion :slight_smile:


@coastalbrandon were you able to recreate with logread running? I did manage to see the pushes to AV stopping but I was using WiFi and correct me if i am wrong but you are using cellular correct? I am going to put in a fix for the stopping due to a WiFi disconnect


Hey @dclark75, we haven’t had a unit lose its connection and allow us to connect with a USB cable. When we plugin to the unit and ping it never responds, this seems to happen after some unknown period of time with all units (even when they’re still communicating to AV). We have to power cycle them to have the USB work again, which loses our logs.


connect the second usb (serial consol). You will be able to open a console session and start a logread-f and make a screen copy of the result.

If you’re lost the air vantage connection and continue to push data , legato have a bug (memory used to push is not released ) and the app finish to crash. This pb will be fixed in 18.01 (information from legato team).

A avcController is a good solution in this case.


@coastalbrandon in this scenario are you able to use the console with TeraTerm in these situations? Is the device resetting after communicating with AV ( I have seen this one and working thru these bugs still) - if you are able to see this again could you put the output of the logread command here (assuming of course you can console in) - thnx @dclark75