Message "#SL: ABORTED" and Spacebridge


#1

Hi everyone,

I’m having trouble with spacebridge and connecting over time to an IoT device. Here is the configuration:

  1. Multitech Dragonfly modem with Hologram SIM
  2. Sets up and connects to the network fine. The Multitech uses the Telit HE910 chipset which works great.
  3. Set the modem to listen mode with “AT#SL=1,1,2222” to tell it to enable a TCP socket listen on port 2222.
  4. Run spacebridge setup to map the modem to a local port.
  5. Connect to the modem. Works great!
  6. Disconnect from the modem and get “NO CARRIER” as I should.
  7. Resend the listen command - “AT#SL=1,1,2222”.

Here is where I have a problem. If I don’t connect to the modem again through spacebridge within about 45 minutes, I will get this message from the modem:

#SL: ABORTED

I cannot figure out why, although I would assume some kind of timeout issue. According to the documentation this means the network kicked me off for some reason. If I then reinitialize the socket on the modem and set it back to listen mode the modem seems like it works, but I cannot reconnect to the modem again through spacebridge until I close the spacebridge app and re-run it. This is on a Win7 machine.

I get these odd messages in spacebridge about “remote device has closed the connection” and I will keep getting them until I run it again. I suspect this has something to do with key generation, but since I don’t know why I got kicked off or how to prevent it, I’m kind of stuck.

This problem seems to be unique to hologram. The exact same configuration with a Verizon SIM does not exhibit this behavior, although in that case I had a fixed IP address for the modem. But it never kicked me off the network no matter how long I waited to make the connection.

Questions:

  1. Why do I get the “#SL: ABORTED” after 45 or so minutes of not linking to the modem?
  2. How can I prevent the “#SL: ABORTED” from being sent? Is there some kind of periodic activity I need to initiate on the modem to keep the link active while I wait for an incoming connection?
  3. Why does spacebridge need to be shut down and restarted to fix the problem?

Thank you in advance for any help you can give.

  • Rebecca Taylor
    Sr. Engineer, Diamond Edge Technology, LLC

#2

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