Double or missing packets
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I’m building an IoT device that sends data to my server every 30 minutes. For this, I use a BK7020 on the T-Mobile network. The problem is, very often a lot of packets in a row don’t ever arrive at our server.
Then, sometimes a packet arrive two times, despite the function that sends data really only being called once. I have tried this with multiple BK7020’s, all have the same problem. The BK7020 doesn’t give me any error codes, and just returns an OK. I have added capacitors according to the BK7020’s documentation.So, I am 100% sure I’m only telling my SIM Modem thing (the BK7020) to send the packet once. I am also 100% sure the packet sometimes arrives twice, with like one or two minutes inbetween. Could this be an error on the side of T-mobile? Or is it more likely internal fuckery of my BK-7020?
I should probably look into this myself, so would setting up AllThingsTalk be a productive way to help debug this? If not, do you have any other suggestions? The API is still opaque wizardry to me, but I’m willing to invest a couple of days to figure it out if that would help.
With kind regards,
Vincent
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@Sopwafel Hi, please make sure you are running the latest FW. Have you tried with a different modem? The SIMCOM 7020 is quite old…
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@Stefan-de-Lange Thanks for the suggestion! Both things I hadn’t considered yet. Will be looking into them.
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@IoT-Arista and @Sopwafel,
If you still encounter problems, I can try to investigate for you in the platform whether the subscriptions to your data contain any errors.
You can send me a direct message or a mail to our mailbox with the device and account details.
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@Stefan-de-Lange Do you have suggestions for an alternative?
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@IoT-Arista I really like Nordic nRF9160!
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@Stefan-de-Lange Thanks for the suggestion! We already have most of our development done with our own PCB using an ESP32 and SIM7020E. What I can gather about the nRF9160 is that we can either use a full DK or the SiP. Both seem prohibitive, as it would be wayyyy more work than just switching out the SIM breakout and changing AT commands and routines and such.
Am I correct in thinking this? I’d very much love to have (more) reliable data transfer, but also don’t have the time to do a large overhaul.
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@IoT-Arista Interesting combination. You are right, nRF9160 requires a very different development strategy. It uses Zephyr RTOS and c-api’s to control the cellular modem. In my opinion it is much better to work with than the ancient, slow, outdated AT interface. But if you want to use AT commands on nRF9160 you still can:
https://github.com/nrfconnect/sdk-nrf/tree/master/applications/serial_lte_modemIf you don’t want to redesign you should contact SIMCOM and t-mobile ( @Eric-Barten ) to fix your issue