Max Message Rate and Stress Response Questions

  • Has anyone done some testing to see what the maximum overall message rate the library/hardware can support? Or what happens when that rate is exceeded?

    Failing that, does anyone have an idea of a ballpark figure or rule of thumb to keep the system stable?

    How does MySensors deal with messages clashing? Is there a way to guarantee certain messages will get through? Or assign a higher priority to some? Or is it up to the sketch author to send messages with the acknowledge flag set and then manually process ack receipts/retry on fails?

    For reference my system is based on Arduino/RFM69-433/MQTT.

  • Mod

    The different transports allow for different collision handling, since the transports are inherently different. So there is no way to answer his question generically.

    AWI stress tested rs485, see

    For nrf24, it would probably depend a lot on the quality of the radio chip (see ) and the power supply. The collective experience is that the nrf clones are extremely sensitive to noise on the power supply, which would affect the chance of getting a message through.

    The length of the message also makes a big difference, which we have seen bite signed messages since they always use the maximum message size. I don't think the rfm modules have this problem.

    The network topolgy would probably have a big effect, since a repeter essentially cuts the available bandwidth in half.

    See also for a discussion on a similar topic.

    I haven't seen anyone posting results from a rfm stress test. Please share the results if you do any stress tests for your particular setup. It would be interesting to see.

  • Thanks, I will look at doing some stress testing I think. I'm starting to see the occasional missed message already and I'm only averaging 1 message per 3 seconds.

    Does anyone know how the RFM modules handle collision/retransmission?

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