Mod

@techno819 did you try the 43 page guide linked from https://www.mysensors.org/controller/openluup ?

@mrhutchinsonmn a single rs485 connection can use the MySensors protocol, just as a single nrf24 can.

Welcome ro the forum @Highland

MySensors supports two rfm69 drivers; the ”new” and the ”old”. They are not compatible.

So anyone with an existing rfm69 MySensors network probably wants the old driver, which is default.

Anyone startung to build a new network should use the new driver by adding the define to all sketches.

The nrf24 radios are lowest cost, about 13 usd for 10 modules. They also have shortest range (10 to 50m depending on a lot of factors) and largest risk of interference from other devices since it uses the same frequencies as wifi and bluetooth. No need to solder, you can use dupont wires directly or a socket.

The rfm69 radios are the middle ground. About 15 usd for 10 modules. Can be bought for different frequency bands (433MHz, 868MHz, 915MHz). Different regions in the world allow different frequencies, so you'll have to share where you are or find what the law says for your area. Range is approximately 20m to 100m. These are generally harder to solder since they don't use 2.5mm. Using easypcb can be a simple solution.

LoRa radios can also be bought for different frequencies. They cost about 37 usd for 10 modules. If you pay the extra royalty to Semtech for LoRa, do not use FSK. If you plan to use FSK, go with rfm69. Range can be up to several km in the right conditions, but it will depend a lot on the local radio environment. rfm95 and rfm98 are examples of LoRa radios.

A 9V battery is not a good choice. The regulator on the arduino will burn off 2/3 av the available power, so you'll have a physically big battery with very little practical capacity. Look at https://www.mysensors.org/build/battery instead.

@willemx the documentation is correct. The gateway is not necessarily the next stop. But since you don't have any repeaters, and the node is sending to the gateway, the gateway will be the next stop.

send() returns true if the the sending node received an acknowledgement from the next node. The nodes automatically resend unil they receive the acknowledgement (or a limit is reached), so there is absolutely no guarantee that the message was sent only once.

If you want to read up on the information theory, check Two Generals' Problem especially this part:

The Two Generals' Problem was the first computer communication problem to be proved to be unsolvable.

@willemx the gateway most likely sends acknowledgement for every message. But the node might not hear every acknowledgement, and will therefore resend.

It is impossible for the gateway to differentiate between a resent message and a new message with the same content, so the gateway dutifully forwards both messages to mqtt. The mqtt broker is in the same situation as the gateway: if it gets two messages, it forwards two messages.

The only reliable way to distinguish between original messages and resent messages is to use something similar to a sequence number. MySensors does not use such a thing.

@willemx depending on the QoS value of an MQTT publish the same message can arrive multiple times at subscribers. This could be the issue.

@willemx the gateway debug log should show what is happening.

nice work @Oumuamua, thanks for reporting back.

@Rez sorry, that sketch is way too complex for me to understand.