Tasmota: Control one device with another

[mizrachiran]

Hi Guys,

I would like to know if it's possible to control 1 Tasmota device with another.
(will be used to control living room lights from 2 different locations in the house).

What i had in mind is that 1 device will be connected and will 'really' control the light. the other will only have switches defined.

While I can set the state topic to be the same, it doesn't seem right as the topic used to report LWT and state.

Is such scenario already supported by Tasmota?
Any suggestions?

Thanks!!!

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[wongnam]

Try use SwitchTopic https://github.com/arendst/Sonoff-Tasmota/wiki/Understanding-SwitchMode-and-SwitchTopic

• default Switch1 press it will send a default or custom topic(depending to your config) via MQTT with default postfix is POWER1 (ed: cmnd/2nd_sonoff/POWER1, Switch2 if pressed it will send command via MQTT with default postfix is POWER2
• i just wonder to know if any way to use Switch1 from the 1st_sonoff to remote the 2nd_sonoff Relay2

[wongnam]

ok i found rule can fix my issue : use Switch1 from the 1st_sonoff to remote the 2nd_sonoff Relay2

[mizrachiran]

Thank you @wongnam.
I looked at the documentation, SwitchTopic looks promising so far...

One question, it is possible to control one device with another using SwitchTopic 2. in such case it will have to know the state of the relay in the other device in order to send the right payload - ONOFF.
How does it work?

Thanks,
Ran

[wongnam]

in this case I recommend use Rules for more powerful and flexible.

https://github.com/arendst/Sonoff-Tasmota/wiki/Rules

note: Disable ButtonTopic as it overrides rules for buttons: ButtonTopic 0

[mizrachiran]

It could work if we could send Toggle on switch action.

[wongnam]

Look at switchmode

[wongnam]

SwitchMode 3

[mizrachiran]

Using SwitchMode 3, will it send toggle command?

[wongnam]

Yes. Send “TOGGLE”

In case of using onboard Button use ButtonTopic

[mizrachiran]

@wongnam thank you so much for the assistance.
I will test it today and update this case accordingly.

Ran

[wongnam]

Eg: type in console.
Case 1: sonoff1 connect an external button on GPIO14 + GND to remote a sonoff2

• SwitchTopic sonoff2
• SwitchMode 3

Case2: use an onboard button on sonoff1 to remote sonoff2

• ButtonTopic sonoff2

[wongnam]

@mizrachiran Try knx feature, it's more than what you expect

https://github.com/arendst/Sonoff-Tasmota/wiki/KNX-Features

Especially it does not need to use mqtt broker

[mizrachiran]

I just tried the SwitchTopic, it seems to be working.
The only thing that i don't understand is why the mqtt topic that sent from this device is not addressed to specific relay.
it sends "cmnd/MySwitchTopic/POWER" while I was expecting POWER1, as I set this GPIO to Switch1.
Is that intentional?

[ascillato]

In Tasmota, POWER means POWER1. If you want Tamota to explicit POWER1 use on the console: setoption26 1

Please, see commands in the wiki (https://github.com/arendst/Sonoff-Tasmota/wiki/Commands)

[mizrachiran]

That make sense.
But why when I set this GPIO to Switch2 Switch3 it still sends the same command (POWER)?

[mizrachiran]

I solved it by defining non existing Relays in the module config.
when only switches were defined, it's always send POWER1.

@wongnam, @ascillato, Should I open bug for that or is it by design?

[wongnam]

i think it is feature limited if you use ButtonTopic to send command to the same device or another device relay 2, relay 3..

• Try to use rule, Rule can publish a command like cmnd/sonoff/POWER3
  try this. Rule on Button2#State do Publish cmnd/sonoff/POWER3 %Value% endon
  note: Disable ButtonTopic as it overrides rules for buttons: ButtonTopic 0
• KNX also very easy to remote another device by button.

[wongnam]

if you defined Switch2 Switch3 then change the word "Button" to "Switch" in the rule.

[mizrachiran]

@wongnam thanks for the suggestions.
I know i can achieve the same with rules knx.
However, this basic scenario would be much easier to maintain and setup with just setting state topic and configuration of GPIOs. and it seems to be working great.

I still think there is a bug here we should look into:
If my module configuration has only switches defined as follow:
GPIO4 -> Switch1
GPIO5 -> Switch2
Why Tasmota is sending Power1 on both switches action?
When I also map relays it works as expected...

[maxen0815]

Hi guys,
I'm reading this topic since I'm interested in this function, too. Can you tell me if there also is a solution which is able to run without MQTT broker in between?
The idea is to have one tasmota controlled button directly sending an HTTP request within the same network to trigger another tasmota device like power switch. Could call is Wifi remote control...

BR maxen

[mizrachiran]

@maxen0815, this scenario is possible using KNX Rules.

[wongnam]

@Ran because of limited issue so Tasmota implement rules.
See this article “A problem with this solution is that on a Sonoff 4CH all four buttons will be sending the same MQTT topic using only a different Power index number like cmnd/buttontopic/power3 toggle.

By using a rule a single button can now send any MQTT message allowing much more flexibility.” that I capture it from wiki.

@maxen0815 Go with KNX, yep no need MQTT broker.

[mizrachiran]

This is actually what I want, that every switch button will send the same topic with different index.
What's happening is that all of the buttons trigger the same command...

[maxen0815]

Thanks for these quick responses! I'll give KNX a try.

[wongnam]

Because your devices do not have a relative relay assign to a GPIO, If 1 button go with 1 relay that you will see it will send same topic with different index related to the relay number.

[wongnam]

My screen shot FYR, i hope it can help.

[mizrachiran]

Got it, that was my workaround - to define non existing relays.
However, if I want a specific device to act as a remote only it should be possible to configure only switches & buttons and achieve the same outcome.

[wongnam]

I don’t expect it will work with simple buttontopic method If you don’t assign relays.
It will work if you go with Rules :)

[ascillato]

Hi @mizrachiran

If your issue was solved, please close it. Thanks :+1:

[mizrachiran]

Closing this thread.
There are 3 options for those who want a Tasmota device to act as a remote control:

1. KNX, fast and very customizable.
2. MQTT define non existing relays and set StateTopic, will result in many redundant mqtt messages.
3. Rules - although it's working as expected, i find this option harder to maintain.

I ended up using KNX and it's working great so far.

[iliyang]

Sorry to revive an old thread, but I'm looking for a way to communicate between Tasmota devices as directly as possible, i.e. relying only on an active WiFi connections.

I haven't explored all possible options yet but it seems that the WebSend command (documented in this table) can be used to send commands from one Tasmota device to another? I'm thinking this could be particularly useful for implementing two-way light switching without the need for an MQTT broker on another middle man.

Does this make sense? Is there a better way to achieve such direct communication?

[lalo-uy]

Is doable with rules.
In order to do that you will need fixed ip or local names working in the
router.

El El mié, 8 de abr. de 2020 a la(s) 07:27, Iliyan Georgiev <
[email protected]> escribió:

Sorry to revive an old thread, but I'm looking for a way to communicate
between Tasmota devices as directly as possible, i.e. relying only on an
active WiFi connections. I haven't explored all possible options yet but it
seems that the WebSend command (documented in this table
https://tasmota.github.io/docs/Commands/#wi-fi) can be used to send
commands from one Tasmota device to another? I'm thinking this could be
particularly useful for implementing two-way light switching without the
need for an MQTT broker on another middle man. Does this make sense? Is
there a better way to achieve such direct communication?

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[iliyang]

That's exactly my idea. Thanks for the confirmation! Tasmota is awesome :)

[ascillato]

Direct communication between Tasmotas can be achieved by:

• Rules and websend command (HTTP API)
• MQTT publising in the cmnd/topic/ of the other device (MQTT)
• KNX (just enable the protocol. no extra hardware required - see docs at KNX)

[pcdiem]

A new option comes with a PR that was merged last night. You can use device groups to control one or more Tasmota devices directly using UDP. See Device Groups. The latest development release includes the DevGroupSend command that lets you send updates to a device group from a command.