[SOLVED] How can i controll an item when this goes offline or online? And how do i loop a rule?

Setup, Configuration and Use Scripts & Rules
1

rule “Test2”
when

Item SETUP2 changed to OFF
then if (LED1.state == OFFLINE) {{
SETUP.sendCommand(OFF)}
createTimer(now.plusSeconds(5)) [
LEDSETUP1.sendCommand(OFF)]}
else if (LED1.state == ONLINE) {
SETUP3.sendCommand(OFF)}
end

That rule is basically what i want but is there a way to test if an item is online or offline?

rule “Test3”
when

Item SETUP3 changed to OFF
then if (LED1.state == ONLINE)
createTimer(now.plusSeconds(5)) [
LOOP ]} (loop until it goes offline)
else if (LED1.state == OFFLINE) {
SETUP.sendCommand(OFF)}
end

And how can i loop a rule so its always trying and when the result changed from online to offline it sends the command to the device i want?

2

Not clear what your Item is, a string perhaps?

That’s usually the wrong approach in OpenHAB. If you want something to happen when a change takes place, trigger the rule by the change.

3

Your rule triggers each time the item SETUP2 changed to OFF, if I’m not mistaken that behaviour is exactly what you are referring to by " loop a rule so its always trying…".
Such behaviour is called event-based programming.

4

Ok thanks i tryed and i made a loop and it works great, but how can i detect if my relay is online or offline or is that not possible?

1 Like
5

Tell us more about your “relay”. How is it bound to OpenHAB?

6

Is in the items folder

//Relay

Switch RELAY “RELAY” (LR,gLight)
{mqtt=">[mosquitto:cmnd/sonoff1/POWER:command:*:default],
<[mosquitto:stat/sonoff1/POWER:state:default]"}

7

Okay, presumably it’s a Sonoff device with maybe Tasmota software, communicating over MQTT.

I don’t know much about that, but if you want to detect the device going offline or unavailable, you would need it to be reporting in to OpenHAB regularly - so that you can look for the reports stopping. Does Tasmota do updates periodically, or only when the relay changes?

8

Yes its tasmota i think it does it periodically not sure.

9

If it does periodically update your Item, you can use the expire binding to set the Item to NULL if no update comes in for a time. Then trigger a rule from the change to NULL

10

{“Time”:“2018-07-04T22:39:06”,“Uptime”:27,“Vcc”:3.144,“POWER”:“OFF”,“Wifi”:{“AP”:2,“SSId”:“Batatas_EXT 2.4GHz”,“RSSI”:58,“APMac”:“E8:DE:27:4D:CB:11”}}

Yep the devices send this stuff after a while

I will try that i am gonna install that binding.

11

You’ll probably want also to set autoupdate=“false” for that Item, so that it’s state doesn’t get updated automatically by rules or UI trying to send commands to it.

12

When a Tasmota item goes offline (Disconnects with the wifi) the mqtt broker generates a Last Will and Testament message on the topic: tele/sonoff1/LWT

So create an item:

String Sonof1Online "Sonof 1 online status" { mqtt="<[mosquitto:tele/sonoff1/LWT:state:default]" }

Stick it in your sitemap and then unplug your sonoff, then plug it back in.
You should see the item going to OFFLINE and the ONLINE

Then a rule:

rule "sonoff offline"
when
    Sonof1Online changed to "OFFLINE"
then
    // Do what you want
end
1 Like
13

Out of interest, how does the MQTT broker “know” the subject has died? I guess there is some kind of keep-alive TCP traffic.

14

The sonoff client instruct the broker to leave a LWT (last will and testament) when disconnected
It’s a very nice feature of MQTT

15

What… you are right it actually does it holy potatoes thats awesome the rule i have created actually works with the offline and even tested it with online commands just needed to create that string very nice thanks a lot man.

16

That’s great, please like if you wnat and tick the solution mark. Thanks

17

Yes, I understood the Sonoff lodges a LWT with MQTT broker. I was wondering what triggers the MQTT broker to execute the LWT (apart from an obvious comms error).

Googling around it seems there is a keep-alive watch kept by MQTT broker, so detecting e.g. WiFi failure, as well as actual Sonoff failure. The keep-alive is actioned by the Sonoff client, I guess there’s a configurable timeout in there somewhere.

Note: this LWT method won’t detect any problems between OpenHAB and MQTT, or the broker itself failing. I’d expect there’d be other clues about that, though :slight_smile:

If you really needed checks on that as well, the periodic update + expire combination would be a way to do it within OpenHAB. An obvious way to do that would be to combine both methods - add expire=“5m,state=OFFLINE” or something like to the mqtt online Item you already described.

18

Yes that’s a possibility.
I have had my mosquitto running on a standalone pizero now for 236 days without failure and the same goes for wifi apart for a couple of resets of the router I did myself.
The UPS helped with a couple of brief power cuts too :smile: