Rule: change when relais gives contact (sadly active low relais)

Setup, Configuration and Use Scripts & Rules
#1

Hi,
i have a relais, which is giving a signal for 1 second to open the frontdoor. Sadly this relais is active low. So when i remove power, the relais changes automatically to CLOSED and my door opens…

When i give back the power, the relais changes to OPEN again.

Is there a way to do this with a rule? I want prevent my frontdoor from opening, when the power of the relais is gone.

My current rule is like this:

rule "frontdoor"
	when
		Item Kontakt_Haustuer changed to CLOSED
	then
		Haustuer_Dummy.sendCommand(ON)
end

Is there a way to change the rule, that it only opens, when the contact was only closed for about 500ms? Maybe with timers?

I know, it is not the best way, because if the power is gone only for very short time, the door will open too, but it would be a workaround for the first time, until i can find a better solution for this.

#2

In the rule you can use Thread::sleep(500) then check the condition with an if statement.

I’m not sure how the item Kontakt_Haustuer works. Does this CLOSE then change back to OPEN fast? If so here’s a rule example:

rule "frontdoor"
	when
		Item Kontakt_Haustuer changed to CLOSED
	then
                Thread::sleep(500)
                 if(Kontakt_Haustuer.state != CLOSED) // check the item has changed from CLOSED state
		Haustuer_Dummy.sendCommand(ON)
end
#3

Yes, it closes and opens again about 500ms later.

Can i do this with a timer too?

#4

Yep, you want a timer in the rule or use the Expire binding?

#5

Timer in the rule example:

var Timer doorTimer = null
rule "frontdoor"
	when
		Item Kontakt_Haustuer changed to CLOSED
	then
               doorTimer = createTimer(now.plusSeconds(1), [ | 
               if(Kontakt_Haustuer.state != CLOSED) {
		Haustuer_Dummy.sendCommand(ON)
                doorTimer = null
                }
           ])
end

If one second is to long replace now.plusSeconds with now.plusMilliseconds(500) and adjust the value as needed.

1 Like
#6

Thanks, will test it.

#7

This should work except when you have a power blip (quick on off). Is using a small UPS power supply possible? Just something that will keep the sensor powered for a few minuets, as the rule will only run when the item has changed to OFF.

#8

This will be no rule for very long time. My relais card can send MQTT too. But it isn´t working yet, i don´t get any data into my openhab-item…

See my other post:

When MQTT is working, i can remove the wires from my relais and use only the MQTT data.