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I/0 4 interference from Dual Relay


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hi, I have a simple setup next to the POOL that includes a POE powered Master brick with 4 bricklets.


2)Dual Relay (pool pump, pool lights)

3)Dual Relay (garden light, not used)

4)I/O 4port when I use 2 ports for manual switches for pool pump and pool lights


Now the trick is that when I connect my EV charger to the car (10A) that is on the same phase as pool pump. I/O ports will close for a short time as if the button would be pressed. This will start the pool pump and lights.


I'm guessing there is some interference from the Dual Relay going into the I/O 4port, but how is that possible? From an OH2 log I can see that i/o 4 putton press takes aboout 200ms, Any ideas how to mitigate such a problem?


2018-04-04 22:48:57.874 [itemStateChangedEvent     ] - Pool_in2 changed from OPEN to CLOSED
2018-04-04 22:48:57.881 [itemStateChangedEvent     ] - Pool_in3 changed from OPEN to CLOSED
2018-04-04 22:48:57.901 [itemCommandEvent          ] - Item 'Pool_Relay1_ligths' received command ON
2018-04-04 22:48:57.911 [itemStateChangedEvent     ] - Pool_Relay1_ligths changed from OFF to ON
2018-04-04 22:48:57.923 [itemCommandEvent          ] - Item 'Pool_Relay2_pump' received command ON
2018-04-04 22:48:57.925 [itemStateChangedEvent     ] - Pool_Relay2_pump changed from OFF to ON
2018-04-04 22:48:57.957 [DEBUG] [eclipse.smarthome.model.script.OTHER] - --------- Pool Pump Timer sleep time:7200000
2018-04-04 22:48:58.071 [itemStateChangedEvent     ] - Pool_in2 changed from CLOSED to OPEN
2018-04-04 22:48:58.076 [itemStateChangedEvent     ] - Pool_in3 changed from CLOSED to OPEN


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How do you detect the button press? Do you use the internal pull-ups from the IO-4 and the button shorts to ground?


If that is the case, you might want to add an additional pull-up (perhaps 1k or similar). The internal processor pull-up is specified to be somewhere between 100k and 400k, which might be to little resistance for the interference from the pump?

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  • 4 weeks later...

On I/O 4 I have a button that shorts The pin to board ground. Detection is done by Tinkerforge OpenHAB binding. I do not understand pull-up sugestion. You want me to add a 1Kohm resistor in the button circuit? The interference does happen if the button is  disconected and the I/O4 is simply conneted to the brick without any pin connected.


For now I have a rough workaround. Since the interference is shorting the pins for about 200ms. I wrote openhab rule that requires 2 sec button press to enable the pump or lights in Pool. But the problem is still there.

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