Author Topic: detect 24VAC with zwave  (Read 1057 times)

Offline MarcusB

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Re: detect 24VAC with zwave
« Reply #15 on: May 15, 2018, 12:52:16 am »
The Fibaro rgbw controller does this. It has 4 12/24v outputs and four inputs. From memory the inputs are only 0-10v but thats easily fixed with two resistors acting as a voltage divider.
Vera can?t detect the inputs, but an input can be set at the unit to control one of the four outputs, so very can detect when an output goes high.
That way you can have four inputs.
I would suggest some cautions with this approach. The Fibaro unit is designed for DC operation. An AC signal applied to the analog inputs will need to be rectified and clamped to insure that the voltage seen by the inputs is never more than the 10 VDC limit, and never goes negative with respect to the Fibaro device circuit common. Capacitive  filtering should also be used to smooth out the AC waveform in order to get a reliable ON or OFF indication. For sensing an external AC voltage, I would rather use a relay or opto-coupler to maintain isolation between the AC source (whatever it may be) and the Z-Wave sensor.

You're right and it's good that you pointed it out.  I kind of figured if someone knew how to make a resistive voltage divider then they would know that AC needs to be rectified before being fed into a DC sensor.  It's similar to people saying to use a relay to trigger a sensor, but not warning about supressing back EMF on electronic circuits.

Offline HSD99

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Re: detect 24VAC with zwave
« Reply #16 on: May 15, 2018, 08:19:57 am »
It's not always easy to determine the level of someone's expertise on a forum (this or others). I tend towards the cautious side.  :)