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Posts: 3
Registered: ‎05-11-2018

Wemo Maker Garage Opener - Sensor trigger with 24V input

Hi all. Thanks for the excellent community. I'm late in the party and just started my garage door opener project.


I am able to trigger my door with the relay, however I'm struggling with the sensor due to my lack of knowledge in electronic circuits.


My garage door is controlled by a FAAC E721 device. It has an output pin (Output 1) that can be programmed to 24v whenever the door is closed. Its value is supposed to be 0v otherwise. Therefore I do not want to add an additional sensor in the way and would like to use that information to trigger my Maker sensor.


Thanks to some earlier posts (specifically: http://community.wemo.com/t5/WEMO-Hardware/help-making-a-5v-power-plug-act-like-a-sensor-for-Maker/m...), I Came up with the following solution:



It actually worked on the bench:

 - if I completly switch off the 24V power supply the sensor appears as 'not triggered'

 - if the power supply is switched on to 24v the sensor appears as 'triggered'


However when I installed it in the actual FAAC, the sensor is always 'triggered', whatever is the status of the door. I checked Output 1 and its value is close to 0 when the door is open (or opening) but not quite - e.g. some value < 1v.


Would you have any advice?


Thanks in advance!


WEMO Maker Inventor
Posts: 1,705
Registered: ‎06-14-2014

Re: Wemo Maker Garage Opener - Sensor trigger with 24V input

The specs on the Maker say the maximum you should apply to S is 5V.


Did you connect a reasonably good ground wire between the door opener and the Maker "-"?


I'd be very tempted to condition the input to 5V with a simple circuit as mentioned in the link you referenced, if the door does fail to go to 0V you can adjust for it there.

Posts: 3
Registered: ‎05-11-2018

Re: Wemo Maker Garage Opener - Sensor trigger with 24V input

Hi Mike, thanks or your answer. I do not know if the drawing showed up therefore I'll try to describe in text:


FAAC Output1 + (0 or 24V)  --> Resistor 36K --> Transistor 2N2222 B pin

Transistor C pin --> Maker S (5V)

Transistor E pin --> Maker - and FAAC Output1 -


So as far as I understand the Maker would not get the 24 V because of the transistor in between; It should be pretty similar to what you described in the linked post. Too bad I do not know how to add a pic to my post...


My wires are all the same, quite thin, I'll check their specs later. In the meantime I'll try to post the pic one more time:





WEMO Maker Inventor
Posts: 1,705
Registered: ‎06-14-2014

Re: Wemo Maker Garage Opener - Sensor trigger with 24V input

That drawing looks good and yes this would isolate the input.  You should be seeing around 0.3V on S when the transistor is active.


If not, make sure the transistor and resistor are close to the Maker with short leads (vs being closer to the door opener).  I'm not sure about the output impedence of the S, it might help to connect a 10K resistor (or whatever you have around over 1K) between the Maker "+" and the S / Transistor C.  But I don't think this is necessary, I think the maker has an internal pullup, shown here: http://community.wemo.com/t5/WEMO-Hardware/WeMo-Maker-Technical-Specifications/m-p/1748/highlight/tr....  A low for S is 0.8V or less.


If you are seeing 0.3V at S, try shorting S to ground with a jumper to confirm the maker is still working.  It may be that the belkin app itself isn't showing the sensor properly...  If you've got a PC you could use my java application (it's free) to check the status of the Maker without worrying that the belkin app is in the way. 



Posts: 3
Registered: ‎05-11-2018

Re: Wemo Maker Garage Opener - Sensor trigger with 24V input

Hi again,


I made a few adjustments and some progress:

Changed resistor from 36K to 450K (which allows me to trigger the maker with more voltage)

Actual measurement shows that the output is more 27V than 24V as advertised

FAAC E721 MAKER v2.png

With this setup, when I test it on my desk, I can trigger the maker sensor by varying the input voltage:

 - if voltage > 3V (roughly) then the sensor is triggered (same if voltage is 27V)

 - if voltage < 3V (roughly) then the sensor is not triggered


Now my new issue:

If nothing is plugged to the E721 (the garage door controller circuit), my measurements show that I get 27V on Output 1 when door is closed, and 0,3V otherwise.

When I attach my new setup to the Output 1 pinout, the output voltage immediately switches to 27V no matter what the status of the door is.


Link to the E721 user guide: http://trade.electricgatesuk.net/wp-content/uploads/2016/02/E721-Manual.pdf

Relevant extract (My setup is 06):

E721 programmation Level 2.png


Any idea why this setup is not working as expected?

Thanks in advance.


WEMO Maker Inventor
Posts: 1,705
Registered: ‎06-14-2014

Re: Wemo Maker Garage Opener - Sensor trigger with 24V input

Hard to tell, there's a few inconsistencies in what you're seeing here.


This spec says output 1 is "Open Collector" (OC) which means it isn't driven from the opener side at all, it's only pulled to ground when active.  Configured to 06 it should be 0V (or probably about 0.3V) when the gate is closed.  Internally it's essentially a duplicate of the transistor circuit you've added externally.  When the gate is open it's probably floating to 24V/27V, but the exact value doesn't matter.


Also, in your circuit, the value of R1 doesn't matter much, you just want it big enough to limit the current flow.  27V/36K is less than 1ma which was fine.


But I suspect the problem here is that you can't use an OC output to turn on the transistor Q1, and the larger you make R1 the worse it will work...  In fact if that spec is correct you don't need the transistor at all. 


To check (in case something is broken on the opener side), connect the gnd wires, and connect the opener output 1 through a resistor (36K is fine) to Maker +.  Then measure the opener output 1 side of the resistor.  It should read +5 when the gate is open and < 0.5V when the gate is closed.  If this works, you only need a pair of wires from the opener to the Maker.  Opener gnd to Maker gnd, Opener output 1 straight to Maker S.  Maker S has an internal pullup to +5 (Maker +).  Q1 and R1 can be eliminated.