Fermax VDS 2451 the definitive thread?

I am here trying to use my brand new Nuki Opener with a Fermax 2451 VDS (kinda old model, much common in Spain).

I’ve seen several discussion about setting up the cabling and stuff, but could not make my head around such rigmarole of trials, errors, firmware updates, cable colors, and differing advice.

I guess a lot of Nuki owners are giving up and just returning their Openers because I’ve never seen such an immature state in a (supposedly marketable) product.

So, how come one cannot make it work without at least a couple hours worth of stress and technical issues?

This is a kinda old, basic VDS “compatible” interphone which is the digital bus 3-wire variety. To start with, the colors of these 3 wires coming to the interphone from the outside world are just anyone’s guess.

I’ve never seen a clear, definite explanation about what the A-,A+, Bus+, Bus-, -, + on their own, L symbol etc. are supposed to refer to, or be wired to…

Can someone explain in plain terms? Believe me, I’ve got kind o knowledge about gadgets all kind, even program my own uCs/ Arduinos to try to integrate home automation solutions to my taste. But THIS… oh well THIS is not up to anything resembling a company’s good practice in regard to their products’ installation procedures NOR support thereof!!!

There was some “Michel” out there sorting out his own problems. Apparently he came out with a solution but was not clear enough pointing out how he did succeed finally, I guess it was just a drop of “firmware update” sheer luck ???

Please! I am desperate and thinking of returning my Nuki!


Hola! Te contesto en español, que ya me canse.

Yo hoy Justo he pedido mi devolución del opener a Amazon. He instalado wi-box de Fermax y a la primera, es diferente pero me sirve.

Es la primera vez que me rindo con un producto comercial. Smart lock, perfecto. Opener, un desastre. No me pude hacer con el.

Tienes mucha razón en tus palabras.




I’ve been building my “openers” with two relays and a wifi activated socket for many years now. The Fermax that you mentioned gave me a headache for very long time in some of the locations (1st floor all good, 4th floor no way to make it work). The problem was related to the voltage being different in different apartments, so, from the nominal 5 volts signal, in some cases it was reduced to 3, which was enough to make the bell ring but the relay won’t trigger. I can imagine the Nuki has the same issue.


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Hello Gerardo.

When you say “my openers” does it mean you resorted finally to some customized, personally wired or managed solution?

It gets so frustrating trying to make the Opener work with BOTH Fermax 2451 AND 3390 (which I bought yesterday but didn’t succeed either), that sometimes I get the temptation of ditching the Opener altogether and trying to build myself an Arduino-like controller (a “button pusher” simulation if you wish).

That way I wouldn’t have to deal at all with L, +, -, the color codes, the app setup, all that rigmarole… I mean, the bell ringing CAN be detected electronically, the door opener button CAN be actuated electronically (think a relay), as well as the mic+ear set being hung/ not hung state (which is another pushbutton of sorts).

So what would detract me from making out my own solution? (I am not talking of course still about securing my own app, making the “app” visible to just myself from outside home and all those additional or securing details).

Does anyone out there know how to make the Fermax 3390 (vds) work with Opener?? I’ve not got it working yet. I’m opening another thread/ ticket for this.

Too SAD a product like this is advertised as something that doesn’t DELIVER in the end… it’s too close to being a case of commercial fraud I guess…

Hola, conseguiste hacer funcionar al final el opener con el 2451?