Integrating BFT Thalia Gate Operator with Shelly Uni for AC/DC Detection

Hey, that's the situation:

- BFT Thalia light gate control panel to be controlled/read by Shelly Uni
- The control panel output for accessories gives 29V AC (it should be 24V AC ). This is unfortunately too much for Shelly, so I connected it via a separate 12V power supply DC . So I have AC on the control panel and DC on Shelly. Controlling the switchboard with this current works for me, worse with reading the switchboard --> Shelly
- the control panel on ports 20/21 gives power to the warning light - current flows when the gate leaves move; this is the aforementioned 29VAC accessory current
- I would like to detect this current with a binary sensor from Shelly; this is (I think) a "reed sensor", its designation is IN_1 or IN_2 (there are 2 such sensors): consists of a single connection to the circuit, which should detect a binary state of 0 or 1
- Unfortunately, my Shelly powered by 12VDC, does not detect 29VAC. My guess is that it can only detect the current it is supplied with (does this make sense?).
- so I came up with the idea of inserting a relay between ports 20/21 and the Shelly, which would switch on from 29VAC, while on power/transmission it would have 12VDC, which I would take from "my" 12VDC power supply (and switching would be from the control panel)
With a standard 5 pin relay it would look like this:
85 and 86 - 29VAC from the control panel
30 - "plus" from the 12VDC supply
87 - diode and to the 'minus' of the 12VDC supply, and somewhere in there attached sensor IN_1 from Shelly

Does this make sense and a request for a suitable relay. The currents are small: AC is 5W max, and DC as much as the diode. Or alternatively, how else to embrace this. Below are the schematics.

sh.jpg Download (18.9 kB) bft.jpg Download (97.23 kB)

Leaving the subject of AC/DC aside - the control panel has an AUX3 output (terminals 26/27) which it controls, but it does not power. It can be set, for example, to be closed when the gate is closed and at other times, open.

So that's what I did, I pulled the plus and minus there from the 12V DC power supply and one "reed sensor". I was afraid that this might overload the power supply, so I gave the circuit a 12V bulb. Everything was OK, the sensor was detecting voltage when it needed to, and the bulb was not lit. I concluded from this that there was a safety feature on the control panel side so that it wouldn't take power. So I knocked the bulb out and zonk: Shelly doesn't turn on at all, as if the power supply has just been overloaded. I reinstated the bulb - it works.

Can someone explain this niggle to me? What should I plug in there to make it work long term (a car bulb, even though it doesn't light up, is probably not the best choice). Thanks in advance .