Shelly Pro 2 – Input not changing state in Detached mode

    • Autor

    Hello,

    I have an issue with a Shelly Pro 2.

    I wired it according to the wiring diagram, using a 1 MΩ resistor.
    In the settings, it is correctly configured as Detached – Input is separated / not changing state of the output/relay, and the input type is set to Switch.

    Here is what I observe:

    • When the alarm is not activated, I measure about 50 V between earth (ground) and SW1.
    • When the alarm is activated, the voltage rises to about 120 V between earth and SW1.

    My electrical installation is 3 × 220 V.

    The issue is the following:

    • When I access the Shelly web interface (192.168.1......), without the alarm, the input is shown as OFF.
    • With the alarm activated, the input still remains at 0 and does not change state.

    I therefore do not understand why the input does not switch despite the measured voltage change.

    Thank you in advance for your help.

    Best regards,
    Jean-Pierre

    Please measure the current flowing out of SW1 (or SW2) with alarm contact closed and/or open!

    Second test: remove the resistor and check the current again (with both states of alarm contact).

    „Habt Geduld. Alle Dinge sind schwierig, bevor sie einfach werden!“ (aus Frankreich)

    „Nothing in life is to be feared, it is only to be understood.“ (Marie Curie, 1867-1934)

    „Comment is free, but facts are sacred“ (C.P. Scott, britischer Verleger)

    • Autor

    With the resistor in place, when the alarm contact is closed and SW1 is activated, the measured voltage is 213 V.
    When the alarm contact is open, the voltage drops to 95 V.

    Without the resistor, the measured voltage with the alarm contact closed is 234 V, while with the alarm contact open, it is 82 V.

    Thanks für the new measurements! But I asked for current (in milliamperes), not for voltage figures!

    Nevertheless, with the additional voltage figures, we may determine that the circuit diagram given at the Toscano device is obviously wrong:

    Der Inhalt kann nicht angezeigt werden, da Sie keine Berechtigung haben, diesen Inhalt zu sehen.

    Please have a look at the orange frame: Most likely, the „level“ contact doesn’t switch with neutral, but with live potential! Otherwise the wiring may be different and neutral potential isn’t attached to terminal „OV“!?

    In this case, the resistor must be omitted to ensure proper operation.

    „Habt Geduld. Alle Dinge sind schwierig, bevor sie einfach werden!“ (aus Frankreich)

    „Nothing in life is to be feared, it is only to be understood.“ (Marie Curie, 1867-1934)

    „Comment is free, but facts are sacred“ (C.P. Scott, britischer Verleger)

    • Autor

    I removed the resistor. The operation is correct: I get an ON when the level is low and an OFF when the level is high.
    Therefore, on the outputs of the Toscano Level and Alarm module, no resistor is required.

    Einmal editiert, zuletzt von JPCanard (6. Februar 2026 um 14:51)