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Help with understanding schematics

Discussion in 'Electronic Design' started by cameo, Mar 14, 2012.

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  1. cameo

    cameo Guest

    I am trying to set up a digital input trigger for a D-Link DCS-2230 IP
    camera and am not sure how to interpret the DI/DO schematics on page 58
    of the following PDF manual:


    According to the schematics, the digital input (DI) is to be applied to
    pin 2 that has the note: "A switch from DI to DC 5 V, activated by
    setting NO, or NC."

    The type of DI (whether NO or NC) is set by the cam's software, as shown
    on pg. 48 of the same manual.

    Then on the bottom of pg. 58 there are two schematics for "Internal 5V
    Power" and "External 3-12 V Power."

    Could somebody just cut through the fog here and tell me what two pins I
    need to connect to an external relay and whether that relay needs to do
    just a close or open (based on the cam's NO/NC setting) or whether that
    relays should actually apply some low voltage to the pins of the cam?
    This schematics is a bit over my head, I'm afraid. Thanks.
  2. DA

    DA Guest

    responding to
    DA wrote:

    cameo wrote:

    Looks like your input is between pins 2 (DI) and 3(5VDC). The camera
    itself supplies the 5VDC power (says the manual - I didn't use this
    camera). So, your trigger device (reed switch for example) breaks the
    circuit and the input goes low, that's how the camera knows it's tripped.

    Things in security are usually NC (normally closed) for in case when the
    evildoer du-jour rips the cable off and the trigger cannot close it
    anymore but the destruction of the cable creates an open (naturally) by
    itself and so the alarm gets tripped anyhow. Hopefully this is not a
    battery-powered setup because NC circuits tend to draw some power (though
    it can be very small).

    Good luck!
  3. cameo

    cameo Guest

    Thanks. Actually, my trigger will be an X-10 actuator module that
    provides a normally open trigger. What caused the biggest confusion for
    me was the bottom right "External 3-12 V Power" schematics that seems to
    duplicate the one on bottom left for "Internal 5V Power." The DCS-2230
    camera does come with its own power supply, so I don't get what that
    external power schematics is there for. Could it be for the DCS-2210
    model that is essentially identical to DCS-2230 except it is wired-only,
    using PoE. This manual is for both models though the differences are
    usually pointed out in the manual. In this case there is no word about that.
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