Alarm I/O LED Floodlight

Discussion in 'NVR's, DVR's & Computers' started by h901, May 18, 2017.

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  1. h901

    h901 Getting the hang of it

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    hi

    this question may come across stupid but i've never used the i/o ports on a camera before so don't really know what their limitations are. would it be possible to connect a LED floodlight to the i/o ports so when for example the camera detects motion is can turn on the floodlight?

    thanks
     
  2. Fastb

    Fastb Getting comfortable

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    Check your camera's specs. The alarm output is probably a pair of relay contacts. You can configure the contacts to be NO or NC.
    Also, the spec will state how much current the contacts can handle.
    I used the alarm output to turn on a flashing strobe light located near the cam (and far from the NVR). It worked great. My strobe light wasn't power hungry, and the contacts handled the current.
    The camera DOES NOT power the light. The alarm output is simply a set of contacts.
    I ran two conductor cable to the cam & light, to provide 12V. The alarm output simply passes the 12V to the light after an "Event"
    If your LED floodlight requires more current than the cam alarm i/o can provide, you'll need a slave relay.

    Good luck!

    Fastb
     
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  3. alastairstevenson

    alastairstevenson Known around here

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    Sorry to disagree, but that's not likely to be the case for the (unspecified) camera. It's much more likely to be a simple uncommitted (ie open collector or open drain) electronic switch that conducts to GND when active.
    A safe, and effective, approach that will also protect against any mains-related side effects from the load side would be to use an opto-isolator.
    These are designed to be operated by alarm outputs that can sink just a few mA, and usually have high-power switching capability for multiple load types, and are widely available at low prices.
     
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  4. Fastb

    Fastb Getting comfortable

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    alastairstevenson,

    I'm glad you disagreed, and commented on an open collector or drain. You were right. Here'ss the info from the camera's Quick Start Guide. https://www.google.com/url?sa=t&rct=j&q=&esrc=s&source=web&cd=5&ved=0ahUKEwiziJz77_zTAhVI8GMKHeqlCCYQFgg5MAQ&url=http://support.dahuasecurity.com/upfile/pic/201507/Dahua%20HD%20IR%20Vandal%20Proof%20Network%20Dome%20Camera%20%20User%27s%20Manual%20.pdf&usg=AFQjCNGNlFQERQxEENkF9mjafrcbJC2Faw&sig2=nB4K9ofXNDGq51MXMfGsww&cad=rja

    upload_2017-5-19_14-23-22.png

    I think I confused the relays for Alarm Out on the NVR with the alarm out of the cam.
    After I found the above circuit diagram, it jogged my memory further. Using the cam to turn on my strobe light had limitations:
    - can't source current, only sink the current
    - 30ma is a limitation
    - my strobe needs 120ma, and 6 to 12 volts.
    But more importantly:
    - the camera "alarm on" time isn't programmable, unlike the "alarm on" time duration of the NVR. I wanted the stobe to fire for much longer than the "Event", ie: IVS or MD
    - also, disabling the alarm out (ie: my strobe light) is easy on the NVR. So I could disable the light if I was expecting people to visit.

    Since I'd need a 2nd cable to the cam, it might as well run back to the NVR, to use NVR alarm out.

    h901, sorry for the misinformation about cam alarm out. The info relates to NVR alarm out.

    Fastb
     
    Last edited: May 19, 2017
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  5. alastairstevenson

    alastairstevenson Known around here

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    That's good and helpful detail.
    Space and size limitations alone would be a reason why a relay would not feature in a camera - less so though in an NVR.
    Plus - an electronic output would already exist as a pin on a GPIO, so would be cheaper.
    Opto-isolators are the swiss army knife of power interfaces - avoiding lots of potential problems.
     
  6. h901

    h901 Getting the hang of it

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    Thanks guys.

    Is it easy to use an opto-isolator or should I just avoid it. My brother is an electrician so I can ask him about mains wiring but he's not too familiar with electronics
     
  7. alastairstevenson

    alastairstevenson Known around here

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    Very easy to use. And plenty of choice at low prices.
    The input side is low voltage, and just requires the ability to sink a few mA from typically 5V to activate.
    The output side varies with the intended load - could be a triac (solid state relay) or an actual clunk click relay (electromechanical) for heavy mains loads.
    And as it's light that couples them together, no worries about mains power getting in about your camera and blowing it up.
     
  8. h901

    h901 Getting the hang of it

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    Thanks for your help.

    I still don't really understand it exactly, apologies. I've got a 20w LED floodlight, how would I connect it up to the camera and mains using the opto-isolator?

    The camera is a Dahua ptz SD6AL230F-HNI
     
  9. Fastb

    Fastb Getting comfortable

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    What voltage does the floodlight need?
    I suggest a test, to check how long the light will be on. If it's only as long as the "Line Cross" if using ICS, or only as long as a Mot Detect event, will you be happy with a 1 to 4 second floodlight?
     
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  10. h901

    h901 Getting the hang of it

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    The floodlight takes 230v. The plan was if the trip wire is crossed to activate the flood light for around 30seconds to a minute. I don't want to use a light with a pir as it'll go off all the time due to cars driving past if that makes sense