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Do POE cameras with Motion Detect need a 2nd cable?

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I'm building my first system. It's for a job site (home remodel) to prevent tool theft. It'll be installed temporarily, then reconfigured during the job, as walls are built, plumbing, wiring, sheetrock, etc. Later, the system will be broken down and moved to the next job site. The point is, wires are a headache. The fewer, the better.


I'll use a mix of POE and WiFi cameras. Motion Detect (MD) is important. I'm using a Dahua NVR4116 and Dahua IPC-HDBW4421E-AS Dome IP Camera (more cams soon).


The MD output from the camera is an open collector output to a wire coming out of the camera. So my POE camera will have a Cat6 cable for data & POE. And a 2nd cable to carry the MD signal from the camera back to the NVR's Alarm input. The NVR will send an SMS to the General Contractor (GC) and work crew.


This 2nd cable w/ MD alarm is a drawback. Like I said, wires on a job site are a headache for the GC and others.


I has assumed the MD alarm would be sent to the NVR as data, using the Cat6 cable. Similar to how audio (I assume) is part of the data stream to the NVR. Sending the 3.3V open collector signal over a long run of cable seem problematic also, as compared to sending MD event as IP data.


The MD capability of the camera is pretty sophisticated and programmable. I really want to take advantage of it. I also assumed the MD event would be part of the being recorded, ie superimposed on the video.


- Am I missing something?

- Do cameras that support MD, Audio in/out, and audio alarms really need a dedicated cable?

- Are all 8 conductors in the Cat 6 cable used? It's not a Gb camera, so maybe it uses only 4 of the 8 conductors? (allowing me to re-purpose spare conductors)

- A cable to carry camera alarms really defeats the purpose of a WiFi camera with MD...


Thanks for any help!


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Normally motion detection is sent as data, the alarm outputs on the camera are generally to trigger a physical device (relay, light, chime, etc.). Same with the alarm inputs on the NVR, they are generally to receive a signal from a physical device.

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