I have a video security system that supports 16 power over Ethernet cameras (POE). The system also supports 16 external component inputs via Normally Open or Normally closed contacts NO/NC. The provides me with a way to set up door and window contacts as well as motion sensors. I even have my analog doorbell system set up to give me a signal. Even my mailbox has a sensor for open and closed door.
The 16 video cameras can be configured to alert you via email if someone or something crosses a defined area in the camera view. These alerts are are often unreliable because they are triggered by the wind, birds, and moving tree branches.
The devices on the 16 NO/NC inputs are solid and always give positive alerts and also send me emails when there is an alert from each of those 16 channels based on how you configure them.
The issue is that the video security system (aka NVR) has a very weak app. I can see the video live from the app. I can also replay recorded video. I can even turn video alerts on and off from the app. However, I can't control the external input alarms unless I log into the system. When I come home and start tripping devices my phone goes off like crazy with alerts and continues as I open and close doors and windows throughout the day.
So, I bought a 16 channel relay board for $15 dollars on Amazon and bought a single 12v relay for about $7 dollars that turns the 16 channel relay board on and off. I wired all my 16 alarm inputs from the various devices through the 16 channel relay. Plugged the single relay into the wemo and connect the single relay to the 16 channel relay board. Now I have a way to arm and disarm the 16 inputs. I can walk into my house and tell Alexa to turn off the system. This kills he power to the single relay pulling the 16 channels to ground and open. In this condition alarms can't go from the devices (door and windows sensors and motion sensors) to the NVR. I can tell Alexa to turn on the system when I leave which powers the single relay and switches all the 16 relays to closed and allows alarms to go through to the NVT. Or, if I forget to arm the system when I leave home I can turn it on via the wemo app.