Watchdog
Maintaining a reliable video-surveillance operation on a PC for several years is difficult. For example, mains electrical perturbations can lead to a failure in the PC using the video-surveillance system. Hence, manual intervention is required to restart it, but this will lead to video-surveillance operation breakdown due to the delay. To ensure that video-surveillance task is continuously monitored, a hardware device, called watchdog, is implemented on this frame grabber.
The watchdog is a hardware device which monitors the video-surveillance software application running on the PC. If there is no activity of the software application during a defined time, called time-out, the watchdog concludes in a system failure, and closes a PC reset relay which restarts the system.
The watchdog consists of two main devices, called monitors:
- The start-up monitor is responsible for monitoring the system when the computer is booting, and until the software application is launched.
- The application monitor is responsible for monitoring the system during the normal operation of the software application.
The monitors are based on a time-out mechanism. The software application must signal to the monitor that it is operational before a time-out period. If the application does not respond within this time-out period, the monitor will conclude that a system malfunction has occurred.