Watchdog Block Diagram
The block diagram of the watchdog is shown below.
Watchdog block diagram
The above block diagram connects with three inputs and one output:
- Power On: the watchdog requires the power supply of the monitored PC. At Power On, the watchdog is operational, and starts to monitor the system.
- StartupTimeout: the software application is responsible to adequately define a maximum time. It allows the system to complete the start-up sequence by setting the StartupTimeout element.
- ApplicationTimeout: the software application is responsible to adequately define a maximum time. It allows the application to periodically signal its correct operation by setting the ApplicationTimeout element.
- PC reset connector: when the watchdog concludes that the start-up has failed, or that the application is no longer running, it restarts the system by closing the PC reset relay. For this purpose, an electrical connection has to be installed between the PC reset relay and the reset connector of the PC motherboard.