Watchdog - Addi-Data MSX-E1701 Technical Description

Function description: Digital inputs/outputs

4.5 Watchdog

The Ethernet system MSX-E1701 has a 16-bit watchdog, which is programmable in three time units
(μs, ms, s). The watchdog is used to reset the digital outputs to 0 V after a specific time.
Operation of the watchdog
1. After the system reboot, the watchdog is in "Uninitialised" state.
It can be initialised and activated ("Running" state) over the web interface of the MSX-E system or
by a software function.
2. With the first write access to the outputs, the watchdog is started: The watchdog time is loaded
and the watchdog starts counting down.
As long as the watchdog time has not elapsed, the watchdog is triggered with every further write
access to the outputs, i. e. the watchdog time is reloaded.
3. When the watchdog time has elapsed, the watchdog is put in "Overrun" state and all digital
outputs are set to 0 V or 0 mA. In "Overrun" state, any write access to the outputs is ignored.
4. To re-enable write access, the watchdog first has to be put in "Stopped" state (web interface) or
deactivated by a software function.
To reactivate the watchdog, it has to be put in "Running" state again or reinitialised and
reactivated by a software function.
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MSX-E1701