Function description: Digital inputs/outputs
MSX-E1516
3.5
Watchdog
The Ethernet system
MSX-E1516
has a 16-bit watchdog, which is programmable in three time units
(
μ
s, 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.
3.6
Event logic
The event logic function (OR logic) enables event datagrams to be generated when the status of the
digital inputs or outputs changes.
On the web interface of the MSX-E system (see Chapter 4.1.1) or via the SOAP function
“MSXE1516__DigitalIOInitAndEnableEvent“, you can define the edge type of a specific channel for
which such a datagram should be generated.
When an event occurs, the Ethernet system provides the following information (see also Chapter 3.7):
•
Time stamp (optional)
•
“Source event mask”: Mask of the digital I/Os that generated the event
•
“Digital I/O Status“: Status of the digital I/Os when the event occurred.
Example
For each rising edge of the digital I/O 0 and for each falling edge of the digital I/O 1, an event
datagram should be generated.
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