Siemens S7-1200 - Page 53

Configuration and operation
4.8 Process image, type of transmission, event classes, triggers
CP 1243-7 LTE
Operating Instructions, 01/2015, C79000-G8976-C381-01
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Trigger
Various trigger types are available for starting event-driven transfer:
●
Threshold value trigger
The value of the data point is transferred when this reaches a certain threshold. The
threshold is calculated as the difference compared with the last stored value, refer to the
section Threshold value trigger (Page 78).
●
Time trigger
The value of the data point is transferred at configurable intervals or at a specific time of
day.
●
Event trigger
The value of the data point is transferred when a configurable trigger signal is fired. For
the trigger signal, the edge change (0 → 1) of a trigger tag is evaluated that is set by the
user program. When necessary, a separate trigger tag can be configured for each data
point.
Resetting the trigger tag in the bit memory area / DB:
If the memory area of the trigger tag is in the bit memory or in a data block, the trigger tag
is reset to zero when the data point value is transferred.
You specify whether the value of a data point is transferred to the communications partner
immediately after the trigger fires or after a delay in the "Transmission mode" parameter.
Transmission mode
The transmission mode of a frame is set in the "Trigger" tab of the data point. With the two
options, you specify whether frames of events are sent immediately or following a delay:
● Unsolicited
The value is transferred immediately.
● Conditional spontaneous
The value is transferred only when one of the two following conditions is fulfilled:
– The communications partner queries the station.
– The value of another event with the transmission mode "Unsolicited" is transferred.