Siemens CP 1243-1 Operating Instructions Manual page 99

Types of transmission / event classes
The following types of transmission are possible:
● Transfer after call
The current value of the data point is entered in the image memory of the CP. New
values of a data point overwrite the last stored value in the image memory.
After being called by the communications partner, the current value at the time is
transferred.
● Triggered (event)
The values of data points configured as an event are entered in the image memory and
also in the send buffer of the CP.
The values of events are saved in the following situations:
– The configured trigger conditions are fulfilled (data point configuration > "Trigger" tab,
– The value of a status bit of the status identifiers of the data point changes see also the
When data points are configured as an event via the "Type of transmission" parameter,
the following event classes are available:
– Every value triggered
– Current value triggered
Trigger
Trigger types
Various trigger types are available for 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 101).
● Time trigger
The value of the data point is transferred at configurable intervals or at a specific time of
day.
CP 1243-1
Operating Instructions, 04/2017, C79000-G8976-C365-03
see below)
section Status IDs of the data points (Page 95).
Example: When the value of a data point configured as an event is updated during
startup of the station by reading the CPU data for the first time, the status "RESTART"
of this data point changes (bit status change 1 → 0). This leads to generation of an
event.
Each value change is entered in the send buffer in chronological order.
Only the last current value is entered in the send buffer. It overwrites the value stored
there previously.
Configuration
4.10 Data points
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