Configuration
4.18 Data points
CP 1243-8 IRC
146 Operating Instructions, 02/2018, C79000-G8976-C385-03
The following relationship exists between the memory areas of the CP and the "Type of
transmission":
●
Static values are entered in the image memory (process image of the CP).
With DNP3 and IEC, static values correspond to the following classes:
– DNP3: Class 0
– IEC: Class 2
●
The values of data points configured as an event are also entered in the image memory.
The values of events are entered in the send buffer of the communications module in
addition.
With DNP3 and IEC, events correspond to the following classes:
– DNP3: Class 1 / 2 / 3
– IEC: Class 1
A data point is configured as a static value or as an event using the "Type of transmission"
parameter (see below).
The following types of transmission are possible:
●
Transfer after call (class 0)
The current value of the data point is entered as static value 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.
●
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,
see below)
– The value of a status bit of the status identifiers of the data point changes; see also
the section Status IDs of the data points (Page 141).
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 the generation of an event.
Events can be transmitted spontaneously; see below (Time of transmission).
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