Configuration and operation
4.9 STEP 7 configuration
CP 1242-7 GPRS V2
Operating Instructions, 10/2016, C79000-G8976-C311-02
69
Generation of events if a data point status changes
With data points that were configured as an event, the change to the status bit of the status
identifiers described below also leads to an event being generated.
Example: If the value of the status "RESTART" of a data point configured as an event
changes form 1 (value not yet updated) to 0 (value updated) when the station starts up, this
causes an event to be generated.
Data point index
Configuration of the data point index
Within a CP, the indexes of the data point classes must comply with the following rules:
● Input
The index of a data point of the type input must be unique throughout all data point types
(digital inputs, analog inputs etc.).
● Output
– A data point of the type output can have the same index as a data point of the type
input.
– Several data points of the type output can have the same index.
Note
Data points for the inter-station communication with a CP in another S7 station
Note that for inter
-station communication, the indexes of the two corresponding data points
ta point pair) must be identical for the sending and receiving CP, see also section
(Page 82).
Read cycle
Priority of the data points
The cyclic reading of the values of input data points from their assigned PLC tags on the
CPU can be prioritized.
Less important input data points do not need to be read in every CPU scan cycle. Important
input data points, on the other hand, can be prioritized for updating in every CPU scan cycle.
You can prioritize the data points in STEP 7 in the data point configuration in the "General"
tab with the "Read cycle" parameter. There you will find the two following options for input
data points:
● Fast cycle
● Normal cycle
The data points are read according to the method described below.
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