Configuration and operation
4.5 Telecontrol communication (CP 1542SP-1 IRC)
CP 1542SP-1, CP 1542SP-1 IRC, CP 1543SP-1
Operating Instructions, 01/2017, C79000-G8976-C426-03
71
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Some of the values of input data points with the scan priority "Low-priority" are read in
every scan cycle.
The number of values read per cycle is specified for the CP in the "Communication with
the CPU" parameter group with the "Max. number of read jobs" parameter. The values
that exceed this value and can therefore not be read in one cycle are then read in the
next or one of the following cycles.
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In every cycle, the values of a certain number of unsolicited write jobs are written to the
CPU. The number of values written per cycle is specified for the CP in the
"Communication with the CPU" parameter group with the "Max. number of write jobs"
parameter. The values whose number exceeds this value are then written in the next or
one of the following cycles.
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This is the waiting time between two scan cycles. It is used to reserve adequate time for
other processes that access the CPU via the backplane bus of the station.
Duration of the CPU scan cycle
Since no fixed time can be configured for the cycle and since the individual phases cannot
be assigned a fixed number of objects, the duration of the scan cycle is variable and can
change dynamically.
Data points are configured as a static value or as an event using the "Type of transmission"
parameter:
Saving the value of a data point configured as an event
Saving the value of a data point configured as an event in the send buffer (message
memory) can be triggered by various trigger types:
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The value of the data point is saved 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 73).
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The value of the data point is saved at configurable intervals or at a specific time of day.
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