Siemens SIMATIC S7-1200 CP 1243-8 IRC Operating Instructions Manual page 149

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 (frame memory)
can be triggered by various trigger types:
● Threshold value trigger
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 150).
● Time trigger
The value of the data point is saved at configurable intervals or at a specific time of day.
● Event trigger (Trigger tag)
The value of the data point is saved 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 a trigger tag is in the bit memory or in a data block, the CP resets
the trigger variable itself to 0 (zero) as soon as the value of the data point has been
transferred. This can take up to 500 milliseconds.
Note
Fast setting of triggers
Triggers must not be set faster than a minimum interval of 500 milliseconds. This also
applies to hardware triggers (input area).
Note
Hardware trigger
You need to reset hardware triggers via the user program.
Time of transmission of a triggered data point (event)
With the DNP3 and IEC protocols, the spontaneous transmission of events depends on
whether spontaneous sending or asymmetric communication is possible in the network.
With the ST7 protocol, you define the time using the "Transmission mode" parameter.
CP 1243-8 IRC
Operating Instructions, 02/2018, C79000-G8976-C385-03
Configuration
4.18 Data points
149