Run Mode - Siemens SIMATIC S7-1500 System Manual

Commissioning
10.5 Operating modes of the CPU
10.5.3

RUN mode

Function
In "RUN" mode the cyclic, time-driven, and interrupt-driven program execution is performed.
Addresses that are in the "Automatic Update" process image are automatically updated in
each program cycle. See also the Process images and process image partitions (Page 90)
section.
Execution of the user program
Once the CPU has read the inputs, the cyclic program is executed from the first instruction to
the last instruction.
If you have configured a minimum cycle time, the CPU will not end the cycle until this
minimum cycle time has expired, even if the user program is completed sooner.
A cycle monitoring time is set to ensure that the cyclic program is completed within a
specified time. You can change the cycle monitoring time to suit your requirements. If the
cyclic program has not finished running within this time, the system responds with a time
error.
Further events such as hardware interrupts, diagnostics interrupts and communication can
interrupt the cyclic program flow and prolong the cycle time.
Reference
Further information about cycle and response times is available in the Function Manual
Cycle and response times (http://support.automation.siemens.com/WW/view/en/59193558).
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Automation system
System Manual, 12/2014, A5E03461182-AC