Operating Mode Transitions - Siemens SIMATIC S7-1500/ET 200MP System Manual

Commissioning
12.5 Operating modes
Execution of the user program
Once the CPU has written the outputs and read the inputs, it runs through the cyclic program
from the first instruction to the last instruction. Events with higher priority, such as hardware
interrupts, diagnostic interrupts and communication, can interrupt the cyclic program flow
and prolong the cycle time.
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.
The operating system monitors the execution time of the cyclic program for a configurable
upper limit known as the maximum cycle time. You can restart this time monitoring at any
point in your program by calling the RE_TRIGR instruction.
If the cyclic program exceeds the maximum cycle time, the operating system starts the time
error OB (OB 80). If the OB is not present, the CPU ignores that the maximum cycle time was
exceeded. If the cycle monitoring time is exceeded a second time, e.g. while the time error
OB is being processed, the CPU goes to STOP mode.
Reference
Additional information about cycle and response times is available in the Function Manual
Cycle and response times (https://support.automation.siemens.com/WW/view/en/59193558).
12.5.4

Operating mode transitions

Operating modes and operating mode transitions
The following figure shows the operating modes and the operating mode transitions:
Figure 12-3
268
Operating modes and operating mode transitions
Automation system
System Manual, 01/2023, A5E03461182-AK