Stop Mode; Run Mode - Siemens SIMATIC ET 200SP System Manual

Example for the "Comparison preset to actual configuration" parameter
"Startup CPU only if compatible":
The input module DI 16x24VDC ST with 16 digital inputs is a compatible replacement for the
input module DI 8x24VDC ST with 8 digital inputs, because the pin assignment and all the
electrical and functional properties match.
"Startup CPU even if mismatch":
Instead of a configured digital input module, you insert an analog output module or no
module is present in this slot and thus in all subsequent slots. Although the configured inputs
cannot be accessed, the CPU starts up.
Note that the user program cannot function correctly in this case and take the appropriate
measures.
10.6.2

STOP mode

Function
The CPU does not execute the user program in STOP mode.
All outputs are disabled or react according to the parameter settings for the particular I/O
module: They provide a substitute value as set in the parameters or retain the last value
output keeping the controlled process in a safe operating status.
10.6.3

RUN mode

Function
In "RUN" mode the cyclic, time-driven, and interrupt-driven program is executed. Addresses
that are in the "Automatic Update" process image are automatically updated in each program
cycle. See also the section Process images and process image partitions (Page 104).
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 is finished 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 and diagnostics interrupts can interrupt the cyclic
program flow and prolong the cycle time.
Distributed I/O system
System Manual, 12/2015, A5E03576849-AF
Commissioning
10.6 Operating modes of the CPU
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