Startup Mode - Siemens SIMATIC PCS 7 CPU 410-5H System Manual

Operator controls and operating modes of the CPU 410-5H
7.1 Operating modes of the CPU 410-5H
7.1.3

STARTUP mode

Startup types
The CPU 410 distinguishes between two startup types: cold restart and warm restart.
Cold restart
● During a cold restart, all data (process image, bit memory, timers, counters and data
blocks) is reset to the start values stored in the program (load memory), regardless of
whether they were configured as retentive or non-retentive.
● The associated startup OB is OB 102
● Program execution is restarted from the beginning (OB 102 or OB 1).
Warm restart
● A warm restart resets the process image and the bit memories, timers, and counters.
All data blocks assigned the "Non Retain" attribute are reset to the downloaded values.
The other data blocks retain their last valid value.
● The associated startup OB is OB 100
● Program execution is restarted from the beginning (OB 100 or OB 1).
● If the power supply is interrupted, the warm restart function is only available in backup
mode.
Special features in redundant mode
The special features described below apply to startup when you operate two CPUs 410
redundantly.
Startup processing by the master CPU
The startup system state is always processed by the master CPU in redundant mode.
During STARTUP, the master CPU compares the existing I/O configuration with the
hardware configuration that you created in STEP 7. Startup of the system in case of a
difference is only possible if "Startup permitted with set-actual
difference" was configured.
The master CPU checks and assigns parameters for the following:
● the switched I/O devices
● the one-sided I/O including CPs and FMs assigned to it
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CPU 410-5H Process Automation
System Manual, 09/2014, A5E31622160-AB