Startup Mode - Siemens SIMATIC S7-400H System Manual

System and operating states of the S7–400H
11.3 The operating states of the CPUs
11.3.2

STARTUP mode

Except for the additions described below, the behavior of S7-400H CPUs in STARTUP mode
corresponds to that of standard S7-400 CPUs.
Startup modes
The fault-tolerant CPUs distinguish between cold restart and warm restart.
Fault-tolerant CPUs do not support warm restarts.
Startup processing by the master CPU
The startup system mode of an S7-400H is always processed by the master CPU.
During STARTUP, the master CPU compares the existing I/O configuration with the
hardware configuration that you created in STEP 7. If any differences are found, the master
CPU reacts in the same way as a standard S7-400 CPU.
The master CPU checks and parameterizes the following:
● the switched I/O devices
● its assigned one-sided I/O devices
Startup of the standby CPU
The standby CPU startup routine does not call an OB 100 or OB 102.
The standby CPU checks and parameterizes the following:
● its assigned one-sided I/O devices
Special features at startup
If the master CPU returns to STOP immediately after transition to RUN during startup of a
fault-tolerant system, the standby CPU takes over the master role and continues to start up.
In buffered PowerOn mode of a fault-tolerant system with large configurations, many CPs
and/or external DP masters, it may take up to 30 seconds until a requested restart is
executed. During this time, the LEDs on the CPU light up successively as follows:
1. All LEDs light up
2. The STOP LED flashes as it does during a memory reset
3. The RUN and STOP LEDs flash for about 2 seconds
4. The RUN LED flashes briefly 2 to 3 times
5. The STOP LED lights up for about 25 seconds
6. The RUN LED restarts flashing
Start up is about to begin.
Additional information
For detailed information on STARTUP mode, refer to the
132
Programming with STEP 7
System Manual, 03/2012, A5E00267695-11
manual.
S7-400H