System Modes Of The S7-400H; Self-Test; Overview Of The S7-400H System Modes - Siemens SIMATIC S7-400H Manual

System and Operating Modes of the S7-400H

Self-Test

Malfunctions have to be detected, isolated and reported as quickly as possible.
Consequently, wide-ranging self-test functions have been implemented in the
S7-400H that run automatically and entirely in the background.
The following components and functions are tested:
• interconnection of the central controllers
• processor
• Memory
• I/O bus
If the self-test detects an error, the fault-tolerant system tries to eliminate it or to
suppress its effects.
5.2

System Modes of the S7-400H

The system modes of the S7-400H result from the operating modes of the two
CPUs. The term "system mode" is used to obtain a simplified expression which
identifies the concurrent operating modes of the two CPUs.
Example: Instead of "the master CPU is at RUN and the standby CPU is in the
LINK-UP mode" we use "the S7-400H is in the Link-Up system mode".
Overview of the system modes
The following table shows the system modes that are possible with the S7-400H.
Table 5-1
System Modes of the
S7-400H S7-400H
Stop
Startup
Single Mode
Linking
Update
Redundant mode
Hold
5-4

Overview of the S7-400H system modes

STOP
STARTUP
RUN
RUN
RUN
RUN
HOLD
Operating Modes of the Two CPUs
Master
STOP, deenergized, DEFECTIVE
STOP, deenergized,
DEFECTIVE, no synchronization
STOP, TROUBLESHOOTING,
deenergized, DEFECTIVE, no
synchronization
STARTUP, LINK-UP
UPDATE
RUN
STOP, deenergized, DEFECTIVE
Automation System S7-400H Fault-tolerant Systems
Standby
A5E00068197-07