Table 8-4 Reaction To A Recurring Comparison Error; Table 8-5 Reaction To Checksum Errors - Siemens SIMATIC S7-400H System Manual

System and operating states of the S7-400H
8.5 Self-test
RAM/PIO comparison error
If the self-test returns a RAM/PIO comparison error, the fault-tolerant system quits redundant
mode and the standby CPU enters the TROUBLESHOOTING state (in default configuration).
The cause of the error is written to the diagnostics buffer.
The reaction to a recurring RAM/PIO comparison error depends on whether the error occurs
in the subsequent self-test cycle after troubleshooting or not until later.
Table 8-4
Comparison error recurs ...
in the first self-test cycle after troubleshooting
after two or more self-test cycles after
troubleshooting
Checksum errors
When a checksum error occurs for the first time after the last POWER ON without backup,
the system reacts as follows:
Table 8-5
Time of detection
During the startup test after
POWER ON
In the cyclic self-test
(STOP or single mode)
In the cyclic self-test
(redundant system state)
In the TROUBLESHOOTING
state
Single-bit errors
The cause of the error is written to the diagnostics buffer.
In an F system, the F program is informed that the self-test has detected an error the first
time a checksum error occurs in STOP or single mode. The reaction of the F program to this
is described in the
90
Reaction to a recurring comparison error
Reaction to checksum errors
System reaction
The faulty CPU enters the DEFECTIVE state.
The fault-tolerant system switches to single mode.
The error is corrected. The CPU remains in STOP or in single mode.
The error is corrected. The faulty CPU enters the
TROUBLESHOOTING state.
The fault-tolerant system switches to single mode.
The faulty CPU enters the DEFECTIVE state.
The CPU calls OB 84 after the detection and elimination of the error.
S7-400F and S7-400FH Automation Systems
Reaction
The standby CPU first enters the
TROUBLESHOOTING state, and then goes into
STOP.
The fault-tolerant system switches to single mode.
Standby CPU enters the TROUBLESHOOTING
state.
The fault-tolerant system switches to single mode.
manual.
System Manual, 09/2007, A5E00267695-03
S7-400H