Siemens SIMATIC CPU 410 System Manual page 115

RAM/PIQ comparison error
If the self-test detects a RAM/PIQ comparison error, the fault-tolerant system exits redundant
operating state and the standby CPU switches to ERROR SEARCH operating state (default
setting). The cause of the error is written to the diagnostics buffer.
The response to a recurring RAM/PIQ comparison error depends on whether the error recurs
in the first self-test cycle after troubleshooting or not until later.
Table 7- 4
Comparison error recurs ...
in the first self-test cycle after troubleshooting
after two or more self-test cycles after trouble-
shooting
Checksum errors
When a checksum error occurs for the first time since the last POWER ON without battery
backup, the system reacts as follows:
Table 7- 5
Time of detection
During the startup test after
POWER ON
In the cyclic self-test
(STOP or solo operation)
In the cyclic self-test
(redundant system state)
In the
ERROR-SEARCH operating
state
The cause of the error is written to the diagnostics buffer.
In an F-system, the F-program is already signaled at the first occurrence of a checksum error
in STOP operating state or in stand-alone operation that the self-test has detected an error.
CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC
Response to a recurring comparison error
Reaction to checksum errors
System response
The faulty CPU switches to DEFECTIVE state.
Fault-tolerant system remains in stand-alone operation.
The error is corrected. The CPU remains in STOP operating state or
in solo operation.
The error is corrected. The faulty CPU switches to ERROR-SEARCH
operating state.
Fault-tolerant system switches to stand-alone operation.
The faulty CPU switches to DEFECTIVE state.
System and operating states of the CPU 410
Reaction
Fault-tolerant system switches to stand-alone
operation.
Standby CPU switches to ERROR SEARCH and
then remains in STOP.
Fault-tolerant system switches to stand-alone
operation.
Standby CPU switches to ERROR SEARCH.
7.3 Self-test
115