Ram/Paa Comparison Error; Response To A Recurring Comparison Error; Checksum Errors; Response To Checksum Errors - Siemens SIMATIC S7-400H Manual

System and Operating Modes of the S7-400H

RAM/PAA comparison error

If the self-test detects a RAM/PIQ comparison error, the fault-tolerant system quits
redundant mode and the standby CPU goes into TROUBLESHOOTING mode
(default configuration). The cause of the error is entered in the diagnostics buffer.
The response to a recurring RAM/PIQ comparison error depends on whether the
error occurs in the subsequent self-test cycle or not until later.
Table 5-5
Comparison Error Occurs Again ...
In the first self-test cycle subsequent to error
search
After two or more self-test cycles
subsequent to error search

Checksum errors

If a checksum error occurs for the first time since the last unbuffered POWER ON,
the system responds as follows:
Table 5-6
Detection Time
During the power-up test after
POWER ON
In the cyclic self-test
(STOP or single mode)
In the cyclic self-test
(redundant system mode)
In TROUBLESHOOTING mode
The cause of the error is entered in the diagnostics buffer.
If a checksum error reoccurs within 7 days, the faulty CPU goes into DEFECTIVE
mode and the fault-tolerant system goes into single mode.
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 manual Automation Systems S7-400F and
S7-400FH.
5-12

Response to a recurring comparison error

Response to checksum errors

Faulty CPU goes into DEFECTIVE mode.
The fault-tolerant system goes into single mode.
The error is corrected. The CPU remains in STOP or in
single mode.
The error is corrected. Faulty CPU goes into
TROUBLESHOOTING mode.
The fault-tolerant system goes into single mode.
Faulty CPU goes into DEFECTIVE mode.
The fault-tolerant system goes into single mode.
Reaction
The standby CPU goes into
TROUBLESHOOTING mode and then into
STOP mode.
The fault-tolerant system goes into single
mode.
Standby CPU goes into
TROUBLESHOOTING.
The fault-tolerant system goes into single
mode.
System Response
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07