Siemens SIMATIC S7-400H - Self-Test; Table 11- 3 Response to Errors During the Self-Test

System and operating states of the S7–400H
11.4 Self-test
S7-400H
System Manual, 03/2012, A5E00267695-11
137
11.4 Self-test
Processing the self-test
The CPU executes the complete self-test program after POWER ON without backup, e.g.
POWER ON after initial insertion of the CPU or POWER ON without backup battery, and in
the ERROR-SEARCH mode.
The self-test takes at least 10 minutes. The larger the load memory used (e.g. the size of the
inserted RAM memory card), the longer the self-test.
When the CPU of a fault-tolerant system requests a memory reset and is then shut down
with backup power, it performs a self-test even though it was backed up. A memory reset is
requested when you remove the memory card, for example.
In RUN the operating system splits the self-test routine into several small program sections
("test slices") which are processed in multiple successive cycles. The cyclic self-test is
organized to perform a single, complete pass in a certain time. The default time of 90
minutes can be modified in the configuration.
Response to errors during the self-test
If the self-test returns an error, the following happens:
Table 11- 3 Response to errors during the self-test
Type of error System response
Hardware fault without one-sided call
of OB 121
The faulty CPU enters the DEFECTIVE state. The fault-
tolerant system switches to standalone mode.
The cause of the error is written to the diagnostic buffer.
Hardware fault with one-sided call of
OB 121
The CPU with the one-sided OB 121 enters ERROR-
SEARCH mode. The fault-tolerant system switches to
standalone mode (see below).
RAM/POI comparison error The cause of the error is written to the diagnostic buffer.
The CPU enters the configured system or operating state
(see below).
Checksum errors The response depends on the error situation (see below).
Multiple-bit errors The faulty CPU enters ERROR-SEARCH mode.
Hardware fault with one-sided call of OB 121
If a hardware fault occurs with a one-sided OB 121 call for the first time since the previous
POWER ON without backup, the faulty CPU enters ERROR-SEARCH mode. The fault-
tolerant system switches to standalone mode. The cause of the error is written to the
diagnostic buffer.