Self-Test - Siemens SIMATIC CPU 410 System Manual

System and operating states of the CPU 410

7.3 Self-test

7.3 Self-test
Processing the self-test
The CPU executes the complete self-test program after an unbuffered POWER ON, e.g.,
POWER ON after initial insertion of the CPU or POWER ON without backup battery, and in
the ERROR-SEARCH operating state.
The duration of the self-test is approximately 7 minutes.
In a fault-tolerant system, if the CPU calls for a memory reset and a buffered Power Off/On is
then carried out, the CPU performs a self-test even though it was buffered.
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. This time interval is at least
90 minutes and can be extended in the configuration to reduce the impact of the self-test on
the runtime of the user program. However, it also extends the time interval in which a
possible error is detected.
Response to errors during the self-test
If the self-test returns an error, the following happens:
Table 7- 3
Type of error
Hardware fault
Hardware fault, which is signaled via
a one-sided OB 121 call
RAM/PIQ comparison error
Checksum errors
Multiple-bit errors
Hardware fault with one-sided OB 121 call
If a hardware fault occurs that triggers a one-sided OB 121 call and this fault occurs for the
first time since the last unbuffered POWER ON, the faulty CPU switches to ERROR
SEARCH operating state. The fault-tolerant system switches to stand-alone operation. The
cause of the error is written to the diagnostics buffer.
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Response to errors during the self-test
System response
The faulty CPU switches to DEFECTIVE state. Fault-tolerant
system switches to stand-alone operation.
The cause of the error is written to the diagnostics buffer.
The CPU with the one-sided OB 121 switches to ERROR-
SEARCH. Fault-tolerant system switches to stand-alone
operation (see below).
The cause of the error is written to the diagnostics buffer.
The configured system or operating state is assumed (see
below).
The response depends on the error situation (see below).
The faulty CPU switches to ERROR-SEARCH operating
state.
CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC