Processing Self-Tests; Response To Errors During The Self-Test; Hardware Fault With One-Way Ob 121 Call - Siemens SIMATIC S7-400H Manual

5.4 Self-Test

Processing self-tests

Following unbuffered POWER ON (e.g. POWER ON after plugging in the CPU for
the first time or POWER ON without a back-up battery) and in
TROUBLESHOOTING mode, the CPU executes the complete self-test program.
The processing time of the full self-test depends on the configuration of the
S7-400H and lasts approximately 90 to 220 sec.
At RUN the operating system divides the self-test into small program sections (test
slices) that are processed consecutively over a whole number of cycles. The cyclic
self-test is organized so that it runs once to the end within a certain time. The
default time is 90 minutes and can be changed in the configuration.

Response to errors during the self-test

If an error is detected as a result of the self-test, the following happens:
Table 5-4
Hardware fault (without one-way
OB 121 call)
Hardware fault with one-way
OB 121 call
RAM/PIQ comparison error
Checksum error

Hardware fault with one-way OB 121 call

If a hardware fault occurs with a one-way OB 121 call for the first time since the
previous unbuffered POWER ON, the faulty CPU goes into TROUBLESHOOTING
mode. The fault-tolerant system goes into single mode The cause of the error is
entered in the diagnostics buffer.
If a hardware fault occurs with a one-way OB 121 call again within seven days, the
faulty CPU goes into DEFECTIVE mode. The fault-tolerant system goes into single
mode
Automation System S7-400H Fault-tolerant Systems
A5E00068197-07
Response to errors during the self-test
Type of Error
System and Operating Modes of the S7-400H
System Response
Faulty CPU goes into DEFECTIVE mode. The
fault-tolerant system goes into single mode.
The cause of the error is entered in the diagnostics
buffer.
The CPU with the one-way OB 121 goes into
TROUBLESHOOTING mode. The fault-tolerant system
goes into single mode (see below).
The cause of the error is entered in the diagnostics
buffer.
The configured system or operating mode is assumed
(see below).
The response depends on the situation in which the
error was detected (see below).
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