Table 7- 6 Hardware Fault With One-Sided Call Of Ob 121, Checksum Error, Second Occurrence - Siemens SIMATIC PCS 7 System Manual

Operator controls and operating modes of the CPU 410-5H
7.3 Self-test
Hardware fault with one-sided call of OB 121, checksum error, second occurrence
A CPU 410–5H reacts to a second occurrence of a hardware fault with a one-sided call of
OB 121 and to checksum errors as set out in the table below, based on the various operating
modes of the CPU 410.
Table 7- 6 Hardware fault with one-sided call of OB 121, checksum error, second occurrence
Error
Hardware fault with one-
sided call of OB 121
Checksum errors
If a second checksum error occurs in solo or stand-alone operation after twice the test cycle
time has expired, the CPU reacts as it did on the first occurrence of the error. If a second
error (hardware fault with one-sided call of OB 121, checksum error) occurs in redundant
operation when troubleshooting is finished, the CPU reacts as it did on the first occurrence of
the error.
Multiple-bit errors
If a multiple-bit error is detected during redundant operation of a fault-tolerant system, the
CPU switches to ERROR-SEARCH operating state. When troubleshooting is finished, the
CPU can be linked up and updated again, and resume redundant operation. If there is no
error in the CPU, it switches to RUN and becomes master. The cause of the error is signaled
by the call of OB 84.
There are some rare cases in which multiple-bit and single-bit errors can occur due to very
challenging ambient conditions. If they occur only once, they do not interfere with the
hardware. If bit errors occur frequently, however, replace the hardware.
Single-bit errors
Single-bit errors are also detected and eliminated outside the self-test. The CPU calls OB 84
after elimination of the error.
Influencing the cyclic self-test
SFC 90 "H_CTRL" allows you to influence the scope and execution of the cyclic self-test. For
example, you can remove various test components from the overall test and re-introduce
them. In addition, you can explicitly call and process specific test components.
112
CPU in stand-alone operation/single mode
OB 121 is executed
The CPU enters the DEFECTIVE state if two
errors occur within two successive test cycles
(configure the length of the test cycle in HW
Config).
CPU in redundant operation
The faulty CPU switches to ERROR-SEARCH
operating state. The fault-tolerant system
switches to single mode.
The CPU enters the DEFECTIVE state if a
second error triggered by the first error event
occurs in ERROR-SEARCH mode.
CPU 410-5H Process Automation/CPU 410 SMART
System Manual, 09/2014, A5E32631667-AB