Defective State - Siemens SIMATIC CPU 410 System Manual

System and operating states of the CPU 410
7.1 CPU 410 operating modes
4. If a multiple-bit error occurs on a CPU in redundant operation, that CPU will switch to
ERROR-SEARCH operating state. The other CPU becomes master, if necessary, and
continues running in solo operation.
But: OB 84 is called if 2 or more single-bit errors occur on a CPU in redundant operation
within 6 months. The CPU does not change to ERROR-SEARCH operating state.
5. If synchronization is lost during redundant operation, the standby CPU changes to
ERROR-SEARCH operating state. The other CPU remains master and continues running
in solo operation.
You can find additional information on the self-test in Self-test (Page 114).
7.1.7

DEFECTIVE state

If an error has occurred that cannot be automatically cleared by the operating system, the
CPU switches to the DEFECTIVE state and all LEDs flash.
The CPU switches to the DEFECTIVE state in the following cases:
● The user data is inconsistent.
● A reboot has already been carried out within the previous 24 hours.
● The event that led to the defect is preventing an automatic reboot.
CPU response following reboot
The CPU operating system tries to switch back to RUN by rebooting the CPU.
The CPU responds as follows to a reboot:
1. The CPU writes the cause of the error to the diagnostics buffer.
2. The CPU generates the current service data.
3. The CPU checks if a reboot is possible.
A reboot is not possible in the following cases:
– There is an inconsistency in the user data.
– A reboot has already been carried out within the previous 24 hours.
– The event that led to the defect is preventing an automatic reboot.
4. The CPU records the automatic reboot in the diagnostics buffers (event W#16#4309
"Memory reset launched automatically" or W#16#452B "CPU REBOOT for clearing data
inconsistency")
5. The CPU runs internal tests.
6. In a redundant system, the standby CPU links up to the master in operation.
7. In stand-alone operation and solo mode, the CPU load the backed up user program and
executes a warm restart
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CPU 410 Process Automation/CPU 410 SMART
System Manual, 05/2017, A5E31622160-AC