H Parameters - Siemens SIMATIC PCS 7 Operating Manual

Configuring S7F/FH hardware
6.1 Adapting CPU parameters (single F-system)
6.1.5

H parameters

Self-test (advanced CPU test)
The CPU tests the following during the self-test:
● Processor
● Internal memory
● I/O bus
If the test detects any faults, they are reported and the CPU goes to STOP.
Test cycle time
The test cycle time (default setting: 90 minutes) indicates the time taken for a complete
background self-test.
Note
For S7 F/FH systems, this parameter can be increased up to a maximum of 12 hours (720
minutes).
In S7 F/FH systems, the test may not be modified by calling SFC 90, "H_CTRL".
Otherwise, the safety program will go to F-STOP after a maximum of 24 hours. Switching
test components on or off is prohibited.
In the event of a STOP, the self-test enters the following diagnostics event in the diagnostic
buffer of the F CPU: "Safety program: Error detected" (event ID 16#75E1).
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Compendium Part B - Process Safety (V8.2)
Operating Manual, 07/2016, A5E35031794-AB