Siemens SIMATIC S7 F, Manual

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Fail-Safe Blocks
Fail-Safe Systems
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A5E00085588-03
8.15.1 Error Handling of Driver Blocks
The driver blocks can respond to the following errors:
•
Communication errors, such as
- TIMEOUT errors
The module has not received a new frame from the CPU or has not
responded to it within the configured monitoring time (TIMEOUT).
- Check value error (CRC):
The check sum of the transferred data doesn’t match the check sum
supplied.
- Watchdog error (incorrect consecutive number)
The module has not received the frame with the expected consecutive
number from the CPU or sent the expected response to the CPU with the
new consecutive number.
•
Discrepancy errors in the case of redundant digital input modules
•
Module faults reported by the F-I/Os.
•
Channel faults reported by the F-I/Os (ET 200M: only if the "Group Diagnosis"
parameter is set).
Error Reaction
•
F channel drivers for digital input modules output the substitute value 0 at the
outputs.
•
F channel drivers for analog input modules output at the outputs the substitute
value or the last valid value, depending on the parameterization.
•
F channel drivers for digital output modules output the substitute value 0 to the
module instead of the process values.
Note
The output of simulation values has priority over the output of substitute values in
the case of input modules.