Siemens SIMATIC ET 200SP F-AI 4xI 0(4) 20mA 2-/4-wire HF Series Manual page 33

Analog input module

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Example

The following diagrams show you the behavior of the discrepancy evaluation when standard

value = MAX.

The upper of the two diagrams shows you the characteristic curve of the two process values.

The dashed line represents the absolute tolerance range configured in this example.

The lower of the two diagrams shows you the standard value signaled to the F-CPU.

In this example, on the first occurrence of a discrepancy, process value 1 is within the

tolerance range again before expiration of the discrepancy time. This means the discrepancy

error is not signaled.

In this example, on the second occurrence of a discrepancy, process value 1 is outside the

tolerance range when the discrepancy time expires. As a result, a discrepancy error is

signaled with 7FFF

of the discrepancy time. In the PII, the substitute value 0 is set for the safety program.

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