Function description
Operating Manual PSSu K F FAU B, PSSu K F FAU P
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Detection of shorts across contacts
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The test pulses are used to detect shorts between inputs. Shorts between inputs are de-
tected when the test pulses are different (test pulse T00, test pulse T01).
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Only the module's test pulses may be used to detect shorts.
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The module's test pulses may not be used to detect shorts between inputs on other mod-
ules.
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Shorts between inputs of the same module with the same test pulses will not be detected.
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Test pulses can be switched on or off.
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Test pulses are switched on in the default setting.
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When test pulses are switched off, the periphery supply is constantly available at the test
pulse outputs.
4.4
Outputs
4.4.1
Single-pole outputs
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2 single-pole digital outputs
Output test
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Outputs that are switched on are checked via regular off tests.
– Test pulses for outputs that are switched on: see
– Outputs that are switched on are switched off for the duration of the test pulse.
– The load must not switch off because of the test.
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Outputs that are switched off are checked via regular on tests.
– Test pulses for outputs that are switched off: see
– Outputs that are switched off are switched on for the duration of the test pulse.
– The load must not switch on because of the test.
Testing for shorts
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A test is regularly carried out to check for shorts between the outputs.
Excluding individual outputs from the output test:
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If a plant is particularly sensitive to the test pulses, the output test may be switched off for
individual outputs.
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The test must be replaced by other measures, depending on the safety requirement.
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When test pulses are switched off:
– The correct switch status is always checked.
– The output's ability to switch will not be detected until the next time the output is
switched on/off.
