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Function description
}
Outputs that are switched off are checked via regular on tests.
– On tests are run based on the configured repetition time. If a repetition time has not
– The maximum duration of the on test can be configured (default value: 3 ms)
– Outputs that are switched off are switched on for the duration of the on test.
– The load must not switch on because of the test.
Excluding individual outputs from the output test:
}
If a plant is particularly sensitive to the output test, the output test may be switched off for
individual outputs.
}
The test must be replaced by other measures, depending on the safety requirement.
}
When output tests are switched off:
– The correct switch state is always checked.
– The output's ability to switch will not be detected until the next time the output is
Monitoring the maximum permitted test cycle time
}
The duration of a test cycle depends on the number and type of modules. A maximum
test cycle time can be configured. If the output test is not run within the configured cycle
monitoring time, then an error is registered.
Testing for shorts
}
The outputs are switched on individually in order to detect shorts across contacts.
}
For applications in accordance with Category 4, PL e and SIL 3, detection of shorts
between contacts must be guaranteed either via the on/off test or through other meas-
ures (e.g. asynchronous switching). A short between contacts must be simulated during
commissioning.
Outputs
}
The head module sets the output status via the module bus.
}
The max. capacity at an output depends on the load (see characteristic). Connecting a
higher capacity may lead to an error.
}
Operation with electronic contactors has not been tested and may lead to errors. Please
contact our Customer Support team if you are using electronic contactors.
Operating Manual PSS u2 EF 8DO 0.5A
1003621-EN-03
been configured, then on tests are run in each test cycle.
switched on/off. That is why the outputs must be switched regularly during normal op-
eration, so that safety and characteristic safety values are not reduced.
WARNING!
When wiring an output with capacitance it is essential to note the pulse dur-
ation, repetition period and scan time of the power-up test, otherwise the
load may switch on unintentionally.
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