Pilz PSSu E F 4DI - Manual (Page 12)

Function description
Operating Manual PSSu E F 4DI(­T)(­R)
21310­EN­05 12
4 Function description
4.1 Module features
4.1.1 Functions
Module supply
} The module supply provides the module with voltage.
Periphery supply
} The module switches the periphery supply from the module bus to the base module ter­
minals.
} The periphery supply is used to supply or provide test pulses to the input devices.
Inputs
} The input status is signalled to the head module via the module bus.
} Test pulses can be used to check the inputs for shorts across contacts and correct
functionality.
} The inputs have input filters.
Test pulse outputs
} 2 test pulse outputs that use different test pulses (test pulse 0, test pulse 1)
} Short circuit­proof
} Current limitation
} Test pulses can be switched on or off.
} Test pulses are switched off in the default setting.
} When test pulses are switched off, the periphery supply is constantly available at the
outputs.
Detection of shorts across contacts
} The test pulses are used to detect shorts between inputs. Shorts between inputs are
detected when
} the test pulses are different (test pulse 0, test pulse 1) or when
– the test pulses originate from other modules on a PSSu system.
} Shorts between inputs of the same module with the same test pulses will not be detec­
ted.
Signal detection at the inputs
} A signal (“0” signal or “1” signal) is always ignored if it is present for less than the min­
imum processing time (see Technical details).
} A signal is always detected and transmitted to the process image (PII) if it is present for
longer than the maximum processing time plus the scan time of the module bus (t
2
+ t
3
,
see diagram and Technical details).