Overview Of Sensors - Lenze 8400 StateLine C Hardware Manual

10 Safety engineering

Overview of sensors

10.3 Overview of sensors
Passive sensors
Passive sensors are two−channel switching elements with contacts. The connecting cables
and the sensor function must be monitored.
The contacts must switch simultaneously (equivalently). Nevertheless, safety functions
will be activated as soon as at least one channel is switched.
The switches must be wired according to the closed−circuit principle.
Examples of passive sensors:
Door contact switch
ƒ
Emergency−off control units
ƒ
Active sensors
Active sensors are units with two−channel semiconductor outputs (OSSD outputs).
Drive−based safety integrated in this device series allows for test pulses < 1 ms to monitor
the outputs and cables.
P/N−switching sensors switch the positive and negative cable or signal and earth cable of
a sensor signal.
The outputs must switch simultaneously. Nevertheless, safety functions will be activated
as soon as at least one channel is switched.
Examples of active sensors:
Lightgrid
ƒ
Laser scanner
ƒ
Control
ƒ
Sensor inputs
Deactivated sensors connected can give the impression of safety. This is why the
deactivation of sensors by mere parameter setting is not permissible and not possible.
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