Rockwell Automation Publication 450L-UM001F-EN-P - March 2022
21
Chapter
3
Operation
This chapter provides information on the special features and properties of the
450L safety light curtain. It also describes the structure and functions of the
unit, particularly the different operating modes.
Principle of Operation
A functional GuardShield™ safety light curtain system includes:
•
Two transceiver sticks (same model, length, and resolution)
•
A transmitter plug-in
•
A receiver plug-in
The type of plug-in defines which way a transceiver stick performs: As a
transmitter stick or as a receiver stick. The maximum distance between
transmitter and receiver sticks is referred to as the operating distance or
operating range (see
). The GuardShield systems also require a
minimum operating distance. If a system is installed below this distance, the
safety outputs do not switch to on. The maximum operating range is reduced
by using deflector mirrors and/or weld shields.
The protective field height of a GuardShield safety light curtain is equal to the
total length of the stick.
Figure 9 - Principle Operation of a 450L Safety Light Curtain System
A short time after the power-up and alignment of a system, nonvisible infrared
light beams build up a plane of detection (protective field) between the two
sticks. The axis of the detection zone is vertical to the front window of the light
curtain sticks.
Sequential pulses of infrared light are sent between the two sticks. The beam
status analysis and the processing are done by the receiver. When one or more
beams are interrupted, the two output signal switching devices (OSSDs) turn
off. A safety control, safety relay, or safety contactor evaluates the signal to
stop the dangerous state of the machine.
Detection Zone
Operating Distance
Receiver Stick
Protective Field Height
Connection Plugs of
Inserted Plug-ins
Connection Plugs of
Inserted Plug-ins
Transceiver Stick
