Rockwell Automation 440L GuardShield PAC Type 4 Safety Light Curtain - Manual (Page 9)

GuardShield™ PAC Safety Light Curtain Installation Instructions
7
Original instructions
The test input must be configured via a dip-switch located in the
GuardShield PAC transmitter.
Beam Coding
If several safety light curtains are operating in close proximity to
one another, it is possible that the transmitter’s infrared light from
one GuardShield PAC system is “seen” by another GuardShield
PAC system’s receiver. This would cause a “nuisance” stop. To
prevent this optical interference, the GuardShield PAC has the
ability to have the transmitter generate different beam patterns,
which is referred to as “Beam coding.” Selection and activation of
beam coding is accomplished through dip-switch settings in both
the transmitter and receiver.
The following settings are available in the GuardShield PAC safety
light curtain; noncoded and coded.
Applications and Application Require-
ments
Applications
The GuardShield PAC multi-beam safety light curtain may be used
as an opto-electronic fence; detecting the presence of personnel
as they pass through the sensing field or for safeguarding access
to a hazardous area or machine process. Used in combination
with corner mirrors, the GuardShield PAC multi-beam safety light
curtains provide multiple-side access detection.
When using corner mirrors to protect multiple sides of a machine
or work cell, the GuardShield PAC with integrated laser alignment
is the preferred solution. Activation of visible laser light allows
positioning and adjustment of the transmitter, receiver and
corner mirrors.
A typical system configuration for access detection to a hazardous
area or machine process is to have the GuardShield PAC multi-
beam safety light curtain connected to an external module along
with two or four sensors. The external module allows material to
pass through the GuardShield PAC multi-beam’s sensing field
without stopping the machine or equipment as long as the
muting conditions are met. As the material is moving through the
process, the GuardShield PAC multi-beam’s sensing field is
interrupted and the outputs switch to the OFF state. However, if
the muting module sensors are interrupted with the proper
timing, the module disregards the GuardShield PAC multi-beam’s
outputs and remains in the ON condition, allowing the machinery
or equipment to continue operation.
If the muting sensors are not interrupted and maintained in the
required timing and or sequence, the muting module will switch
OFF when the GuardShield PAC multi-beam’s sensing field is
interrupted.
IMPORTANT
Beam coding improves resistance to optical
interference.
Beam coding increases the system’s response
time, which may also increase the required
safety distance. Refer to Safety Distance
calculations on page 9 of this manual.
Figure 2 is an example of a GuardShield PAC three-beam safety
light curtain used as an opto-electronic fence with corner mirror
columns.
Figure 3 is an example of a GuardShield PAC three beam with four
retroreflective sensors and an external muting module.
Figure 2: GuardShield PAC three beam with corner mirror columns
Figure 3: GuardShield PAC three beam with muting module
Application Requirements
The protective functions of the PAC can only be used properly
when the following conditions are satisfied:
• The machine or installation must be controlled electrically.
• It must be possible to stop hazardous machine movement.
• The PAC must be installed so that entry into the danger
zone interrupts one or more of the light beams.
The light beam diameter of 23 mm (0.90 in.) must be fully
covered, to assure a change in state of outputs.
Release can only be achieved with the use of a restart switch.
The restart switch must be located such that it cannot be pressed
from inside the danger zone.
The GuardShield PAC should be mounted such that upon
interruption of the light beam, the dangerous location can only
be reached if the dangerous condition of the machine has been
stopped. The requirement for this is that there is a proper safety
GuardShield GuardShield
PAC
Transmitter
PAC
Receiver
Corner Mirror
Roller Work Path
Power
Supply
Work
Piece
Muting
Module
Work
Piece