Model CA
Cascading Safety Light Curtain
Product Overview
The Ultimate in Safety - Quality -
Value - Flexibility
Cascading
safety light curtains provide the user the ability to
connect additional sets of light curtains by daisy
chaining multiple emitters and receivers together. The
interconnecting cables are factory supplied and the user
defines length. The cascading of safety light curtains
provides mulitple areas of guarding in any plane (X, Y,
Z), while utilizing the control reliable dual safety
outputs from the Category 4 safety device for the safety
outputs to the machine control. The ability to guard
multiple areas on irregular shaped machines by cascading
safety light curtains reduces wiring and provides a lower
cost yet effective machine guarding
solution.
The Model CA
Cascading Safety Light Curtain is an infrared safety
light curtain that is designed to the IEC 61496 standard.
When properly installed, it protects the machine operator
by passing an invisible infrared light beam across an
area to be guarded and examining whether or not the light
beam(s) are blocked. If the light beam(s) are blocked,
monitored solid state outputs will open, issuing a “STOP”
command to the machines normally closed (N.C.) “STOP”
circuit. The CA System is composed of transmitting units
(EMITTERS), and receiving unit (RECEIVERS). The entire
system is control reliable Category 4 (per IEC 61496). A
single fault anywhere within the Model CA will not
prevent at least one of the solid state outputs from
opening up, (allowing a “STOP” command) when either a
beam is broken or an internal fault
occurs.
Theory of
operation.
The Model CA
Cascading Safety Light Curtain protects an area by projecting a
curtain of infrared light. The infrared emitters and receivers
face each other across the field to be protected. Each LED pair
is spaced along the length of the pylons at regular intervals
from .5" (12mm), up to 8" (203mm) depending on the application.
The smaller spacing are for finger guarding, the larger spacing
are for body protection. The emitter/receiver pairs are scanned
sequentially (one at a time) by a very short pulse of infrared
light starting from bottom (cable end), and working up to the
end, until every beam pair has been scanned. Two 16 bit
computers in the first emitter pylon and two 16 bit computers
in the first receiver pylon control the operation, as well as
cross check each pylon.
The
System.
The Model CA
Cascading Safety Light Curtain employs infrared technology in a
small sealed NEMA 4 (IP 67) aluminum housing with an infrared
passing (daylight filtering) acrylic lens. This system provides
harmless invisible protection and an unobstructed view of the
guarded area. There are two parts to the Model CA: An Emitter
pylon and a Receiver pylon. The Emitter pylon has no outputs.
The Receiver pylon contains two monitored solid state 24vdc
outputs. Both pylon sets are synchronized to each other
electronically as they are connected together with the
interconnect cables to the top and bottom of the next set of
pylons.
System
Safety.
The Model CA Cascading Safety
Light Curtain incorporates redundant, and diverse technology
that provides a backup for every system that could cause an
unsafe condition.
External
Device Monitoring
(EDM).
A method in which the Model CA Category
4 cascading safety light curtain logic monitors the state
of various external control devices. The control devices
are external and not part of the Model CAlight curtain
pylons. A lockout or stop signal will result if an unsafe
state is detected in an external device. The External
Device Monitoring (EDM) is an optional function of the
Model CA safety light curtain for monitoring the status
of external devices such as gate and door switches,
safety switches or the main control element of the drive
(MPCE). Solid state outputs are turned on separately to
be checked and to assure neither output has been shorted,
before fully turning on.
Design
Criteria.
Designed to meet IEC 61496-1
& 2, UL 1998, UL subject 491, OSHA, ANSI, CSA, ANSI-RIA
R15.06-1999
Microprocessor redundancy for
both Emitter and Receiver pylons
Redundant, monitored, 24vdc solid
state outputs (PNP)
Watchdogs on CPU’s and outputs
prevent unintentional output during lockups.
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