About Sensors
KVAL 994-X Operation Manual
4-34
About Sensors
The
Photo Electronic Detector
uses light as a trigger.
•
Photo Eye Detectors
contain both an emitter and receiver. If an
object is within the photo eye’s sensing field, light from the emitter
is reflected from the object back to the receiver. With
no object
is
in front of the photo eye, a constant 24VDC is sent to the PLC. If
an object is sensed by the photo eye, 0VDC is sent to the PLC.
• As a result, any of the photo detectors output equals 0VDC when a
door is sensed.
• Some detectors have an emitter and receiver built in one unit, such
as an in-feed sensor where a door blocks the light and reflects back
to the unit.
• Some detectors have an emitter and receiver built in separate units, such as the
through beam sensor set at a distance from each other. If an assembly is in between
the two sensors the machine will not operate.
One Package
The
Proximity Sensor
detects metallic objects without touching them.
• An inductive proximity sensor consists of a coil and ferrite core
arrangement, an oscillator and detector circuit, and a solid-state
output. The ferrite core and oscillator create a field generating out
the front of the sensor. When a metal object enters the field, a loss
in amplitude occurs. The detector circuit recognizes the loss of
amplitude and generates 0VDC to send to the PLC. When the metal object leaves
the sensing area, the sensor returns to 24VDC and sends it to the PLC.
• As a result, if a metal object is sensed, the output of the sensor equals 0VDC
Retract and
Extend Sensors
on a Cylinder
The L
imit Switch
is activated by an assembly moving a switch arm.
• Depending on the model of limit switch, the amount
of pre-travel (amount of movement from the arms
resting position) is either 5 or 20 degrees before the
limit switch actuates (Clicks).
Switch Arm
Summary of Contents for 994-X
Page 4: ...KVAL 994 X Operation Manual ...
Page 82: ...Calibration of the Back Section KVAL 994 X Operation Manual 3 22 ...
Page 124: ...KVAL 994 X Operation Manual 4 42 ...
Page 128: ...Index Kval 994 X ...
Page 129: ......