Lab 7 Sensors.pdf

What is a Sensors ?
A sensor is a device that measures a physical quantity and
converts it into a signal which can be read by an observer or by an
instrument.
A sensor is a device which receives and responds to a signal and
converts the signal into an electrical form which can be used by
electronic devices.
A sensor differs from a transducer in the way that a transducer
converts one form of energy into other form whereas a sensor
converts the received signal into electrical form only.
http://en.wikipedia.org/wiki/Sensor

Importance of Sensors
Without sensors most electronic applications
would not exist. They perform a vital function,
namely providing an interface to the real
world. The importance of sensors requires an
understanding of the types available and how
to use them for a particular application.
Today's smart sensors, wireless sensors, and
micro technologies are revolutionizing sensor
design and applications.
http://www.isa.org/Template.cfm?Section=Books3&template=/Ecommerce/ProductDisplay.cfm&ProductID=7945

Categories of Sensors
Acceleration, Shock and Vibration Sensors
Biosensors
Chemical Sensors
Capacitive and Inductive Displacement Sensors
Electromagnetism in Sensing
Flow and Level Sensors
Force, Load and Weight Sensors
Humidity Sensors
Machinery Vibration Monitoring Sensors
Optical and Radiation Sensors
Position and Motion Sensors
Pressure Sensors
Sensors for Mechanical Shock
Temperature Sensors
Strain Gages
Nanotechnology-Enabled Sensors
Wireless Sensor Networks
Within each
category there
are many types
of sensors

Sensor Applications
Browse Products by Application:
Bar Code Reading
Color Mark and Registration Detection
Clear or Reflective Object Detection
Counting
Detection
Inspection
Labeling
Level Monitoring
Loop Control
Measurement
Metal Stamping
Temperature Monitoring
Web Monitoring
Wireless
Vehicle Detection
http://www.bannerengineering.com/en-US/products
Browse Products by
Industry:
Agriculture
Automotive
Car Wash
Food & Beverage
Material Handling
Packaging
Pharmaceutical &
Medical
Semiconductor

Most Common Sensors for
Detection , Positioning, and Counting
http://info.bannersalesforce.com/xpedio/groups/public/documents/literature/142025.pdf
Limit Switches Photo Sensors
Proximity Sensors Ultrasonic Sensors

Banner is #1 in Sensors
http://www.bannerengineering.com/en-US/products
For 20 consecutive years, Banner
Engineering has placed first in more than
50 independent studies of the purchasing
preference of engineers.
With more than 22,000 different products
across 40 industries, Banner offers you
the industry's most complete, integrated
and advanced line of photo eyes, sensors,
wireless sensors, vision sensors, vision
lighting, machine safety, and indicator
lights. Choose the worldwide leader.
Banner is preferred nearly four to one over
the closest competitor

Ultrasonic Sensors
Inverted Clear Object
Detection
Bottle Detection
Liquid Level Monitoring
http://info.bannersalesforce.com/xpedio/groups/public/documents/literature/142025.pdf
Ultrasonic sensors solve applications that photo electrics can’t. Ultrasonic
sensors are versatile, accurate and an effective solution for the toughest
applications challenges. Ultrasonic sensors use sound waves, not light, and
this makes them ideal for problematic clear material sensing applications.
Use ultrasonics to effectively and accurately sense liquids, clear objects
and targets in dirty environments. Ultrasonics are inherently impervious to
color differences, high reflectivity and glare, all of which are application
challenges for photoelectrics.

More Sensors
Temperature Switches
Pressure Sensor
4-20 ma output
Float Switches
Magnetic Reed Switches
Pressure Switches
Vibration Sensor

Chapter
Lab 7
Proximity Sensors
Programmable Logic Controllers

Inductive Proximity Sensors
If your target is metal, and if the sensing range isn't too great, you may
consider an inductive metal proximity sensor. An inductive metal proximity
sensor can ignore build-up of contaminants on its sensing face, unless the
build-up contains metal. Proximity sensors allow non-contact detection of
objects. They are used in many industries, including manufacturing,
robotics, semiconductor, etc. Inductive sensors detect metallic objects
while capacitive sensors detect all other materials.
http://http://www.automationdirect.com/adc/Overview/Catalog/
These sensors are available in 2-wire
AC, 2-wire AC/DC, and 2-3- or 4-wire DC
styles with 6.5, 8, 12, 18 and 30mm
diameters.

Inductive Proximity Sensors
Inductive Proximity Sensors detect
magnetic loss due to eddy currents that are
generated on a conductive surface by an
external magnetic field. An AC magnetic
field is generated on the detection coil, and
changes in the impedance due to eddy
currents generated on a metallic object are
detected.
http://www.ia.omron.com/support/guide/48/principles.html
Detection Principle of Inductive Proximity Sensors
Other methods include Aluminum-detecting Sensors, which detect the phase
component of the frequency, and All-metal Sensors, which use a working coil
to detect only the changed component of the impedance. There are also
Pulse-response Sensors, which generate an eddy current in pulses and detect
the time change in the eddy current with the voltage induced in the coil.

Capacitive Proximity Sensors
http://www.ia.omron.com/
Capacitive Proximity Sensors detect both metallic
and nonmetallic objects (water, plastic, etc.)
Capacitive Proximity Sensors detect changes in the
capacitance between the sensing object and the
Sensor. The amount of capacitance varies depending
on the size and distance of the sensing object.
An ordinary Capacitive Proximity Sensor is similar to
a capacitor with two parallel plates, where the
capacity of the two plates is detected. One of the
plates is the object being measured (with an
imaginary ground), and the other is the Sensor's
sensing surface. The changes in the capacity
generated between these two poles are detected.
Detection Principle of Capacitive Proximity Sensors

Proximity Sensors – Block Diagram
L1 L2
TRIAC
GATE
ANODE 1
ANODE 2
POWER
SUPPLY
TRANSFORMER
120VAC
BUFFER
LOAD
RECTIFIER
OSCILLATOR
TANK CIRCUIT
Inductive
Capacitive
OSCILLATOR
1. Tank circuit is tuned to resonance Xl = Xc and oscillates.
2. Metal object changes inductance in tank circuit, detuning the tank circuit and oscillations stop.
3. Oscillator no longer produces sign wave to be rectified.
4. Rectifier has no D.C. to produce with no sign wave input.
5. Amplifier is also an inverter, and with a o input, it produces an output to biase the gate of the Triac
6. Traic is turned on with bias voltage on the gate and it conducts AC through it.
7. Load now has power applied to operate.

Chapter
Lab 7
Photo Sensors

Photo Sensors
Photoelectric Sensors:
A photoelectric sensor is an optical
control that detects a visible or invisible
beam of light, and responds to a
change in the received light intensity
Light Sources:
A sensor's light source is called its emitter. Most
Banner photoelectric sensors use light emitting
diodes (LEDs) for the emitter light source.
Another light source used in Banner sensors is the
laser, which provides a narrow, intense beam to
increase the sensor’s range.
http://www.bannerengineering.com

Photo Sensor Applications
Sensors are used to:
Sense baking goods on a conveyor
Apply tamper proof seals
Inspect and control fill levels
Separate clear bags
Sense boxes on a conveyor
Conduct error proofing in assembly
processes
More Applications: Links
Bar Code Reading
Color Mark and Registration
Detection
Clear or Reflective Object
Detection
Counting
Detection
Inspection
Labeling
Level Monitoring
Loop Control
Measurement
Metal Stamping
Temperature Monitoring
Web Monitoring
Wireless
Vehicle Detection

3 Categories of Photo Sensors
Self-contained, which contain the
optical and electrical components of a
sensor system.
Remote, where the optical and
electrical components are separated.
Fiber Optics, which only pipe the light
beam into and out of the sensing
location.

Self Contained:
A self-contained photoelectric
sensor contains the optics,
along with the electronics.
It requires only a power
source.
The sensor performs its own
modulation, demodulation,
amplification, and output
switching.

Remote:
Remote photoelectric sensors
contain only the optical components
of a sensor.
The circuitry for power input,
amplification, and output switching
are located elsewhere, typically in a
control panel.
This allows the sensor, itself, to be
very small. Also, the controls for the
sensor are more accessible, since
they may be bigger.

Fiber optics:
When space is restricted or the
environment too hostile even for
remote sensors, fiber optics may
be used.
Fiber optics are passive
mechanical sensing components.
They may be used with either
remote or self-contained sensors.
They have no electrical circuitry
and no moving parts, and can
safely pipe light into and out of
hostile environments.

Photo Sensors – Sensing Modes
http://www.bannerengineering.com/training/subtopic.php?topicID=A1_00
Sensing mode is one of the most important criteria when
selecting a photo sensor. The best sensing mode for your
application will be a reliably detection of your object without
being confused by factors in the environment.
There are 6 sensing modes
What are the pros and cons
of each mode ?
Which sensing mode suits
an application ?
Banner Tutorials
Opposed (11 pages)
Retroreflective (13 pages)
Diffuse (13 pages)
Divergent (10 pages)
Convergent (11 pages)
Background Suppression (13 pages)

1. Opposed Mode:
An opposed-mode sensor will have a separate
emitter and receiver pair. The emitter sends the
light beam to the receiver, which is positioned
opposite the emitter.
For an object to be detected, it must pass
between the two, and interrupt or "break" the
beam of light.
Opposed-mode sensing is highly reliable,
provides a high amount emitted energy, is
impervious to surface reflectivity, and is
excellent for parts counting.
However, opposed-mode sensing may not be
the best solution for sensing clear materials.

http://www.bannerengineering.com/training/subtopic.php?topicID=A1_02_010
2. Retroreflective Mode:
A retroreflective sensor contains both the emitter
and receiver element.
The effective beam is established when the
emitter sends a light beam which is bounced off a
retroreflector, back to the emitter. An object is
detected when it breaks this effective beam.
Retroreflective-mode sensors offer reliability, and
are convenient in applications where sensors can
be mounted only on one side of a process.
However, retroreflective sensors can lose gain
twice as fast as opposed mode sensors, and they
aren't always the best choice for sensing shiny,
clear, or very small objects.

http://www.bannerengineering.com/training/subtopic.php?topicID=A1_03_010
3. Diffuse-mode
In diffuse-mode sensors, the emitter and receiver
are housed in the same sensor, like in the
retroreflective mode.
However, the effective beam is made when the
target object bounces the light beam back from
the sensor's emitter to the receiver.
Diffuse-mode sensors are very convenient and
are often used when opposed or retroreflective-
mode sensors aren't practical.
Diffuse-mode sensors are significantly affected
by the reflectivity of the target object(s). These
sensors also tend to lose their excess gain
quickly. Diffuse-mode sensors should not be
used in applications where small parts need to be
detected, in parts counting applications, or where
a reflective background is close to the object to
be sensed.

4. Divergent-mode
Like diffuse-mode sensors, divergent-mode
sensors detect an object when that object
bounces light back from the sensor's emitter to
the receiver. However in the divergent mode, the
sensor casts a much wider angle of light.
Divergent-mode sensors are excellent in
applications which involve detection of clear
materials, small objects, shiny surfaces, and
where background rejection is necessary.
By design, divergent-mode sensors make
inefficient use of sensing light energy, and offer
only low levels of excess gain. Also, they have a
very wide field of view, and caution should be
used in applications where an object on the side
of the sensor may be detected.

5. Convergent mode:
The convergent mode makes very efficient
use of reflective energy. It uses a lens to
focus its beam to an exact point, which
produces a small, intense and well-defined
sensing area at a fixed distance in front on
the sensor.
Convergent-mode sensors are excellent in
applications involving accurate
positioning, counting radiused objects, and
color sensing.
Reconsider the use of convergent sensors
when the object to be detected passes by
at unpredictable distances, or if the object
is very shiny.

6. Background suppression:
Background suppression sensors such as
adjustable-field and fixed-field mode have
a definite limit to their sensing range, and
are able to ignore objects beyond that
range.
These sensors are especially good in
applications where highly-reflective
backgrounds need to be ignored, to
accurately detect height differentials, and
for low contrast applications.
With background suppression sensors,
shiny background objects can affect how
light is reflected back to the sensor.
Additionally, if the object to be detected is
not properly oriented to the sensor, you
could get a false output.

Photo Sensors - Aligning the Beam.
Source
-24 vdc Grd.
Relay
+24vdc
LED
While observing the light
(LED) on the sensor, move the
reflector vertically and
horizontally to determine the
center of the reflector.
The reflector then must be
aligned properly and mounted
secure.
Block the beam temporally to
see if the load is energized
and de-energized.

Photo Sensors - Dark & Light Operate
Light Operate
Dark Operate
Source
-24 vdc Grd.
Relay
+24vdc
When the beam is broken there is no
light back to the receiver (dark) so
the sensor switches power
(operates) the load.
Source
-24 vdc Grd.
Relay
+24vdc
When the beam is clear and not
broken there is light back to the
receiver (light) so the sensor
switches power (operates) the load.

Photo Sensors - Sinking & Sourcing
Ground (-24 vdc) is
switched to the load
Power (+24 vdc) is
switched to the load
http://info.bannersalesforce.com/xpedio/groups/public/documents/literature/78466_26.pdf

Photo Sensors - Sinking & Sourcing (Relay)
Sinking a relay
Sourcing a relay
Source
-24 vdc Grd.
Relay
+24vdc
Sink
Relay
+24vdc -24 vdc Grd.
Sourcing:
When the beam is broken, The
sensor switches the source (+24vdc)
to the output lead. The relay is wired
from the sensor output to ground.
Sinking:
When the beam is broken, The sensor
switches the ground (-24vdc) to the
output lead. The relay is wired from the
sensor output to +24vdc.

Photo Sensors - Sinking & Sourcing (PLC)
Sinking to the PLC
Sourcing to the PLC
Source
-24 vdc Grd.
+24vdc
Resistor
PLC Input
Sink
+24vdc -24 vdc Grd.
Resistor PLC Input
Sinking:
switches the ground (-24vdc) to the output
lead. The pull down resistor is wired from
the sensor output to +24vdc to provide a
load for the sensor’s current flow.
Sourcing:
switches the source (+24vdc) to the
output lead. A pull up resistor is needed
to provide a load for current to flow
through the sensor to ground.

Photo Sensors – Block Diagram
1. Oscillator produces square wave pulses
2. Modulator turns inferred LED on at high frequency pulse rate
3. Light bounces off reflector to receiver (Photo Transistor)
4. Photo transistor picks up light pulses and sends out pulses to de-modulator
5. De-modulator is sensitive to only the pulse rate produced by oscillator. (rejecting light flashes & noise)
6. Demodulator turns on buffer amplifier to bias the gate of the triac on
7. Traic turns on conducting current to load to operate load device
CR1
L1
L2
TRIAC
GATE
ANODE 1
ANODE 2
POWER
SUPPLY
TRANSFORMER
24VAC
REFLECTOR
MODULATOR
INFERRED LIGHT
OSC.
I-R
PHOTO
TRANSISTOR
DE-
MODULATOR
BUFFER
AMP
BLACK
RED
WHITE

Chapter
Lab 7-1
Proximity Sensors Lab

Proximity Sensor used on PLC Trainer

Proximity Sensor used on PLC Trainer
Relay
+24 vdc
Ground
Omron E2E-X2D1-N Proximity Sensor wired to a Relay

Proximity Sensor Circuit on PLC Trainer
Ground
+24 vdc
4.7K ohm
To PLC input
Omron E2E-X2D1-N Proximity Sensor wired to a PLC
A load resistor is required to allow
current to flow through the prox.
I = E/R = 24 /4700 = .005 a or 5 ma

Chapter
Lab 7-2
Photo Sensors Lab

Photo Sensor - Used on PLC Trainer
Description:
Series 6000 photoelectric sensors provide reliable general purpose sensing in a
compact package.
The Transmitted Beam Light Source has a red power indicator.
Each sensor has a clutch-protected four-turn adjustment potentiometer.
The 20-132V AC/DC sensor offers a single 300mA Power MOSFET output.
Light operate or dark operate is selected by catalog number for all Series 6000
sensors.

Photo Sensors - Trainer Lab Circuit
Retroreflective Alignment:
Adjust the sensitivity to the maximum setting, by turning the sensitivity
potentiometer clockwise. Aim the sensor on the reflector until the
alignment indicator on the sensor turns On (light operate) or Off (dark
operate).
To be certain that the beam is centered, sweep the beam on the reflector
in the horizontal plane and determine the position the alignment indicator
turns On and then Off. Set the beam halfway between both positions. Do
the same in the vertical plane. Break the beam with the object to be
detected and check to see if the alignment indicator turns Off.
It may be necessary to reduce the sensitivity or change to a smaller sized
reflector to detect small, translucent or transparent objects. Restore the
beam by removing the object and check to see if the alignment indicator
turns On again. For shiny objects angle the sensor so that the beam is
not perpendicular to the object. For highly reflective materials use a
polarized retroreflective sensor.

Relay
Photo Sensor driving a relay direct.
The 42SRU-6005 Photo Sensor is a
Dark Operate with a SINK output. The
load is connected to ground when beam
is broken.

10K ohm
PLC Input
Photo Sensor wired to a PLC
requires a pull up resistor
The 42SRU-6005 Photo Sensor is a
Dark Operate with a SINK output. The
load is connected to ground when beam
is broken.

Allen-Bradley 42CM-UIMPB-D4 Photo Sensor
1 4
2 3
D.O.
D.O.
+ 24 VDC
- 24 VDC
Ground
Input: 10-30 VDC
Load 100 ma.
Output PNP (SINK Output)
Dark and Light Operate
(L.O and D. O.)
with Allen-Bradley 889D-F4AC-2 Photo Sensor Cable
White L.O.
Blue Ground
Black D.O.
Brown +24 vdc

Allen-Bradley 42CM-UIMPB-D4 Photo Sensor
Wired to PLC:
Photosensor wired for
Dark Operate with a SINK
output. The load is
connected to ground
when beam is broken.
Wired to a Relay:
Photosensor wired for
Dark Operate with a SINK
output. The load is
connected to ground
when beam is broken.

Lab 7 Sensors.pdf

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