Download Encoder Basics

:
Encoders – Basic Training
Mandee Liberty & Vikram Phadke
National Encoder Product Specialists
Typical Industrial System
Input
Operation
(Application)
Controller
Output
Feedback
Sensor
: SICK, Inc.
: Confidential
2
Encoders within a Control System
Feedback
Sensor
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: Confidential
3
Encoder Definitions
What is an encoder?
:
An encoder is a device which converts a mechanical information of a shaft or
position into an electrical signal
Encoder
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4
Encoder Definitions
How is this accomplished?
:
As the code disc rotates, it shutters light from the LED and is received and
transmitted as square\sine waveforms
Receiver / Sensor
Code disc
Lens
Transmitter / LED
Shaft
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: Confidential
5
Encoder Selection Process
Type (Rotary, Linear, Incremental, Absolute)
Electrical Interface
Mechanical Considerations
: SICK, Inc.
: Confidential
6
Encoder Selection Process
Type (Rotary, Linear, Incremental, Absolute)
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: Confidential
7
Types of Encoders
Encoder
Rotary Encoder
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Linear Encoder
: Confidential
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Types of Encoders
Linear
Rotary
• Convert Angular Position into
Analog or Digital Signal
• Convert Linear distance
movement to Analog or Digital
Signal
• Encoders for rotary motion and
measuring angle, speed or
velocity
• Encoders for measuring
distance travelled, positioning,
location information.
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: Confidential
9
Types of Encoders
Encoder
Linear Encoder
Wire Draw
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Linear with Scale
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Types of Encoders
Wiredraw
With Scale
• Convert pulled wire length
distance to feedback
• Absolute and Incremental
• Analog, digital or Bus feedback
interfaces
• Distance: up to 50m
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• Two part devices; Active Head,
Passive Scale
• Absolute Positioning
• Scale : Magnetic Tape or
Elements
• Hiperface, SSI, Bus Interfaces
• Distance: up to 1700m
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Types of Encoders
Encoder
Rotary Encoder
Incremental
Linear Encoder
Absolute
Wire Draw
Incremental
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Linear with Scale
Absolute
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Incremental Encoders
Incremental

Produces electrical pulses or increments
with linear or rotary motion

Signals can be square or sinusoidal waves

Signals start over at power up, or after a
power failure. In other words, an incremental
encoder does not retain position after a
power cycle

Incremental encoders are typically used for
speed or applications that do not require
absolute position
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13
Absolute Encoders
Absolute
Code disc for absolute
encoders
LED
Lens
Provides a unique value for every shaft or
linear position

Absolute encoders retain their position after
a power cycle

Signals typically use SSI, parallel, or field bus
interfaces (Ethernet/IP, EtherCAT, Profinet,
Devicenet, CANopen, Profibus, etc)

Absolute encoders are used in applications
were position information is necessary
Scanning mask
Code disc
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
PhotoElements
: Confidential
14
Encoder Selection Process
Type (Rotary, Linear, Incremental, Absolute)
Electrical Interface
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: Confidential
15
Types of Encoders
Encoder
Rotary Encoder
Incremental
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Absolute
: Confidential
16
Incremental Encoders
Output Channels
:
Incremental encoders
-
:
Resolution
-
:
produce electrical pulses or increments (usually as a
square wave) with linear or rotary motion of the encoder
The number of pulses or increments per channel, per
revolution. Also known as Pulses Per Revolution, or PPR
Quadrature:
-
-
The standard convention is to output two square wave
channels along with their complements
Channels A and B are offset by ¼ of a cycle – using all four
channels with this output, we can interpolate 4 positions
within one pulse cycle. This is known as “quadrature”
The 1/4th offset also allows us to see which direction the
encoder is turning based on what channel is leading. If
channel A goes high first followed by channel B, we can
determine the direction of rotation, and visa versa.
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: Confidential
: Name (Date)
17
Incremental Encoders
Electrical Signals
:
Output Voltages
-
:
HTL (High Threshold Logic)
-
:
Also known as “push pull”
The output voltage will be the same as the supply
voltage (e.g if the supply on the encoder is 24V,
the output signal will also be ~24V)
TTL (Transistor Transistor Logic)
-
:
Standard output voltages are HTL, TTL or Open Collector.
These refer to the amplitude of the square waves
Also known as a “differential line driver” or “RS422”
The output voltage will always be 5V regardless of
the supply voltage on the encoder
Open Collector
-
Instead of outputting a signal of a specific voltage or
current, the output signal is applied to the base of an
internal NPN transistor whose collector is externalized
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: Confidential
: Name (Date)
18
Incremental Encoders
Interface Summary
Incremental Encoder – Electronic Interface Summary
•
•
Standard Supply voltages are 5VDC, 10-32 VDC, and 8-24VDC
Standard outputs are TTL, HTL and Open collector
Incremental
Electronic Interface
TTL / RS 422
Supply = 5V
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TTL / RS 422
Supply = 10 ... 32V
: Confidential
HTL / Push Pull
Supply = 10 ... 32V
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Open Collector
Supply = 8-24 V
Absolute Encoders
Singleturn vs Multiturn Absolute Encoders
Encoder
Rotary Encoder
Incremental
Absolute
Singleturn
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Multiturn
: Confidential
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Singleturn and Multiturn Absolute
Multiturn
Singleturn
• Measures the Absolute position
within 1 revolution/turn
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: Confidential
• Measures the Absolute position
within 1 revolution/turn
• In Addition, measures the
number of revolutions as well.
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Absolute Encoder Interfaces
Absolute
Electronic Interface
Parallel
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SSI
: Confidential
BUS
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Parallel Output
:
Parallel Output
-
:
Connection
-
:
First form of communication for absolute encoders
Point-to-point communication where each output wire
represents a different data bit
:
Benefits
-
Direct output to digital inputs
Fast (60us typically)
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Drawbacks
-
: Confidential
Complex cabling due to separate bit wires
High cost
: Name (Date)
23
Synchronous Serial Interface (SSI)
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Synchronous Serial Interface (SSI)
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:
Connection
-
:
Very common serial interface standard for industrial applications
Developed by Stegmann in 1984 for absolute encoders – now in many products
Point-to-point connection from a master (PLC, microcontroller) to a slave (encoder)
:
Benefits
-
Simple cabling, especially compared to
parallel outputs
Fast communication speeds
Low cost
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: Confidential
Drawbacks
-
Point-to-point connection, topology restrictions
: Name (Date)
24
Network Encoders
:
What do we (or the customer) mean when we say “network
encoder”?
- A network is a collection of products (sensors, HMIs, processes, etc) that are
connected to a central controller or share information between parts.
- Also known as Field Bus
- Example: an Internet VPN (virtual
private network):
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25
Field Bus Interfaces
:
Field Bus
-
:
Benefits
-
:
Industrial network system that connects multiple products in a manufacturing plant or on a
machine
Products are no longer point-to-point which allow multiple products to be connected to one
controller
Generally does not require as many cables as a point to point configuration, and cables do not
need to be as long. This saves on system costs.
Typically the controller has more flexibility for configuration and information gathering
Disadvantages
-
The network topologies are generally more complex
Individual components cost more than standalone products (potential system savings, however)
: SICK, Inc.
: Confidential
: Name (Date)
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SICK Absolute Encoder Fieldbus Interfaces
AFx60 Series
ATM60 Series
: SICK, Inc.
: Confidential
: Name (Date)
27
Electrical Interface Summary
Things to know when choosing an encoder
:
:
Incremental Encoders
- Resolution (PPR)
- Supply Voltage
- Output Voltage (HTL, TTL or Open
Collector)
Absolute Encoders
- Resolution (singleturn, multiturn)
- Output type
▪
▪
▪
- Programmable Encoders:
DFS60 and DFS2x encoders let you
program ALL electrical configurations
except an open collector output
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: Confidential
Parallel (output voltage needed)
SSI
Fieldbus
- Programmable Encoders
Programmable options for SSI encoders to
program the resolution. All field bus
encoders are programmable over their
respective networks
: Name (Date)
28
Encoder Selection Process
Type (Rotary, Linear, Incremental, Absolute)
Electrical Interface
Mechanical Considerations
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: Confidential
29
Mechanical Characteristics
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:
:
Housings and Connection
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Housing Size
-
Cable or Connector
Shafts
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Solid, blind hollow, through hollow
-
Sizes, shaft load
Flange
-
Face mounting flange
-
Servo flange
-
Square Flange
-
Tethers
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: Confidential
30
Encoder Selection Process
Type (Rotary, Linear, Incremental, Absolute)
Electrical Interface
Mechanical Considerations
: SICK, Inc.
: Confidential
31
Product Overview - Rotary Encoders
Absolute Singleturn Encoders
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: Confidential
Absolute Multiturn Encoders
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Product Overview - Linear Encoders
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: Confidential
33
Key Products in 2013
Choice encoders that will solve most applications
DFS60 with PGT-10-S
Programming Tool
•
•
•
Handheld, battery
operated programming
tool
Easy menu structure for
fast setup and flexibility
Can be used for
diagnostics with the
display or as a cloning
module
: SICK, Inc.
DFS20/25
Incremental Encoder
•
USA sized encoders with
SICK’s “F”-Technology:
•
Wide set bearings for even
shaft loading
•
•
•
Absolute single- and multiturn encoders with
EtherNet/IP, EtherCAT,
and Profinet interfaces
•
Device Level Ring (DLR)
functionality with the
EtherNet/IP version
Metal code disc for high
vibration and temperature
Programmable using the
PC-based tool
: Confidential
BCG Wiredraw
with Analog Output
AFx60 Series
With Ethernet
•
Superior diagnostics for
temperature, speed,
runtime, and many more
•
Compact wiredraw
encoder for applications in
tight spaces
•
Up to 10m of measuring
length
•
Analog output scalable
directly on the encoder for
fast commissioning
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Fields of applications
Machine Tooling
Packaging
Print & Paper
Wood industry
Automotive
Ports & Cranes
Handling
… And many more
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: Confidential
35
Application Examples
OVERHEAD CRANE– AFM60 EtherNet/IP used to track position of crane
CONVEYORS – DKV60 used to track speed of conveyor
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: Confidential
36
Application Examples
WIND TURBINE – Absolute encoder AFM60 for gandala and blade angle tracking
BOTTLING – Absolute encoder AFS60 to track position of fillers
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: Confidential
37
Application Examples
STADIUM ROOF – Position with KH53 Linear Encoder
LIFT APPLICATIONS – Height and Width positioning using BGC Wiredraw Encoders
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: Confidential
38
Additional Resources
SICK University Tour
March – May 2013
Tech Tuesdays
Check www.sickusa.com for schedule
Product Training
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Demo Cases
: Confidential
Demonstration Videos & Application
Animations
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Marketing Tools
Encoder Catalog
Encoder Selection Guide
Application Book
*Update in 2013
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: Confidential
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:
Thank you for your attention.