© 2012 CUI Inc

Panel Mount Encoders

© 2012 CUI Inc

IntroductionPurposeThe purpose of this training module is to familiarize you with the principles of panel mount rotary encoders and the key features of the ACZ and C14 series available through Digi-Key.

Objectives To explain how panel mount rotary encoders fundamentally work and provid

definitions to key specification and principles

Describe the difference between mechanical and optical encoder technology

Describe the key features of CUI’s ACZ and C14 series

Detail typical applications these encoder are used in

Content: 19 pages

Learning Time: 15 minutes

© 2012 CUI Inc

What Are Encoders?

Encoders are a type of sensor designed to provide rotation information

An encoder sends out a pulse each time it is moved a certain number of degrees

A microprocessor counts these pulses and calculates rotation

© 2012 CUI Inc

What are panel mount encoders?

Panel mount encoders are designed for use in human interface applications

They provide an accurate and inexpensive method for user manipulation of electronic products

© 2012 CUI Inc

Why an Encoder?

Encoders: Consistent Accurate Digital

Potentiometers: Inconsistent Accuracy is hardware dependent Analog

DIGITAL

vs

ANALOG

© 2012 CUI Inc

ApplicationsPanel mount encoders, like the ACZ and C14 series, are ideal for applications in many industries

Defense & Aerospace

Simulators, cockpit control Handheld, mobile, fixed radios Ground control, weapon control Marine applications

Rescue & Security

CCTV (closed circuit TV) Handheld, mobile, fixed radios Rescue tools and equipment

Infrastructure Control

Traffic control for car, railway Traffic information systems Power plant and energy distribution Communication network control

Light & Sound

Studio mixers and cutting PA and on-stage equipment On-site transmission equipment

© 2012 CUI Inc

Applications continued

Industrial Automation

Motor drives PLCs and control systems Remote control units Tooling machines

Building & Facilities

Heater and air conditioning Lock and access systems Remote control units Illumination control

Research & Science

Electronic lab and instrumentation Meteorology and geology measures Petro and pharmaceutical measures Other physical measures

Transportation Vehicle

Construction machinery cockpits Remote control for construction Rail car and ship cockpits Car side passenger information

Consumer

Audio equipment/home entertainment White goods (Washer/Dryer) Espresso machine Fitness and wellness equipment

Medical

Surgery tools Analysis devices X-ray, ultrasonic and MRI Life recovery and sustainment

© 2012 CUI Inc

Important Specifications

PPR(pulses per revolution)

The number of square wave pulses per revolution of the encoder shaft per channel, this measure is also known as “resolution”

CPR (counts per revolution)

The number of quadrature state changes per revolution, or PPR x 4

Detents

These prevent unwanted rotation and provide a “click” every time the shaft is rotated a certain number of degrees

Push Switch

The encoder shaft can be pressed down to actuate a simple SPST switch

© 2012 CUI Inc

Pulses

1 full cycle

Pulse = One full square wave cycle. A transition from low to high to low.

© 2012 CUI Inc

Output Square wave output over two channels

The signals are identical except they are slightly offset

By detecting which signal is leading, the direction of rotation can be monitored

Clockwise Rotation Counter-Clockwise Rotation

© 2012 CUI Inc

Output Continued

Microcontrollers use differentmethods for counting

Pulses on one channel 1 count per pulse

Pulses on two channels Using both channels doubles the

number of counts

Quadrature state changes 4 counts per cycle

Quadrature Truth Table

PositionState

A B

1 0 0

2 1 0

3 1 1

4 0 1

1 0 0

2 1 0

3 1 1

4 0 1

1 0 0

2 1 0

3 1 1

4 0 1

© 2012 CUI Inc

Sinking and Sourcing

Sinks provide paths to ground

Sources provide paths to a voltage

A sink needs a source to work and vice versa A faucet needs a sink, and a sink needs a faucet

CUI Inc panel mount encoders sink current, requiring a source to work properly

© 2012 CUI Inc

Mechanical vs. Optical Technology

Mechanical Inexpensive Rugged Variable source

voltage levels

Optical Cleaner Output Longer lasting Less external circuitry Higher resolution

© 2012 CUI Inc

How Optical Encoders Work

Attached to the shaft, inside the encoder body is a wheel a with slits cut in at regular intervals

A beam of light is aimed across the code wheel

A detector on the other side is used to tell if the beam is being transmitted through a slit or blocked by the material between slits

As the shaft is turned, the light beam is alternately blocked (state=0) or transmitted (state=1)

© 2012 CUI Inc

Features Compact – 15 mm width

Rugged – Metal body construction and optional IP65 rating

Quadrature output

Clean square wave output

Life – 1,000,000 cycles

C14 Optical Encoder Series

Available options 16 & 32 PPR (64 & 128 CPR)

Push switch or no switch

Detents or no detents

6 different termination types

3.175, 6, 6.35 mm shaft diameter

5 different mounting types

Optional IP65 rating

© 2012 CUI Inc

How Mechanical Encoders Work A code wheel with contacts turns inside the unit

as the encoder shaft is turned

When contact is made the voltage at the output is pulled up

When contact is broken the output is pulled low

Stationary contact

Moving contact

© 2012 CUI Inc

Switch Bounce and Debounce in Mechanical Encoders

An ideal switch will have two states, on and off, and it will instantlymove to one of these positions

In the real world a switch will hover, or bounce, between these states during switching operations

To compensate for this effect, switches need “debounce” circuitryand/or programming

Ideal Real world Bounce

© 2012 CUI Inc

ACZ Mechanical Encoder Series

Available options

12, 15, 20 ,30 PPR

Push switch or no switch

Detents or no detents

15, 20, 25 mm shaft length

Horizontal or vertical mounting

© 2012 CUI Inc

Summary CUI’s ACZ and C14 series encoders are designed to provide an accurate

and inexpensive method for user input across a wide range of applications

The ACZ series utilizes mechanical encoder technology, offering a rugged, low cost solution

The C14 series utilizes optical encoder technology, offering a clean signal and long cycle life for high precision applications

Learn More

View CUI’s panel mount encoders

View CUI’s full Encoder product portfolio

© 2012 CUI Inc

www.cui.com