encoder selection guide_2009-sick

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Find the right encoder for your application.

selection Guide for encoders

2 s e l e c t i o n G u i d e f o r e n c o d e r s | s i c k - s t e G M a n n 2 0 0 9 - 0 8

incremental, absolute, linear... Which encoder is right for your application?

Often the differences between two encoders seem to be small. This guide will help you find these differences quickly and easily, enabling you to choose the right encoder product family.

What is the difference between ...?

and between ...?

incremental and absolute

•Counts pulses from 1 to n•Reference run (zero pulse) necessary to obtain absolute

position value• The number of pulses defines the resolution

•Measures the absolute position from 1 to n•Every measuring step is defined by a unique (absolute)

code pattern• The number of steps defines the resolution

absolute singleturn and absolute Multiturn

•Variant of an Absolute Encoder•Measures the absolute position from 1 to n within one

revolution

•Variant of an Absolute Encoder•Measures the absolute position from 1 to n within one

revolution• In addition measures the number of revolutions

Wire draw encoders and linear encoders

•Measures lengths between A and B•Consists of a Rotary Encoder and a wire draw mechanism• The wire is mounted to the moving part• The encoder is fixed

•Measures lengths between A and B•Consists of read head and scale• The read head is mounted to the moving part• The scale is fixed

3s i c k - s t e G M a n n | s e l e c t i o n G u i d e f o r e n c o d e r s2 0 0 9 - 0 8

What should be measured?angle, speed, velocity or distance?

from speed monitoring to tracking products on a conveyor, sick helps you select an encoder based on the parameters that need to be measured.

angle, speed or Velocity = rotary encoders (selection guide pages 4-5)

distance = linear encoders (selection guide page 6)

absolute singleturn encoders

ARS20/25

linear encoders with scale

KH53 KH53 A L230

incremental Wire draw encoders

PKS PRF

absolute Wire draw encoders

BKS/XKS BTF

DFS60

DKS40 DKV60 DGS34/35

incremental encoders

SKM36 + fieldbus moduleAFM60 ATM60 ATM90 SRM64/50 + fieldbus module

absolute Multiturn encoders

AFS60

ARS60

DRS60/61 DRS25/26

DGS20/25 DGS21/22

DRS20/21


incremental encoders

incrementalencoders

dfs

60

dr

s60/

61

dr

s25/

26

dr

s20/

21

dG

s20/

25

dG

s21/

22

ld20

dks

40

dkV

60

dG

s34/

35

should an absolute position always be measured?

Yes

no ■ ■ ■ ■ ■ ■ ■ ■ ■How many absolute turns should be measured?

no absolute measurement ■ ■ ■ ■ ■ ■ ■ ■ ■1

2 or more

Which interface connection is required?

ttl (5 V) pulses/ Htl (10 to 30 V) pulses ■ ■ ■ ■ ■ ■ ■ ■ ■Parallel data word

ssi data word

Bus connectivity, data word

What is the maximum diameter available?

40 mm ■60 mm ■ ■ ■3.5 in ■2 in ■ ■ ■2.5 in ■ ■

What type of mounting shaft is required?

Face mount flange solid shaft ■ ■ ■ ■Servo flange solid shaft ■ ■ ■ ■ ■Square flange ■ ■ ■Blind hollow shaft ■ ■ ■ ■through hollow shaft ■ ■ ■ ■Measuring wheel ■

is a shaft diameter > 16 mm required?

Yes ■no ■ ■ ■ ■ ■ ■ ■

What resolution is required (pulses/steps)?

Max. 2,500 ■ ■ ■ ■Max. 8,192 ■ ■ ■Max. 32,768 ■> 32,768 ■

is a solution enabling program-ming by the customer required (resolution, zero-pulse …)?

Yes ■ ■ ■ ■no ■ ■ ■ ■ ■ ■ ■ ■ ■

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absolute encoders

absolute singleturn encoders

absolute Multiturnencoders

afs6

0

ars6

0

ars2

0/25

afM

60

atM

60

atM

90

skM

36 +

fie

ldbu

s mod

ule

srM

64/5

0 +

field

bus m

odul

e


Yes ■ ■ ■ ■ ■ ■ ■ ■no

How many absolute turns should be measured?

no absolute measurement

1 ■ ■ ■2 or more ■ ■ ■ ■ ■


ttl (5 V) pulses/ Htl (10 to 30 V) pulses

Parallel data word ■ ■ssi data word ■ ■ ■ ■ ■ ■ ■ ■Bus connectivity, data word ■ ■ ■ ■

What is the maximum diameter available?

40 mm ■60 mm ■ ■ ■ ■ ■90 mm ■2 in ■2.5 in ■ ■

What type of mounting shaft is required?

Face mount flange solid shaft ■ ■ ■ ■ ■ ■Servo flange solid shaft ■ ■ ■ ■ ■ ■Square flange ■ ■Blind hollow shaft ■ ■ ■ ■ ■through hollow shaft ■ ■ ■ ■ ■Measuring wheel

is a shaft diameter > 16 mm required?

Yes

no ■ ■ ■ ■ ■ ■ ■ ■What resolution is required (positions/turn)?

Max. 2,500

Max. 8,192 ■ ■Max. 32,768 ■ ■ ■> 32,768 ■ ■ ■

is a solution enabling program-ming by the customer required (resolution, zero-pulse …)?

Yes ■ ■ ■ ■ ■ ■no ■ ■ ■ ■ ■ ■ ■ ■

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linear encoders

incremental Wire draw encoders

absolute Wire draw encoders

linear encoders with scale

Pks

Prf

Bks

Xks

Btf

kH53

kH53

a

l230


Yes ■ ■ ■ ■ ■ ■no ■ ■


ttl (5 V) pulses/ Htl (10 to 30 V) pulses ■ ■HiPerface® ■ ■ssi data word ■ ■ ■ ■ ■ ■Bus connectivity, data word ■ ■ ■ ■

are there continuous mount-ing points available across the measuring length?

Yes ■ ■ ■no ■ ■ ■ ■ ■

What are the mounting tolerances?

low ■ ■ ■ ■ ■ ■ ■Medium ■ ■High ■

What measuring length is required?

up to 5 m ■ ■ ■ ■ ■ ■ ■ ■up to 40/50 m ■ ■ ■ ■ ■up to 548 m ■ ■up to 1,700 m ■

What resolution is required? 0.1 to 0.05 mm ■ ■ ■ ■ ■ ■0.025 mm ■ ■ ■0.001 mm ■

Maximum number of measuring cycles?

up to 800,000 ■ ■ ■up to 1,000,000 ■ ■Infinite ■ ■ ■

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Definition of Technical Terms

accuracyDeviation between the real and the measured position

accuracy of repeatability/reproducibilityDeviationofthemeasuredvalueswhenadefinedpointisrepeatedly being approached under the same operating conditions

Baud rateSpeed of data transmission (bits/sec)

Bcd (Binary coded decimal) codeBinary presentation of a decimal number

Binary codeTwo digit numerical code consisting of 1s and 0s, which is capable of representing any integer decimal number

BitAbbreviation for “binary digit.” Smallest information unit of a binary system, whereby the values can be 1 or 0 (Yes/No decision).

dcDirect current

direction of rotationCan be clockwise (cw) or counterclockwise (ccw), as viewed from the shaft

enableControl input, by which the data outputs of absolute en-coders with parallel interface can be activated

flanges/shaftsDifferent mechanical adapters for the mounting of drive shafts to motors and gearboxes, as well as to gearwheels and pulleys

Gray codeSingle-step code. When changing from one value to the next,onlyonesingledatacodebitismodified.Worksforresolutions which can be expressed by 2n (e.g., 1024, 2048, 4096, etc.).

Gray excess codeGray code with cut-out (excess). Ensures that the single step characteristic of Gray code is maintained for resolu-tions which cannot be expressed by 2n (e.g., 360, 720, 1440, etc.).

JitterVariation of pulses during the transmission of digital sig-nals.Thepositionofthesignalflankscontinuallychange.

line driverOutput circuit which enables the use of a higher current to drive the signal over long distances

MultiturnIn addition to the singleturn data (positional information within one turn), the number of shaft revolutions (turns) is also transmitted

Protection classesDefinedaccordingtoDINVDE0470(EN60529,IEC529),are to be understood when the encoder is mounted. There are differences between protection classes for different housing styles and protection classes for shafts. The pro-tection class for housing depends mainly on the female connector being used or on the type of connector.

repeatabilityMaximum variation of the measured values produced dur-ingaminimumof5successivemovementstoadefinedposition, whereby the position is approached from the samedirectionandatafixedtemperature(accordingtoDIN 32878)

resolutionNumber of lines/steps per revolution. In case of abso-lute multiturn encoders, the resolution also includes the number of shaft turns.

shaft loadMechanical load on the encoder shaft in axial or radial direction

singleturn Positional information within one turn

speedMechanical turns of a shaft in revolutions per minute

ssiSynchronous serial interface. Standardized interface for serial data transmission.

Zero pulse (reference signal)An output signal given by an incremental encoder, which signifiestheendofonerevolution(360degreesofrotation)

Zero pulse widthLength of the marker/pulse reference

7130711/2009-08-01∙PrintedintheU.S.(2009-08)

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encoder selection guide_2009-sick

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