There are two basic types of rotary encoders: absolute and incremental. Absolute rotary encoders provide a coded angle information and avoid time consuming reference measurements or calculation routines in the controller. Incremental rotary encoders provide a square wave or sinusoid output signal and enable counters and PLC to calculate position, speed and distance.

Rotary encoders come in four mechanical configurations: modular (kit-type), shaft, blind hollow-shaft and true hollow-shaft.

The Difference Between Absolute and Incremental Rotary Encoders

There are a few differences between absolute and incremental rotary encoders. Incremental encoders have output signals that repeat over the full range of motion. When the incremental encoder is turned on, the position of an incremental encoder is not known since the output signals are not unique to any singular position. Once an incremental encoder passes an index, which can be a single- or multi-track design, the position information is absolute from that point forward.

Absolute encoders have a unique value (voltage, binary count, etc) for each mechanical position. When an absolute encoder is turned on, the position of an absolute encoder is known. The similarities of both absolute and incremental encoders are form and the issues of count and directional information. They can be obtained from both absolute and incremental encoders equally.

Gurley offers three technologies for rotary encoders: incremental, true absolute and our patented Virtual Absolute(R) brand.

For more information on these offerings, please click on one of the selections detailed above (both true absolute and Virtual Absolute are detailed in the Rotary Absolute section).  
For general information on Virtual Absolute technology please visit www.virtualabsolute.com.  

 

GPI ROTARY ENCODER SELECTION GUIDE

Note: For all incremental encoders, max. resolution is after 4x quadrature decode in the user's electronics

 
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Gurley Model 7700 Incremental and Virtual Absolute Encoder

Series: 7700

Dia.: < 1.7"<46mm

Max. Accuracy: Call factory

Max. Resolution: 20,000
(Counts/Rev.)

Notes: Modular Kit Encoder

Gurley LP20 Series Modular Incremental Encoder

Series: LP20

Dia.: Call

Max. Accuracy: Call factory

Max. Resolution: 32,768
(Counts/Rev.)

Notes: Modular Kit Encoder

Gurley Model 9710 Modular Incremental Encoder

Series: 9710

Dia.: < 23" < 584mm

Max. Accuracy: Call factory

Max. Resolution: 80x linecount
(Counts/Rev.)

Notes: Modular Encoder

 
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Gurley Model R112 Rotary Incremental Mini-Encoder

Series: R112

Dia.: 0.47" 12mm

Max. Accuracy: 500

Max. Resolution: 32,000
(Counts/Rev.)

Notes: Solid or Blind Hollow Shaft

Gurley Series M136 Magnetic Rotary Encoders

Series: M136

Dia.: 0.86" 22mm

Max. Accuracy: 2048

Max. Resolution: 8192
(Counts/Rev.)

Notes: Compact Magnetic Encoder

Gurley Models R119 and R120 - Rotary Incremental Mini-Encoders

Series: R119/R120

Dia.: 0.75" 19/20mm

Max. Accuracy: 1,024

Max. Resolution: 65,536
(Counts/Rev.)

Notes: Solid or Blind Hollow Shaft

Gurley Series 9x11S Rotary Incremental Encoder

Series: 9x11S

Dia.: 1.1" 28mm

Max. Accuracy: 1,800

Max. Resolution: 144,000
(Counts/Rev.)

Notes: Two Accuracy Grades

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Gurley Model R137 Rotary Incremental Encoder

Series: R137

Dia.: 1.5" 37mm

Max. Accuracy: 3,600

Max. Resolution: 230,400
(Counts/Rev.)

Notes: Solid or Blind Hollow Shaft

Gurley Series 9x20 Rotary Incremental Encoder

Series: 9x20

Dia.: 2.0" 51mm

Max. Accuracy: 4,500

Max. Resolution: 144,000
(Counts/Rev.)

Notes: Solid or Blind Hollow Shaft

Gurley Series R158 Rotary Incremental Encoders

Series: R158

Dia.: 2.28" 58mm

Max. Accuracy: 5,000

Max. Resolution: 1,000,000
(Counts/Rev.)

Notes: -40 to 100 C option; 60N/40N

Gurley Series 9X25 Rotary Incremental Encoders

Series: 9x25

Dia.: 2.5" 63mm

Max. Accuracy: 9,000

Max. Resolution: 200,000
(Counts/Rev.)

Notes: -Three Accuracy Grades

Gurley Series 835S Rotary Incremental Encoders

Series: 8x35

Dia.: 3.5" 89mm

Max. Accuracy: 11,250

Max. Resolution: 900,000
(Counts/Rev.)

Notes: Two Accuracy Grades

Gurley Series 8X60 Angle Encoder

Series: 8x60

Dia.: 6.0" 152mm

Max. Accuracy: 18,000

Max. Resolution: 3,600,000
(Counts/Rev.)

Notes: Metrology Grade, Solid or
Hollow Shaft

 
 
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Gurley Model R108 Rotary Incremental Micro-Encoder

Series: R108

Dia.: 0.31" 8mm

Max. Disc Linecount: 512

Max. Resolution: 2,048
(Counts/Rev.)

Notes: Unique Blind Hollow Shaft

Gurley Model R112 Rotary Incremental Mini-Encoder

Series: R112

Dia.: 0.47" 12mm

Max. Disc Linecount: 500

Max. Resolution: 32,000
(Counts/Rev.)

Notes: High Resolution Solid & Blind Hollow Shaft

Gurley Series M122 Magnetic Rotary Encoders

Series: M112

Dia.: 0.86" 22mm

Max. Disc Linecount: 2048

Max. Resolution: 8192
(Counts/Rev.)

Notes: Compact Magnetic Encoder

Gurley Models R119 and R120 Rotary Incremental Mini-Encoders

Series: R119/R120

Dia.: 0.75" 19/20mm

Max. Disc Linecount: 1,024

Max. Resolution: 65,536
(Counts/Rev.)

Notes: Solid or Blind Hollow Shaft

Gurley Model R137 Rotary Incremental Encoder

Series: R137

Dia.: 1.5" 37mm

Max. Disc Linecount: 3,600

Max. Resolution: 230,400
(Counts/Rev.)

Notes: Solid or Blind Hollow Shaft

Gurley Series 9x20 Rotary Incremental Encoder

Series: 9x20

Dia.: 2.0" 51mm

Max. Disc Linecount: 4,500

Max. Resolution: 144,000
(Counts/Rev.)

Notes: Solid or Blind Hollow Shaft

Gurley Series R176H Rotary Incremental Encoders

Series: R176H

Dia.: 3.0" 76mm

Notes: True Hollow Shaft

Gurley Series 835H Hollow-Shaft Encoders

Series: 8x35H

Dia.: 3.5" 89mm

Max. Disc Linecount: 11,250

Max. Resolution: 900,000
(Counts/Rev.)

Notes: Hollow Shaft, Three Accuracy Grades

Gurley Series 8X60 Angle Encoder

Series: 8x60

Dia.: 6.0" 152mm

Max. Disc Linecount: 18,000

Max. Resolution: 3,600,000
(Counts/Rev.)

Notes: Metrology Grade, Solid or Hollow Shaft

Gurley Series 9480H Angle Encoder

Series: 9480H

Dia.: 8.0" 203mm

Max. Disc Linecount: 18,000

Max. Resolution: 7,200,000
(Counts/Rev.)

Notes: Metrology Grade Hollow Shaft

 
 
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Gurley Model 7700 Incremental and Virtual Absolute Encoder

Series: 7700VA

Dia.: < 1.7" 45mm

Max. Resolution: 19 bits
(Words/Turn)

Notes: Modular Kit Encoder

Gurley Model 9710 Virtual Absolute Encoder

Series: 9710VA

Dia.: up to 23" 600mm

Max. Resolution: 22 bits
(Words/Turn)

Notes: Modular Encoder

 
 

Gurley Models A19 & A20 Absolute Encoder

Series: A19

Dia.: 0.75" 19/20mm

Max. Resolution: 15 bits
(Words/Turn)

Notes: Miniature, Low-Cost True Absolute

Gurley Model A37 Absolute Encoder

Series: A37

Dia.: 1.5" 37mm

Max. Resolution: 12 bits
(Words/Turn)

Notes: Compact, Low-Cost True Absolute

Gurley Model A36 Absolute Encoder with SSI Output

Series: A36

Dia.: 36mm

Max. Resolution: 25 bits (single + multi-turn)
(Words/Turn)

Notes: True absolute multi-turn

Gurley Series Vx20 Virtual Absolute Encoder

Series: Vx20

Dia.: 2.0" 51mm

Max. Resolution: 19 bits
(Words/Turn)

Notes: Virtual Absolute

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Gurley Model A25S Absolute Encoder

Series: A25

Dia.: 2.50" 64mm

Max. Resolution: 17 bits
(Words/Turn)

Notes: High Resolution, Highest Accuracy +/-15"

Gurley Model M58 Absolute Encoder with SSI Output

Series: M58

Dia.: 2.28" 58mm

Max. Resolution (Words/Turn): 21 bits single turn 58 bits (single + multi-turn)

Notes: High Resolution Multi-turn

Gurley Model A58 Absolute Encoder

Series: A58

Dia.: 2.28" 58mm

Max. Resolution: 17 bits
(Words/Turn)

Notes: High Resolution, Low-cost True Absolute

Gurley Model A90 Absolute Encoder

Series: A90

Dia.: 3.5" 90mm

Max. Resolution: 22 bits
(Words/Turn)

Notes: 22 bitsHigh Resolution/Accuracy, True Absolute

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Gurley Model A08 Rotary Absolute Micro-Encoder

Series: A108

Dia.: 0.3" 8mm

Max. Resolution: 12 bits
(Words/Turn)

Notes: Compact Magnetic Encoder

Gurley Series M122 Magnetic Rotary Encoders

Series: M122

Dia.: 0.86" 22mm

Max. Resolution: 13 bits
(Words/Turn)

Notes: Compact Magnetic Encoder

Gurley Models A19 & A20 Absolute Encoder

Series: A19

Dia.: 0.75" 19/20mm

Max. Resolution: 15 bits
(Words/Turn)

Notes: Miniature, Low-Cost True Absolute

Gurley Model A36 Absolute Encoder with SSI Output

Series: A36

Dia.: 36mm

Max. Resolution: 25 bits (single + multi-turn)
(Words/Turn)

Notes: True absolute multi-turn

Gurley Model A37H Hollow-Shaft Absolute Encoder

Series: A37H

Dia.: 37mm

Max. Resolution: 23 bits
(Words/Turn)

Notes: Miniature, Low-Cost True Absolute

Gurley Series Vx20 Virtual Absolute Encoder

Series: Vx20

Dia.: 2.0" 51mm

Max. Resolution: 19 bits
(Words/Turn)

Notes: Solid or Blind Hollow Shaft

Gurley Series VX35H Virtual Absolute Encoder

Series: Vx35H

Dia.: 3.5" 89mm

Max. Resolution: 20 bits
(Words/Turn)

Notes: Hollow Shaft

Gurley Model V860H Virtual Absolute Encoder

Series: V860H

Dia.: 6.0" 152mm

Max. Resolution: 22+ bit Hollow Shaft
(Words/Turn)

Notes: 1 MHz Max. Data Update Rate

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Gurley Model HR2A High-resolution Interpolator

Series: HR2A Interpolator

Description: Available for various models

Gurley Models HR2B and HR2C High Resolution Interpolators

Series: HR2B & C Interpolators

Description:
Available with models 9710 and 9717 and generates quadrature square waves at any 1, 2, 5, 10 or 20 times the line count on the disc or scale

ISC3N Interface Card

Series: ISC3N Interface Card

Description:
Provides an interface between an IBM® PC or compatible computer and most incremental encoders; handles up to 3 encoders simultaneously

Gurley Model HDT Heavy Duty Enclosure

Series: HD Heavy Duty Enclosure

Description:
Extremely robust housing to protect Model 925 encoders; Separate shaft/bearing assembly completely isolates the encoder from external shaft loads, shock, vibration and contamination

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Gurley Models SCA, SCD, and SCE Shaft Couplings

Series: Couplings

Description:
Check out our SCA coupling line

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Displays

Series: Digital displays: Incremental and Absolute

 
 

Need a special encoder not listed above?  
Gurley produces custom encoders at standard lead times and prices.  
Contact Sales for information.