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Rotary Encoders



Rotary Incremental


Rotary Absolute

Accessories (interface, decoding and interpolation cards, enclosures, and couplings)



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

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

Rotary Incremental Encoders




Modular, Kit-Type Versions
 
Series Datasheet Dia. Max. Accuracy Max. Resolution
(Counts/Rev.)
Notes
7700 < 1.7"
<46mm
Call factory 20,000 Modular Kit Encoder
LP20 Call Call factory 32,768 Modular Kit Encoder
9710 < 23"
< 584mm
Call factory 80x linecount Modular Encoder

 

Shafted Versions
 
Series Datasheet Dia. Max. Accuracy Max. Resolution
(Counts/Rev.)
Notes
R112 0.47"
12mm
500 32,000 Solid or Blind Hollow Shaft
M136 0.86"
22mm
2048 8192 Compact Magnetic Encoder
R119/R120 0.75"
19/20mm
1,024 65,536 Solid or Blind Hollow Shaft
9x11 1.1"
28mm
1,800 144,000 Two Accuracy Grades
R137 1.5"
37mm
3,600 230,400 Solid or Blind Hollow Shaft
9x20 2.0"
51mm
4,500 144,000 Solid or Blind Hollow Shaft
R158 2.28"
58mm
5,000 1,000,000 -40 to 100 C option; 60N/40N
9x25 2.5"
63mm
9,000 200,000 Three Accuracy Grades
8x35 3.5"
89mm
11,250 900,000 Two Accuracy Grades
8x60 6.0"
152mm
18,000 3,600,000 Metrology Grade, Solid or 
Hollow Shaft 




Blind Hollow and True Hollow Shaft Versions
 
Series Datasheet Dia. Max. Disc Linecount Max. Resolution
(Counts/Rev.)
Notes
R108 0.31"
8mm
512 2,048 Unique Blind Hollow Shaft
R112 0.47"
12mm
500 32,000 High Resolution Solid &
Blind Hollow Shaft
M122 0.86"
22mm
2048 8192 Compact Magnetic Encoder
R119/R120 0.75"
19/20mm
1,024 65,536 Solid or Blind Hollow Shaft
R137 1.5"
37mm
3,600 230,400 Solid or Blind Hollow Shaft
9x20 2.0"
51mm
4,500 144,000 Solid or Blind Hollow Shaft
R176H 3.0"
76mm
    True Hollow Shaft
8x35H 3.5"
89mm
11,250 900,000 Hollow Shaft, Three Accuracy Grades
8x60 6.0"
152mm
18,000 3,600,000 Metrology Grade, Solid or 
Hollow Shaft 
9480H 8.0"
203mm
18,000 7,200,000 Metrology Grade Hollow Shaft 

Rotary Absolute Encoders




Modular, Kit-Type Versions
 
Series Datasheet Dia. Max. Resolution
(Words/Turn)
Notes
7700VA < 1.7"
45mm
19 bits Modular Kit Encoder
9710VA up to 23"
600mm
22 bits Modular Encoder




Shafted Versions
 
Series Datasheet Dia. Max. Resolution
(Words/Turn)
Notes
A19 0.75"
19/20mm
15 bits Miniature, Low-Cost True Absolute
A37 1.5"
37mm
12 bits Compact, Low-Cost True Absolute
A36 36mm 25 bits (single + multi-turn) True absolute multi-turn
Vx20 2.0"
51mm
19 bits Virtual Absolute
A25 2.50"
64mm
17 bits High Resolution, Highest Accuracy +/-15"
M58
2.28"
58mm
21 bits single turn
58 bits (single + multi-turn)
High Resolution Multi-turn
A58 2.28"
58mm
17 bits High Resolution, Low-cost True Absolute
A90 3.5"
90mm
22 bits High Resolution/Accuracy,
True Absolute



Blind Hollow and True Hollow Shaft Versions
 
Series Datasheet Dia. Max. Resolution
(Words/Turn)
Notes
A108 0.3"
8mm
12 bits Compact Magnetic Encoder
M122 0.86"
22mm
13 bits Compact Magnetic Encoder
A19 0.75"
19/20mm
15 bits Miniature, Low-Cost True Absolute
A36 36mm 25 bits (single + multi-turn) True absolute multi-turn
A37H 37mm 23 bits Miniature, Low-Cost True Absolute
Vx20 2.0"
51mm
19 bits Solid or Blind Hollow Shaft
Vx35H 3.5"
89mm
20 bits  Hollow Shaft
V860H 6.0"
152mm
22+ bit Hollow Shaft 1 MHz Max. Data Update Rate

Accessories





All Accessories
 
Series Datasheet Description
HR2A
Interpolator

Available for various models

HR2B & C
Interpolators

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

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

HD Heavy Duty Enclosure

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

Couplings

Check out our SCA coupling line

Displays

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.