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Rotary Encoders

Rotary Encoders measure the number of rotations, the rotational angle, and the rotational position. Linear Encoders are also available to measure linear movement.

Related Contents

Primary Contents

Explanation of Terms

Resolution

The pulse count of an incremental signal output when the shaft revolves once, or the absolute address count.

Output Phase

The output signal count for an Incremental Encoder. There are 1-phase models (phase A), 2-phase models (phase A, phase B), and 3-phase models (phase A, phase B, and phase Z). The phase Z is an origin signal that is output once a revolution.

Output Phase Difference

When the shaft is rotated, this is the time difference between the rise or fall of the phase A and phase B signals, expressed as a proportion of the period of one signal, or as an electrical angle where one signal period equals 360°.
The difference between phase A and phase B as an electrical angle is normally 90°.

CW

The clockwise direction of rotation. Viewed from the end of the shaft, the shaft rotates clockwise. With an Incremental Encoder, phase A normally leads phase B in this rotation direction. With an Absolute Encoder, this is the direction of code increase.
The reverse of CW rotation is counterclockwise (CCW) rotation.

Output Duty Ratio

This is the ratio of the duration of high level during one period to the average period of pulse output when the shaft is rotated at a constant speed.

Maximum Response Frequency

The maximum frequency at which the signal can respond.

Rise and Fall Times of Output

The elapsed time from a 10% to 90% change in the output pulse.

Output Circuit

(1) Open-collector Output
An output circuit where the emitter of the output circuit transistor is the common and the collector is open.

(2) Voltage Output
An output circuit where the emitter of the output circuit transistor is the common and a resistor is inserted between the collector and the power supply to convert the output from the collector to a voltage.

(3) Line-driver Output
An output method that uses a special IC for high-speed, longdistance data transmission that complies with the RS-422A standard. The signal is output as a differential secondary signal, and thus is strong with respect to noise.
A special IC called a line receiver is used to receive the signal output from a line driver.

(4) Complementary Output
An output circuit with two output transistors (NPN and PNP) on the output.
These two output transistors alternately turn ON and OFF depending on the high or low output signal. When using them, pull up to the positive power supply voltage level or pull down to 0 V.
The Complementary Output allows flow-in or flow-out of the output current and thus the rising and falling speeds of signals are fast.
This allows a long cable distance.
They can be connected to open-collector input devices (NPN, PNP).

Starting Torque

The torque needed to rotate the shaft of the Rotary Encoder at startup.
The torque during normal rotation is normally lower than the starting torque. A shaft that has a waterproof seal has a higher starting torque.

Moment of Inertia

This expresses the magnitude of inertia when starting and stopping the Rotary Encoder.

Shaft Capacity

This is the load that can be applied to the shaft. The radial load is the load that is perpendicular to the shaft, and the thrust load is the load in the direction along the shaft. Both are permitted on the shaft during rotation, and the size of the load affects the life of the bearings.

Ambient Operating Temperature

The ambient temperature that meets the specifications, consisting of the permitted values for the external air temperature and the temperature of the parts that contact the Rotary Encoder.

Ambient Storage Temperature

The ambient temperature when the power is OFF that does not cause functional deterioration, consisting of the permitted values for the external air temperature and the temperature of the parts that contact the Rotary Encoder.

Degree of Protection

The level of protection against penetration of foreign objects from outside the Rotary Encoder. This is defined in the IEC60529 standard and expressed as IPXX.
The degree of protection against oil is specified by OMRON standards, and is expressed as oil-proof construction or oil resistance.

Absolute Code

(1) Binary Code
A pure binary code, expressed in the format 2n. Multiple bits may change when an address changes.

(2) Gray Code
A code in which only one bit changes when an address changes.
The code plate of the Rotary Encoder uses Gray Code.

(3) Remainder Gray Code
This code is used when expressing resolutions with Gray Code that are not 2n, such as 36, 360, and 720. The nature of Gray Code is such that when the most significant bit of the code changes from 0 to 1 and the same size of area is used for both the larger value and the smaller value of objects, the signal only changes by 1 bit within this range when changing from the end to the beginning of a code.
This enables any resolution that is an even number to be set with Gray Code. In this case, the code does not begin from 0, but from an intermediate code, and thus when actually using a code it must first be shifted so that it starts from 0.
The example in the code table shows 36 divisions. For the change from address 31 to 32, the code extends from address 14 to 49 when 18 addresses each are taken for the objects. When changing from address 49 to 14, only one bit changes, and we can see that the characteristic of Gray Code is preserved. By shifting the code 14 addresses, it can be converted to a code that starts from address 0.

(4) BCD
Binary Coded Decimal Code.
Each digit of a decimal number is expressed using a binary value.

Serial Transmission

In contrast to parallel transmission where multiple bits of data are simultaneously output, this method outputs data serially on a single transmission line, enabling the use of fewer wires. The receiving device converts the signals into parallel signals.

Hollow Shaft

The rotating shaft is hollow, and the drive shaft can be directly connected to the hole in the hollow shaft to reduce the length along the direction of the shaft. A leaf spring is used as a buffer to absorb vibration from the drive shaft.

Metal Disk

The rotating slit disk in the Encoder is made of metal for higher shock tolerance than glass. Due to slit machining limitations, the metal disk cannot be used for high-resolution applications.

Servo Mount

A method of mounting the Encoder in which a Servo Mounting Bracket is used to clamp down the flange of the Encoder. The position of the Encoder in the direction of rotation can be adjusted, and thus this method is used to temporarily mount the Encoder to adjust the origin. Refer to Accessories.

Absolute Code Table

DecimalBinaryGrayGray remainder 14BCD
101
0000000000000000000
1000010000010000001
2000100000110000010
3000110000100000011
4001000001100000100
5001010001110000101
6001100001010000110
7001110001000000111
8010000011000001000
9010010011010001001
10010100011110010000
11010110011100010001
12011000010100010010
13011010010110010011
1401110001001000010100
1501111001000010010101
1610000011000020010110
1710001011001030010111
18010010011011040011000
19010011011010050011001
20010100011110060100000
21010101011111070100001
22010110011101080100010
23010111011100090100011
24011000010100100100100
25011001010101110100101
26011010010111120100110
27011011010110130100111
28011100010010140101000
29011101010011150101001
30011110010001160110000
31011111010000170110001
32100000110000180110010
33100001110001190110011
34100010110011200110100
35100011110010210110101
36100100110110220110110
37100101110111230110111
38100110110101240111000
39100111110100250111001
40101000111100261000000
41101001111101271000001
42101010111111281000010
43101011111110291000011
44101100111010301000100
45101101111011311000101
46101110111001321000110
47101111111000331000111
48110000101000341001000
49110001101001351001001
501100101010111010000
511100111010101010001
521101001011101010010
531101011011111010011
541101101011011010100
551101111011001010101
561110001001001010110
571110011001011010111
581110101001111011000
591110111001101011001
601111001000101100000
611111011000111100001
621111101000011100010
631111111000001100111

Operating Procedure and Data

Peripheral Device Connectability

Incremental Encoders

Yes: Connection possible. No: Connection not possible.

Peripheral
device
Digital
Counter
Self-
powered
Tachometer
Fre-
quency/
Rate
Meter
Up/Down
Counting
Meter
Period
Meter
Direction
Detection
Unit
SYSMAC
Pulse I/O
Module *
High-
speed
Counter
Unit
EtherCAT-
compatible
Encoder
Input
Terminal
ModelH7BX-A
H7CX-A[]-N
H7BX-AW
H7CX-R[]-N
H7ER-N
K3HB-RK3HB-CK3HB-PE63-WF5CCJ2M-CPU1[]/
CPU3[]
+
CJ2M-MD21[]
C[]-CT[]GX-EC02[][]
Rotary
Encoder
model
E6D-CWZ1ENoNoNoNoNoNoNoYesNo
E6J-CWZ1E
E6D-CWZ2CYesYesYesYesYesYesNoYesNo
E6F-CWZ5GYesYesYesYesYesYesYesYesYes
E6A2-CS3E
E6A2-CW3E
E6A2-CWZ3E
YesYesYesYesYesYesNoYesNo
E6B2-CWZ3E
E6H-CWZ3E
E6C2-CWZ3E
E6C3-CWZ3EH
E6A2-CS3C
E6A2-CW3C
E6A2-CWZ3C
YesYesYesYesYesYesYesYesYes
E6A2-CS5C
E6A2-CW5C
E6B2-CWZ6C
E6H-CWZ6C
E6C2-CWZ6C
E6C3-CWZ5GH
E6B2-CWZ1XNoNoNoNoNoNoYesYesYes
E6H-CWZ3X
E6C2-CWZ1X
E6C3-CWZ3XH
E6B2-CWZ5B
E6C2-CWZ5B
NoNoYesNoYesNoNoNoNo

*Supported by CJ2M CPU Unit with unit version 2.0 or later.

Absolute Encoders

Peripheral deviceCam PositionerSYSMAC Programmable Controller
ModelH8PSCPM1ACP1HCP1LCP1EDC Input Unit
Rotary Encoder
model
E6CP-AG5CNoYesRequires separate power
supply for Encoder.
YesYesYesYesRequires separate power
supply for Encoder.
E6C3-AG5C
E6CP-AG5C-CYesNoNoNoNoNo
E6C3-AG5C-C
E6F-AG5C-C
E6F-AB3CNoYesRequires separate power
supply for Encoder.
YesYesYesYesRequires separate power
supply for Encoder.
E6F-AB3C-CNoNoNoNoNoNo

Example of Connection with H7BX-AW Self-powered Tachometer

Example of Applicable ModelsE6A2-CS3E 10P/R, 60P/R
E6C2-CWZ3E, E6F-CWZ5G 600P/R
E6C3-CWZ3EH 10P/R, 60P/R, 600P/R

Example of Connection with H7BX-A Digital Counter

Example of Applicable ModelsE6A2-CW3E
E6C2-CWZ3E, E6C3-CWZ3EH, E6F-CWZ5G

Example of Connection with K3HB-C Up/Down Counting Meter

NPN Open-collector Outputs

Example of Applicable ModelsE6A2-CS3C, E6A2-CS5C
E6A2-CW3C, E6A2-CW5C
E6C2-CWZ6C, E6F-CWZ5G

Voltage Outputs

Example of Applicable ModelsE6A2-CS3E, E6A2-CW3E
E6C2-CWZ3E

Example of Connection with CJ1W-CT021 High-speed Counter Unit in Programmable Controller

Example of Applicable Models (1)E6A2-C, E6B2-C, E6C2-C, E6H-C
E6F-CWZ5G
E6D (open-collector output)

Encoder with NPN Open-collector Output (5/12/24 VDC)

Note:Connections are as follows if the Encoder power supply is 5 V or 24 V.
Phase A + 5-V power supply ➝ A19, 24 V ➝ B20
Phase B + 5-V power supply ➝ A17, 24 V ➝ B18

Example of Applicable Models (2)E6B2-CWZ5B
E6C2-CWZ5B, E6C3-CWZ5GH

Encoder with PNP Open-collector Output (5/12/24 VDC)

Note:Connections are as follows if the Encoder power supply is 5 V or 24 V.
Phase A + 5-V power supply ➝ A19, 24 V ➝ B20
Phase B + 5-V power supply ➝ A17, 24 V ➝ B18

Example of Applicable Models (3)E6B2-CWZ1X, E6C2-CWZ1X
E6C3-CWZ3XH, E6H-CWZ3X

Encoder with Line-driver Output (RS-422)

Example of Connection with CJ2M-CPU1[]/CPU3[] + CJ2M-MD21[] SYSMAC Pulse I/O Module

Example of Applicable ModelsE6A2-CWZ5C, E6C2-CWZ6C, E6C3-CWZ5GH, E6F-CWZ5G

Up to two Pulse I/O Modules can be mounted to a CJ2M CPU Unit with unit version 2.0 or later. Each Pulse I/O Module allows you to use six inputs (IN8, IN9, IN3, IN6, IN7, and IN2) to directly input pulses from rotary encoders for application in built-in high-speed counters.

The response speed is 60 kHz for single phase and the phase difference (multiplier of 4) is 30 kHz. Counting can be performed from 0 to 4,294,967,295 pulses in incremental mode and from -2,147,483,648 to 2,147,483,647 in incremental/decremental mode.

Operating modes for the high-speed counter are set in the PLC Setup.

<Count Mode>

Phase difference input modeIncremental/decremental counting is performed using the phase difference between phases
A and B (4-times multiplier constant).
Incement/decrement pulse input modeIncremental/decremental counting is performed using phase A as the incremental pulse input
and phase B as the decremental pulse input.
Pulse and direction input modeIncremental/decremental counting is performed using phase A as the pulse input and phase
B as the direction signal (i.e., incremental/decremental).
Incremental pulse input modeIncremental counting is performed using phase A only.

<Value range mode>

Linear modeCounting is performed within the range of the upper limit and lower limit.
Ring modeCounting is performed by looping the input pulse within the set range.

<Reset Method>

Phase Z and software resetIf software reset is ON, the present value will be reset when the phase-Z input turns ON.
Software resetThe present value will be reset when software reset turns ON.

<Output Method>

Target value comparisonUp to 48 target values can be set. When the present value reaches a target value, the specified subroutine
is executed.
Range comparisonUp to 8 ranges (upper and lower limits) can be set.
When the present value enters a range, the specified subroutine is executed.
Example of Applicable ModelsE6B2-CWZ1X, E6C2-CWZ1X, E6C3-CWZ3XH, E6H-CWZ3X with Line-driver Output

Recommended Products

E6A2-C

Compact Encoder with External Diameter of 25 mm

E6B2-C

General-purpose Encoder with External Diameter of 40 mm

E6C3-A

Rugged Rotary Encoder