692
Rotary Encoders
4
Rotary Encoders,
Absolute Rotary Encoders,
Standard
4
.1.1
Rotary Encoders,
Absolute Rotary Encoders
for hazardous areas
4
.1.3
Rotary Encoders,
Absolute Rotary Encoders
for safety applications
4
.1.2
Rotary Encoders,
Incremental Rotary Encoders
with pulse outputs
4
.2.1
Rotary Encoders,
Incremental Rotary Encoders,
Sine/Cosine
4
.2.2
Rotary Encoders,
Incremental Rotary Encoders
for hazardous areas
4
.2.4
Rotary Encoders,
Incremental Rotary Encoders
for safety applications
4
.2.3
Rotary Encoders,
Safety Speed Monitor
4
.5
Rotary Encoders,
Cable pulls
4
.3
Rotary Encoders,
Accessories
4
.4
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Consider the General Notes on the Information in the Pepperl+Fuchs Product Catalogs
Pepperl+Fuchs Group
fa-info@de.pepperl-fuchs.com
USA: +1 330 486 0001
fa-info@us.pepperl-fuchs.com
Singapore: +65 6779 9091
fa-info@sg.pepperl-fuchs.com
Copyright Pepperl+Fuchs
Application Notes for Incremental Rotary
Encoders
Incremental rotary encoders are rotary encoders that only emit pulses.
The angular position can be calculated from the resolution (Z) and the
number of pulses per revolution. The angular speed (w) can be calcu-
lated from the signal frequency.The period duration of the angular accel-
eration (a) can also be calculated from the temporal change.
Rotational direction monitoring with incremental
rotary encoders
To detect the direction of rotation of a movement, the detection principle
is extended to include a receiver on channel A and channel B. Rotational
direction monitoring is enabled by the 90° phase-shifted detection (see
graphic).
In the first graphic (l cw), channel A runs ahead of channel B. This in-
dicates clockwise rotation, whereas II ccw indicates counter-clockwise
rotation. The direction of rotation is specified on the rotary encoder shaft
from the perspective of the viewer.
Depending on the type of incremental rotary encoder, channel A or chan-
nel B is the lead channel. Further details are included in the respective
data sheets.
A
B
A
B
90
˚
I cw
II ccw
Zero signal
The actual measurement or, more precisely, the evaluation (counting) of
the pulses takes place in an additional control interface.This could be, for
example, a counter, a control device (PLC), or a tachometer.
If detection should not be limited to within one revolution, a further signal
is required that appears only once per revolution. This signal (third chan-
nel) is known as a zero signal, channel N, or spur N. The zero signal is
often also used as the reference value.
The graphic illustrates the signal sequence of a three-channel incremen-
tal rotary encoder.
A
B
0
Inverted channels
The inverted signals are used in addition to spurs A, B, and 0 to improve
signal transmission. This transmission is available as an option with the
RS422 standard interface and with push-pull.
A
A
B
B
0
0
The advantage is that unwanted signals can be blanked. If a noise pulse
occurs, it is induced equally in all lines if the strands are twisted in pairs.
The noise pulse can be blanked by calculating the difference. The work-
ing principle is illustrated in the graphic below.
5
V
A
0
V
5
V
0
V A
A
5
V
0
V
Pulse multiplication
Pulse multiplication is used to increase the measuring steps or reduce
the output frequency of the incremental rotary encoder.The signals of an
incremental rotary encoder can be doubled or multiplied by linking chan-
nels A and B (see following graphics).
Example:
An application requires 20,000 measuring steps per revolution at a speed
of 3000 min -1 . If the control units (PLC, counter, tachometer) offer the
"
multiplication" option, it is possible to revert to the more cost-effective
incremental rotary encoders with 5000 pulses. The output frequency of
the incremental rotary encoder is also reduced.
•
Without multiplication: 1 MHz (this frequency is too high for most
control units)
•
With multiplication: 250 kHz
A
B
x 2
.
Signal doubling
Fault
Signal line
Inverted
signal
line
Interference-free
signal
Rotary Encoders
