Operating instructions

Principles of Rotary Encoders
15
Pepperl+Fuchs Inc. • 1600 Enterprise Parkway • Twinsburg, Ohio 44087-2245 • www.am.pepperl-fuchs.com
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PEPPERL+FUCHS
Interfaces
Line Driver (RS-422)
This symmetrical interface is recommended for use whenever
a longer cable length is required. The corresponding core pairs
must be twisted for maximum interference resistance.
This interface can also be used as a replacement for the TTL
interface. In this case, the inverted outputs are not used.
Push-Pull Output
The push-pull output is a combination of NPN and PNP
outputs. Compared to open collector outputs, the push-
pull output features an improved square wave. In addition,
interference resistance is improved. No external wiring is
required as in NPN or PNP outputs. Push-pull also offers
inverted channels. The main applications of push-pull are
within the range of median switching frequencies. The open
collector outputs can be replaced by push-pull by using only
the non-inverted outputs.
NOTE: By linking channels A and B, rotation direction
data is lost.
Relationship Between Speed and Output
Frequency
A
B
x 2
A
B
x 4
Doubling of signals
Quadrupling of signals
2,0001,000 3,000 4,000 5,0000
1,000
2,000
3,000
4,000
5,000
6,000
7,000
0
8,000
9,000
10,000
f = 150 kHz
f = 100 kHz
f = 50 kHz
f = 25 kHz
z [pulses per revolution]
f = x Z (n in rpm)
n
max
= (f
max
in Hz, n
max
in rpm)
n
60 s
n
max
x 60 s
Z
n
max
[rpm]
A
B
Z
PLC
A
0
Z
B
B
A
R
R
R
Encoder Control unit exampl
e
Encoder Control unit exampl
e
0
B
A
0
B
A