Copley Controls 7228AC, User Manual

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7XX8 Series Digital Servo Amplifier User Guide
2-11
There are several ways to configure the encoder
interface. However, differential signals are
recommended for their inherently large CMRR (common
mode noise rejection ratio). For more information about
encoder formats see Chapter 3.
Phase A
Index
Phase B
Figure 2-6 Quadrature Encoder Pulses
Encoder Receiver Encoder Receiver
Encoder Receiver Encoder Receiver
Encoder Receiver
The same encoder receiver circuit (Figure 2-7) is used
to receive the quadrature encoder pulses: phase A,
phase B, and index. This circuit is designed to work with
differential signals (Figure 2-8), single-ended TTL
signals and open collector circuits (Figure 2-9).
Receiver circuit
same for all encoder inputs
2.2k
1k
47pF
+5V
1k
47pF
Copley Driver
26LS32
Figure 2-7 Encoder Receiver Circuirt
A,B,X
/A, /B, /X