Control Techniques SM-Encoder Output Plus, Руководство пользователя

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14
SM-Encoder Plus & SM-Encoder Output Plus User Guide
www.controltechniques.com Issue: 4
Figure 4-6 Encoder galvanically isolated from encoder body
4.3.3 No isolation
As shown in Figure 4-7 the encoder 0V connection may be permanently connected to
the housing. This has the advantage that the encoder body can form a shield for its
internal circuits. However it permits noise current from the motor body to flow into the
encoder cable shield. A good quality shielded cable correctly terminated protects the
data against this noise current, but much more care is needed in ensuring correct cable
management than for the isolated cases.
Figure 4-7 No isolation
Motor
Shaft
Motor
Housing
Encoder
Housing
No Isolation
between motor housing
and encoder housing
No Isolation
between motor shaft
and encoder
Encoder
Connection
Stray
Capacitance
Encoder
Body
Encoder
Circuit
0V
+5V
0V
+5V
0V
+5V
B
B
Z
Z
A
A
Galvanic
Isolation
0V
+5V
0V
+5V
0V
+5V
B
B
Z
Z
A
A
Motor
Shaft
Motor
Housing
Encoder
Housing
No Isolation
between motor housing
and encoder housing
No Isolation
between motor shaft
and encoder
Encoder
Connection
Stray
Capacitance
Encoder
Body
Encoder
Circuit
0V
connected
to encoder
housing