UMI Accessory User Guide — UMI-4A
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The UMI-4A accessory allows for differential inputs for Phase A, Phase B,
and Index signals. You can easily accommodate encoders with phase
relationships different from Figure 18 by swapping the signals as required
by the specific application. The Index pulse must occur when both Phase A
and Phase B signals are logic low as shown in Figure 7. Servo and
closed-loop stepper applications require encoder feedback and consistent
directional polarity between the motor and encoder for stable operation.
The UMI-4A uses the following standards for motor direction:
•
Positive = forward = Clockwise (CW) facing motor shaft
•
Negative = reverse = Counter-clockwise (CCW) facing motor shaft
Figure 18.
Encoder Signal Phasing—CW Rotation
The encoder inputs are filtered by both analog and digital noise filters. You
must use cables with twisted pairs and an overall shield for improved noise
immunity. When connecting the encoder to the UMI-4A, you should use at
least 24-AWG wire.
Caution
Using an unshielded cable allows noise to corrupt the encoder signals, which
results in lost counts, reduced accuracy, and other erroneous encoder and controller
operations.
Limit Switch Terminal Block
For forward and reverse limit and home switch connections, each UMI-4A
has a separate 6-position terminal block per axis. All limit and home switch
inputs are filtered on the UMI-4A to enhance noise immunity.
The UMI-4A supports active and passive limit switches. You can use
auxiliary VDC on pin 4 to power active, open-collector limit switches. To
use the auxiliary VDC you must supply a voltage to the auxiliary VDC
input (pin 2 of the power input terminal block). Refer to Figure 12 to help
you locate the limit switch terminal block on your UMI-4A accessory.
Figure 19 shows an example of a passive limit switch terminal block
pinout.
Phase A
Phase B
Index
Summary of Contents for UMI-4A
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