User Manual

Connecting Sensors and Actuators to Input/Outputs
56 Advanced Digital Motor Controller User Manual V2.0, July 8, 2019
Connecting the SSI Sensor
SSI Sensors connect directly to pins present on the controller’s connector. The connector
provides 5V power to the sensors and has inputs for the two data and the two clock sig-
nals for each sensor. The figure below shows the connection to the SSI Sensor.
FIGURE 3-16. Controller Connection to typical SSI Encoder
Connecting Optical Encoders
Optical Incremental Encoders Overview
Optical incremental encoders are a means for capturing speed and traveled distance on a
motor. Unlike absolute encoders which give out a multi-bit number (depending on the res-
olution), incremental encoders output pulses as they rotate. Counting the pulses tells the
application how many revolutions, or fractions of, the motor has turned. Rotation velocity
can be determined from the time interval between pulses or by the number of pulses
within a given time period. Because they are digital devices, incremental encoders will
measure distance and speed with perfect accuracy.
Since motors can move in forward and reverse directions, it is necessary to differentiate
the manner that pulses are counted so that they can increment or decrement a position
counter in the application. Quadrature encoders have dual channels, A and B, which are
electrically phased 90° apart. Thus, the direction of rotation can be determined by monitor-
ing the phase relationship between the two channels. In addition, with a dual-channel en-
coder, a four-time multiplication of resolution is achieved by counting the rising and falling
edges of each channel (A and B). For example, an encoder that produces 250 Pulses per
Revolution (PPR) can generate 1,000 Counts per Revolution (CPR) after quadrature.
1 Pulse
= 4 Transitions
= 4 Counts
A Channel
Count Up
Count Down
B Channel
Quadrature
Signal
FIGURE 3-17. Quadrature encoder output waveform