Connect to Digital Quadrature Encoders
Encoder Wiring
Connect to Differential Encoders
Connect to differential encoders
(digital).
Connect to Single-ended Encoders
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Note
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To
connect the RMB's differential line receivers to single-ended encoders,
you must add a pair of resistors (R1, R2) in the configuration shown,
to bias the negative end to the middle of the encoder's output voltage
range.
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Connect to single-ended encoders
(digital).
Broken Wire and Illegal State
Detection
The encoder inputs (channel A+, A-, B+, B-) are monitored by the FPGA
(an on-board logic component). The encoder inputs are sampled at 25MHz.
By default, a digital filter is applied to each encoder input. This digital
filter requires that an encoder input (channel A+, A-, B+, B-) be stable
for 4 clock cycles (160 nanoseconds) before a transition is recognized,
i.e., encoder input states lasting less than 4 clock cycles are filtered
out. This means that the absolute maximum encoder rate is 12.5 million counts/sec
with digital filtering enabled.
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