ADLINK PCI-9524 - Manual (Page 84)

68 Operation Theory
PCI-9524 ADLINK Technology Inc.
User’s Manual Copyright 2008
Encoders using open-drain/open-collector output stages can gen-
erally go as high as 500-kHz pulses per second. For higher speed
applications, use encoders with differential line-driver output
stages. To ensure low EMI leakage, use twisted pair cabling for
high-speed differential signal transmissions.
PCI-9524 uses quadrature decoding logic, or X4 encoder mode,
that increments/decrements the counter value on every edge of
either Phase A or Phase B waveform. This provides four times the
resolution of angular/linear displacement, as shown in Figure 4-8.
Figure 4-8: X4 Encoder mode
The decoder has a built-in position comparator that generates an
AD trigger signal whenever the count value matches the user
specified one.
The PCI-9524 has an internal power supply for powering the
external encoders and their output stages. The default output volt-
age is 5V. For applications requiring 12V output, please consult
ADLINK technical support or Field Application Engineers (FAE).
For encoders that require currents exceeding the capacity of the
internal power supply, an external power supply is required. If
needed, connect its power ground to isolated ground (ISOGND)
on PCI-9524.