ADLINK PCI-8154 - Manual (Page 80)

70 Operation Theory
Plus and Minus Pulses Input Mode (CW/CCW Mode)
The pattern of pulses in this mode is the same as the Dual Pulse
Output Mode in the Pulse Command Output section except that
the input pins are EA and EB.
In this mode, pulses from EA pin cause the counter to count up,
whereas EB pin caused the counter to count down.
90° phase difference signals Input Mode (AB phase Mode)
In this mode, the EA signal is a 90° phase leading or lagging in
comparison with the EB signal. “Lead” or “lag” of phase difference
between two signals is caused by the turning direction of the
motor. The up/down counter counts up when the phase of EA sig-
nal leads the phase of EB signal.
The following diagram shows the waveform.
The index input (EZ) signal is as the zero reference in linear or
rotary encoder. The EZ can be used to define the mechanical zero
position of the mechanism. The logic of signal must also be set
correctly to get correct result.