ADLINK PCI-8154 - Manual (Page 79)

Operation Theory 69
4.3.2 Pulse feedback input interface
Our motion controller provides one 28-bit up/down counter of each
axis for pulse feedback counting. This counter is called position
counter. The position counter counts pulses from the EA and EB
signal which have plus and minus pins on connector for differential
signal inputs. It accepts two kinds of pulse types. One is dual
pulses input (CW/CCW mode) and the other is AB phase input.
The AB phase input can be multiplied by 1, 2 or 4. Multiply by 4 AB
phase mode is the most commonly used in incremental encoder
inputs.
For example, if a rotary encoder has 2000 pulses per rotation,
then the counter value read from the position counter will be 8000
pulses per rotation when the AB phase is multiplied by four.
If users don’t use encoder for motion controller, the feedback
source for this counter must be set as pulse command output or
the counter value will always be zero. If it is set as pulse command
output, users can get the position counter value from pulse com-
mand output counter because the feedback pulses are internal
counted from command output pulses.
The following diagrams show these two types of pulse feedback
signal.