Rockwell Automation 57C422B 2 Axis Servo Module - Manual (Page 31)

PROGRAMMING 4-3
4.2 Register 0: Encoder Setup
Register 0 is used to configure the gearing reference and
feedback encoder inputs for the axis. Refer to figure 4.1.
The feedback encoder mode bits specify how the A and B
channels from the encoder will be interpreted by the module.
If the step/direction mode is selected, a high to low transition
of Channel A causes a count. If Channel B was low, the
count is incremented. If Channel B was high, the count is
decremented.
If the step + mode is selected, a high to low transition of
Channel A results in the count being incremented. A high to
low transition of Channel B results in the count being
decremented.
If the *1 quardrature is selected, only one edge of channel A
is counted. (Note that *1 quadrature is available only on B/M
57422-2C and later versions of the module.) If the *2
quadrature mode is selected, both the rising and trailing
edges of Channel A are counted. The direction is determined
from the state of Channel B.
Figure 4.1 – Encoder Configuration Register