Quadrature encoder fundamentals, Quadrature, S quadrature – Delta RMC151 User Manual
Page 212: Be quadrature encoder
RMC70/150 and RMCTools User Manual
RMC70
AA1
-10 to +10V, 4-20mA
-10 to +10V, 4-20mA
-10 to +10V, 4-20mA
-10 to +10V, 4-20mA
RMC150
Analog (H)
-10 to +10V, -5 to +5V, 4-20mA
-10 to +10V
-10 to +10V, -5 to +5V, 4-20mA
-10 to +10V, 4-20mA
Analog Outputs
All the Axis Modules have one analog ±10V Control Output. See the Control Output topic
for details.
3.12.4. Quadrature Encoder Fundamentals
Quadrature encoders are one of the most common types of encoders. Quadrature encoders
are incremental, meaning that they can accurately measure changes in position, but cannot
provide an absolute position.
Quadrature encoders are often used on motors. They are also commonly used to provide a
reference input, such as the position of a belt, or the position of a board on a flying cut-off
application.
Quadrature feedback is supported by the following modules:
RMC70: QA axis module, Q1 expansion module
RMC150: Quadrature (Q) module, Universal I/O module
The RMCs require an RS-422 quadrature signal. This is also commonly referred to as a 5V
differential signal. The RMCs do not support single-ended quadrature signals.
Operation
A and B Signals
Quadrature encoders use two output channels (A and B) to indicate position. Using two
code tracks with sectors positioned 90 degrees out of phase, the two output channels of
the quadrature encoder indicate both position and direction of rotation. If A leads B, for
example, the disk is rotating in a clockwise direction. If B leads A, then the disk is
rotating in a counter-clockwise direction.
By monitoring both the number of pulses and the relative phase of signals A and B, both
the position and direction of rotation can be tracked.
The resolution of quadrature encoders is typically given in Pulses per Revolution (PPR),
also called Lines per Revolution. The RMC feedback sees each rising or falling edge of the
A or B signal as one count. Therefore, each pulse or line of the encoder will result in four
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