Aerotech BM Series, Hardware Manual

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Appendix A BM/BMS Series Hardware Manual
A-6 www.aerotech.com
PWM
Pulse Width Modulation. Switch-mode technique used in
amplifiers and drivers to control motor current. The output
voltage is constant and switched at the bus value (160 VDC with
a 115 VAC input line).
Quadrature
Refers to the property of position transducers that allows them to
detect direction of motion using the phase relationship of two
signal channels. A 1000-line encoder will yield 4000 counts via
quadrature.
Radial Runout
Positioning error of the rotary stage in the horizontal direction
when the tabletop is oriented in the horizontal plane. Radial
runout is defined as the total indicator reading on a spherical ball
positioned 50 mm above the tabletop and centered on the axis
of rotation.
Ramp Time
Time it takes to accelerate from one velocity to another.
Range
The maximum allowable travel of a positioning stage.
RDC
Resolver to Digital Converter. Electronic component that
converts the analog signals from a resolver (transmitter type)
into a digital word representing angular position.
Repeatability
The maximum deviation from the mean (each side) when
repeatedly approaching a position. Unidirectional repeatability
refers to the value established by moving toward a position in
the same direction. Bidirectional repeatability refers to the value
established by moving toward a position in the same or opposite
direction.
Resolution
The smallest change in distance that a device can measure.
Retroreflector
An optical element with the property that an input light beam is
reflected and returns along the same angle as the input beam.
Used with laser interferometers.
Roll (of travel)
Angular motion of a carriage around an axis parallel to the
motion direction and perpendicular to the yaw axis.
Roll Error
Positioning error resulting from a roll motion.
Rotor
The rotating part of a magnetic structure. In a motor, the rotor is
connected to the motor shaft.
RS-232C
Industry standard for sending signals utilizing a single-ended
driver/receiver circuit. As such, the maximum distance is limited
based on the baud rate setting but is typically 50-100 feet. This
standard defines pin assignments, handshaking, and signal
levels for receiving and sending devices.
RS-274
Industry standard programming language. Also referred to as G-
code machine programming. A command set specific for the
machine tool industry that defines geometric moves.
RS-422
Industry communication standard for sending signals over
distances up to 4000 feet. Standard line driver encoder
interfaces utilize RS-422 because of the noise immunity.
Runout
The deviation from the desired form of a surface during full
rotation (360 degrees) about an axis. Runout is measured as
total indicated reading (TIR). For a rotary stage, axis runout
refers to the deviation of the axis of rotation from the theoretical
axis of rotation.
Servo System
Refers to a closed loop control system where a command is
issued for a change in position and the change is then verified