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Ndrive HL User’s Manual
Glossary of Terms
www.aerotech.com A-5
Limits
Sensors called limits that alert the control electronics that the
physical end of travel is being approached and motion should
stop.
Linear Motor
A motor consisting of 2 parts, typically a moving coil and
stationary magnet track. When driven with a standard servo
amplifier, it creates a thrust force along the longitudinal axis of
the magnet track.
Load Carrying Capability
The maximum recommended payload that does not degrade the
listed specifications for a mechanical stage.
Master-Slave
Type of coordinated motion control where the master axis
position is used to generate one or more slave axis position
commands.
MMI
Man Machine Interface used as a means of getting operator
data into the system. (See HMI)
Motion Profile
A method of describing a process in terms of velocity, time, and
position.
Motor Brush
The conductive element in a DC brush-type motor used to
transfer current to the internal windings.
Motor, Brushless
Type of direct current motor that utilizes electronic commutation
rather than brushes to transfer current.
Motor, Stepping
Specialized motor that allows discrete positioning without
feedback. Used for non-critical, low power applications, since
positional information is easily lost if acceleration or velocity
limits are exceeded.
NC
Numerical Control. Automated equipment or process used for
contouring or positioning. (See CNC). Also, a Normally-Closed
switch.
NO
A Normally-Open switch.
NEMA
National Electrical Manufacturer’s Association. Sets standards
for motors and other industrial electrical equipment.
Non-Volatile Memory
Memory in a system that maintains information when power is
removed.
Open Collector
A signal output that is performed with a transistor. Open
collector output acts like a switch closure with one end of the
switch at circuit common potential and the other end of the
switch accessible.
Open Loop
Control circuit that has an input signal only, and thus cannot
make any corrections based on external influences.
Operator Interface
Device that allows the operator to communicate with a machine.
A keyboard or thumbwheel is used to enter instructions into a
machine. (See HMI or MMI)
Optical Encoder
A linear or angular position feedback device using light fringes to
develop position information.
Opto-Isolated
System or circuit that transmits signal with no direct electrical
connections, using photoelectric coupling between elements.
Orthogonality
The condition of a surface or axis perpendicular (offset 90°) to a
second surface or axis. Orthogonality specification refers to the
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