Motion Control & Drive Systems Flashcards
7 cards from real PLC practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Motion Control & Drive Systems flashcards as text
What is the primary function of an encoder in a servo motor system?
Answer: To provide real-time position and velocity feedback to the servo controller
An encoder provides continuous position and velocity feedback to the servo controller, enabling the closed-loop control required for precise positioning applications.
What fundamentally distinguishes a servo drive from a standard VFD?
Answer: Servo drives use encoder feedback for precise closed-loop position and torque control
Servo drives utilize encoder or resolver feedback for tight closed-loop control of position, velocity, and torque, while VFDs are primarily used for open-loop or simple closed-loop speed regulation.
In PLC motion control, what does performing a 'homing' routine accomplish?
Answer: It establishes a known reference position so the controller knows the axis's absolute location
A homing routine moves the axis to a defined reference point (home position) so the motion controller establishes a coordinate origin for all subsequent absolute position moves.
A quadrature incremental encoder outputs two channels (A and B) that are 90° out of phase. What information does the phase relationship between A and B provide?
Answer: Direction of rotation (clockwise vs. counterclockwise)
The 90° phase offset between channels A and B allows the controller to determine the direction of rotation — if A leads B the motor turns one way; if B leads A it turns the other way.
What is the purpose of a 'jog' command in a PLC motion control application?
Answer: Move the axis continuously at a slow speed only while the command signal is held active
A jog command moves the axis at a controlled, low speed only while the discrete input or button is held active, allowing operators to manually position equipment during setup or maintenance.
What is the function of a 'torque limit' parameter in a servo drive configuration?
Answer: It caps the maximum force the servo can apply, protecting mechanical components from overload
A torque limit prevents the servo drive from commanding more torque than the mechanical system can safely handle, protecting gearboxes, tooling, and workpieces from damage during unexpected obstructions.
According to PLCopen motion control standards, which function block commands an axis to move to a specified absolute position?
Answer: MC_MoveAbsolute
MC_MoveAbsolute is the PLCopen-standard function block that commands an axis to travel to a specified absolute coordinate at a defined velocity and acceleration.