PLC
Name one advantage of using a PLC over relay-based control systems.
Flexibility, ease of programming, reduced wiring, or scalability (any valid answer)
What is the difference between a pressure transducer and a pressure transmitter?
A transducer converts pressure into an electrical signal, while a transmitter amplifies and conditions the signal for long-distance transmission.
What is the difference between a proportional-only controller and a PID controller?
A proportional-only controller reacts to error magnitude, while a PID controller also accounts for accumulated error (integral) and error rate (derivative).
What is the difference between stepper motors and servo motors?
Stepper motors move in discrete steps, while servo motors provide continuous motion with feedback.
What is the difference between Modbus RTU and Modbus TCP?
Modbus RTU uses serial communication, while Modbus TCP operates over Ethernet.
What does "scan time" refer to in PLC operation?
The time it takes for the PLC to execute one complete cycle of its program.
What is the purpose of a "deadband" in instrumentation?
To prevent small fluctuations in a signal from triggering a response, reducing noise or unnecessary changes.
What is "gain scheduling" in control systems?
Adjusting controller parameters dynamically based on operating conditions or system states.
What is the purpose of servo tuning?
To optimize PID parameters for precise motion control and minimize overshoot, oscillations, or lag.
What is the purpose of "handshaking" in communication protocols?
To ensure reliable data exchange between devices by confirming receipt and readiness.
What is the difference between a retentive and non-retentive timer in PLC programming?
A retentive timer retains its accumulated value after a power cycle or reset; a non-retentive timer resets its value.
What is the difference between intrinsic safety and explosion-proof design?
Intrinsic safety limits energy levels to prevent ignition, while explosion-proof design contains potential explosions within the device.
What is the purpose of a "feedforward" term in control systems?
To account for known disturbances or changes in the system before they affect the output.
What is the difference between trapezoidal and S-curve motion profiles?
Trapezoidal profiles use constant acceleration and deceleration, while S-curve profiles smooth transitions to reduce mechanical stress.
What is the purpose of an OPC server?
To facilitate communication between industrial devices and software applications.
What is the purpose of "indirect addressing" in PLC programming?
What is the purpose of "indirect addressing" in PLC programming?
What is the principle behind a piezoelectric sensor?
It generates an electrical charge in response to mechanical stress.
What is the Nyquist theorem?
The Nyquist-Shannon sampling theorem, states that to accurately reconstruct an analog signal when converting it to digital, the sampling rate must be at least twice the highest frequency component of the signal to avoid aliasing
What is the difference between linear and rotary motion control systems?
Linear systems control straight-line motion; rotary systems control rotational motion.
What is the purpose of a "gateway" in industrial communication?
To bridge different communication protocols or networks for interoperability.
What are the five standard programming languages defined by IEC 61131-3?
Ladder Diagram (LD), Function Block Diagram (FBD), Structured Text (ST), Instruction List (IL), Sequential Function Chart (SFC)
What is the principle behind a Coriolis flow meter?
It measures mass flow rate by detecting the phase shift caused by fluid motion in a vibrating tube.
What is the Laplace transform used for in control theory?
To analyze and design control systems in the frequency domain.
What is the difference between a direct-drive motor and a geared motor?
Direct-drive motors connect directly to the load for high precision, while geared motors use gear ratios to increase torque or reduce speed.
What is the difference between deterministic and non-deterministic communication protocols?
Deterministic protocols guarantee data delivery within a fixed time; non-deterministic protocols do not.