10+ Control Engineer Interview Questions and Answers

TON activates after a set time delay; TOF deactivates after a set time delay once the input goes low.

• TON (On Delay Timer) starts timing when the input is activated and outputs after the preset time.

• Example of TON: A motor starts after a 5-second delay when a start button is pressed.

• TOF (Off Delay Timer) starts timing when the input is deactivated and outputs until the preset time elapses.

• Example of TOF: A light remains on for 10 seconds after a switch is turned off.

Communication networking systems are used to connect devices and share information in automation, with differences in protocols, speed, and reliability.

• Communication networking systems in automation include Ethernet, Profibus, Modbus, and DeviceNet.

• Ethernet is commonly used for high-speed communication between devices in industrial automation.

• Profibus is a fieldbus communication protocol used for connecting field devices in automation systems.

• Modbus is a serial communication ...read more

I/O modules in a PLC facilitate communication between the controller and field devices, enabling data exchange and control.

• Connects PLC to external devices like sensors and actuators.

• Converts signals from field devices into a format the PLC can process.

• Examples include digital input modules for switches and digital output modules for relays.

• Analog I/O modules handle continuous signals, such as temperature or pressure readings.

• Provides isolation between the PLC and field devic...read more

PLC principles include automation, input/output control, programming languages, and reliability in industrial applications.

• Modular design: PLCs can be expanded with additional I/O modules for flexibility.

• Input/Output (I/O) operations: PLCs read inputs from sensors and control outputs to actuators.

• Programming languages: Common languages include Ladder Logic, Function Block Diagram, and Structured Text.

• Real-time operation: PLCs execute control tasks in real-time, ensuring timel...read more

Timers and counters in Ladder Logic control operations based on time and event counts, enhancing automation processes.

• Timers are used to delay actions or create time-based events. Example: TON (Timer ON Delay) starts timing when the input is true.

• Counters track the number of occurrences of an event. Example: CTU (Count Up) increments the count each time the input is true.

• Timers can be reset using a reset instruction, while counters can be reset to zero or a preset value.

• Diffe...read more

Basic instruments for measurement include rulers, thermometers, scales, timers, and gauges.

• Rulers for measuring length or distance

• Thermometers for measuring temperature

• Scales for measuring weight or mass

• Timers for measuring time

• Gauges for measuring pressure, flow, or level

• Examples: tape measure, mercury thermometer, kitchen scale, stopwatch, tire pressure gauge

I have extensive experience in controller design for various systems and industries.

• I have designed controllers for industrial automation systems, such as PLCs and SCADA systems.

• I have experience in designing feedback control systems using PID algorithms.

• I have worked on controller design for motion control systems, such as robotics and CNC machines.

• I have designed controllers for power electronics systems, such as inverters and motor drives.

• I have experience in tuning contro...read more

A PLC (Programmable Logic Controller) is an industrial digital computer used for automation of electromechanical processes.

• PLCs are designed to handle multiple inputs and outputs, making them suitable for complex control tasks.

• They operate using a scan cycle: input scan, program execution, and output scan.

• Common applications include assembly lines, robotic devices, and traffic light control systems.

• PLCs can be programmed using ladder logic, function block diagrams, or structu...read more

Ladder Logic is a graphical programming language used for PLCs, resembling electrical relay logic diagrams.

• Basic components include rungs, contacts, and coils.

• Rungs represent control logic, similar to a ladder's steps.

• Contacts can be normally open (NO) or normally closed (NC), controlling the flow of current.

• Coils represent outputs, such as motors or lights, activated by the logic in the rungs.

• Example: A rung with a NO contact and a coil will activate the coil when the contac...read more

A star-delta starter is an electrical motor starting device that reduces the starting current and torque of the motor.

• It consists of a contactor, overload relay, and timer.

• During starting, the motor is connected in star configuration to reduce the voltage across each winding.

• After a set time, the motor is switched to delta configuration for normal operation.

• It is used for large motors to prevent damage to the motor and power supply.

• It is commonly used in industries such as oi...read more