PLC Interviews | Important Questions | Preparation Guide #plc #interview #2024
Welcome back to 'IT and Automation Academy .If you're not sure what to prepare for an interview for a PLC or Control Engineer role, you're in the right place! This video will help you cover the most important questions to ace any automation interview, especially for a PLC role.
Before we dive into the content, if you're new to our channel, do consider subscribing and turning on notifications to stay updated on our future content. Now, let's get into the interview preparation. Our initial question is
What is a PLC?
A Programmable Logic Controller (PLC) is a specialized digital computer used for automation of industrial processes, such as controlling machinery on factory assembly lines, amusement rides, or lighting fixtures.
2nd Question is What are the key components of a PLC?
The main components of a PLC include the CPU (Central Processing Unit), input and output modules, programming device, and memory.
3rd Question is Explain the working principle of a PLC.
PLCs receive inputs from sensors or other devices, process these inputs based on a programmed logic, and then produce outputs to control actuators or other devices. The program is typically created using ladder logic or other programming languages.
4th Question is What is ladder logic?
Ladder Logic is a programming language commonly used in PLCs. It resembles relay logic diagrams and consists of rungs with contacts and coils, representing input conditions and output actions, respectively.
Next question is Differentiate between analog and digital inputs/outputs in PLCs.
Digital inputs/outputs deal with discrete on/off signals (binary), while analog inputs/outputs handle continuous signals within a range, such as voltage or current.
Next question is Explain the scan cycle of a PLC.
The scan cycle of a PLC involves scanning inputs, executing the program logic, and updating outputs. It typically includes three stages: input scan, program scan, and output scan.
What is the difference between sinking and sourcing in PLCs?
Sinking and Sourcing refer to the way a PLC handles the current flow in its input or output circuits. In sinking configuration, the current flows from the devices to the PLC, while in sourcing configuration, the current flows from the PLC to the devices.
What is PID control in PLC?
PID (Proportional, Integral, Derivative) control is a method used in PLCs for closed-loop control systems. It helps maintain a process variable at a desired setpoint by adjusting the output based on proportional, integral, and derivative terms.
Explain the concept of ladder logic timers and counters.
Timers and counters in ladder logic are used to control time and count events, respectively. Timers are used to introduce delays or time-based operations, while counters keep track of events or occurrences.
How do you troubleshoot a PLC program?
Troubleshooting involves checking the program logic, inspecting input and output devices, reviewing wiring connections, and using monitoring tools provided by the PLC software. Debugging tools and simulation features can also be helpful.