400+ Automation Engineer Interview Questions and Answers

Modbus is a communication protocol used in industrial automation. It allows communication between devices connected to a network.

• Modbus is used to transmit data between devices in a master-slave architecture.

• There are two types of Modbus: Modbus RTU (serial communication) and Modbus TCP (Ethernet communication).

• Modbus RTU supports up to 247 slaves while Modbus TCP can support thousands of slaves.

• Modbus is commonly used in industries such as manufacturing, oil and gas, and ene...read more

The interview questions cover OOP concepts, coding exercises, project frameworks, Selenium automation, BDD with Cucumber, and TestNG.

• OOP concepts include inheritance, encapsulation, polymorphism, and abstraction.

• Example: Inheritance - a class 'Car' can inherit properties from a class 'Vehicle'.

• To find missing number in a list, iterate through the list and check for gaps in sequence.

• Example: List {1, 2, 4, 5} - Missing number is 3.

• To count alphabets in a string, iterate throug...read more

Absolute Xpath is the complete path from the root element to the desired element, while Relative Xpath is the path based on the current element.

• Absolute Xpath starts with a single slash (/) and is more specific but less flexible.

• Relative Xpath starts with a double slash (//) and is more flexible but less specific.

• Absolute Xpath is more prone to breaking if the structure of the page changes.

• Relative Xpath is easier to maintain and update as it is based on the element's positio...read more

ASI protocol is a serial communication protocol used in industrial automation systems.

• ASI stands for Actuator Sensor Interface.

• It is used to connect sensors and actuators to a central controller.

• It is a simple and cost-effective protocol.

• It supports up to 62 slaves per master.

• It uses a 2-wire bus for communication.

There are various types of PLCs with different communication protocols.

• PLC types include Programmable Logic Controller, Compact Programmable Logic Controller, Modular Programmable Logic Controller, and more.

• Communication protocols include Modbus, Profibus, DeviceNet, Ethernet/IP, and more.

• The type of PLC and communication protocol used depends on the specific automation application.

• PLCs can communicate with other devices such as sensors, actuators, and HMIs using different pr...read more

Watchdog timer is a safety mechanism that resets the system if it fails to respond within a set time. System overhead time is the time required for the system to perform non-critical tasks. RPI is the rate at which the PLC scans its inputs and outputs.

• Watchdog timer is used to prevent system failures due to software or hardware issues

• System overhead time is the time required for the system to perform non-critical tasks such as updating the clock or handling interrupts

• RPI is t...read more

RS Linx is a software used for communication between Rockwell Automation devices. It includes drivers and FactoryTalk Linx.

• RS Linx is a communication software used for Rockwell Automation devices

• It includes drivers for various devices such as PLCs, HMIs, and drives

• FactoryTalk Linx is a component of RS Linx that allows communication between devices and software applications

• RS Linx supports various communication protocols such as Ethernet/IP, ControlNet, and DeviceNet

driver.navigate() loads a new web page while driver.get() loads a web page for the first time.

• driver.get() loads a web page for the first time

• driver.navigate() loads a new web page without closing the current one

• driver.navigate() can also go back and forward in the browser history

• driver.get() and driver.navigate() both accept a URL as a parameter

Code using multithreading to scan 3 log files for different patterns and write matches in o/p file with low memory footprint.

• Use Python's threading module to create multiple threads for each log file

• Use regex to search for patterns in each log file

• Write matches to output file using a thread-safe queue

• Use a memory-efficient data structure like deque to store log file lines

Standard HMI for basic operations, Performance HMI for complex operations.

• Standard HMI for simple and routine operations

• Performance HMI for complex and critical operations

• Performance HMI for high-speed processes

• Standard HMI for low-speed processes

The Micrologix 1400 can support up to 6 types of analog signals.

• The Micrologix 1400 can handle analog signals such as voltage, current, resistance, thermocouples, RTDs, and potentiometers.

• It has 6 analog inputs that can be configured for different types of signals.

• For example, you can use one input for a voltage signal and another input for a thermocouple signal.

• The analog signals can be used for monitoring and controlling various processes in automation.

• The Micrologix 1400 a...read more

Kepware is a software solution for industrial automation communication.

• Kepware is used to connect different industrial devices and software applications.

• It supports various communication protocols such as OPC DA, OPC UA, MQTT, etc.

• OPC DA is a legacy protocol used for communication between Windows-based applications and process control hardware.

• OPC UA is a newer and more secure protocol that supports cross-platform communication and data modeling.

• Kepware provides a user-friend...read more

The code demonstrates static variable behavior in Java with class inheritance and method invocation.

• Static variables belong to the class, not instances. Here, 'i' is shared across all instances of class A.

• When 'a.inc()' is called, 'i' increments from 10 to 11, then to 12.

• Class B is not defined in the code, leading to a compilation error.

• If class B extends A, 'b.inc()' would also affect 'i', continuing from the last value.

Effective data cleaning involves identifying and correcting errors in a dataset to ensure accuracy and reliability.

• Identify and remove duplicate entries

• Correct inaccuracies and inconsistencies in data

• Handle missing values appropriately

• Standardize data formats and values

• Validate data against predefined rules or constraints

• Automate the process using scripts or tools like Python pandas or SQL queries

Types of XPaths in Selenium include Absolute XPath, Relative XPath, and Custom XPath.

• Absolute XPath: Specifies the complete path from the root element to the desired element.

• Relative XPath: Specifies the path to the desired element based on its relationship with other elements.

• Custom XPath: Allows for more flexibility and specificity in locating elements using various attributes and functions.

Documents needed for Commissioning/Servicing as an Automation Engineer

• Equipment manuals and specifications

• Commissioning checklists

• Service and maintenance procedures

• Schematics and wiring diagrams

• Troubleshooting guides

• Safety guidelines and protocols

2D refers to two-dimensional objects or images, while 3D refers to three-dimensional objects or images.

• 2D objects have length and width, while 3D objects have length, width, and depth

• 2D images are flat, while 3D images have depth and can be viewed from different angles

• 2D objects can be represented on a piece of paper or screen, while 3D objects require special software or equipment to view

• Examples of 2D objects include drawings, photographs, and paintings, while examples of 3...read more

There are several types of 4-20 mA type transmitters used in automation engineering.

• Some common types include pressure transmitters, temperature transmitters, level transmitters, and flow transmitters.

• Each type of transmitter is designed to measure a specific parameter and convert it into a 4-20 mA current signal.

• For example, a pressure transmitter measures the pressure of a fluid or gas and converts it into a 4-20 mA signal.

• Similarly, a temperature transmitter measures the t...read more

The output of the code will be 'animal is created' followed by 'Dog is created'.

• The code defines a class Animal with a constructor that prints 'animal is created'.

• It also defines a class Dog that extends Animal, with a constructor that prints 'Dog is created'.

• In the main method, an instance of Dog is created, which will trigger the constructors of both Animal and Dog classes.

Simulating one user profile to another can be done through user impersonation.

• User impersonation can be achieved through various tools and techniques.

• One way is to use a proxy server to intercept and modify the user's requests and responses.

• Another way is to use a browser extension or plugin that allows you to switch between user profiles.

• You can also use a testing tool like Selenium to automate the process of switching between user profiles.

• It's important to ensure that the ...read more

Code to run as a service to scan CPU/memory every 30 sec and calculate min, max, avg and moving avg of last 300 sec.

• Use a loop to run the code every 30 sec

• Use psutil library to get CPU/memory usage

• Store the values in a list and calculate min, max, avg and moving avg using numpy library

• Use threading to run the code in the background as a service

The ports in my current project are utilized for communication between different devices and systems.

• Ports are used to establish connections and transfer data between devices.

• They can be physical ports, such as USB or Ethernet ports, or virtual ports.

• In my project, we use ports to connect sensors, actuators, and controllers to the automation system.

• For example, we have a temperature sensor connected to a port on a PLC (Programmable Logic Controller) to monitor the temperature...read more

Multiprocessing is the use of multiple processors to execute multiple tasks simultaneously. Multithreading is the use of multiple threads within a single process to execute multiple tasks simultaneously.

• Multiprocessing involves the use of multiple processors or cores to execute multiple tasks simultaneously.

• Multithreading involves the use of multiple threads within a single process to execute multiple tasks simultaneously.

• Multiprocessing is typically used for CPU-intensive ta...read more

Answers to common interview questions for Automation Engineer

• POJO class is a plain old java object used to represent data

• throw is used to throw an exception while throws is used to declare an exception

• To run tests parallelly in TestNG, use the 'parallel' attribute in the test tag

• final is used to declare a constant variable while Finally is used to execute a block of code after try-catch

• To validate response in rest api, use assertions to check the expected response

• To store res...read more

I have consistently delivered exceptional results and have successfully implemented automation solutions that have significantly improved efficiency and productivity.

• I have a proven track record of successfully implementing automation solutions.

• I have consistently delivered exceptional results and have received positive feedback from my superiors.

• I have significantly improved efficiency and productivity through automation.

• I have saved the company time and resources by automat...read more

Selenium is widely used for web automation while Cypress is a newer tool with better performance and debugging capabilities.

• Selenium supports multiple programming languages while Cypress only supports JavaScript.

• Cypress has a built-in test runner and debugger while Selenium requires third-party tools.

• Selenium is better for cross-browser testing while Cypress is better for end-to-end testing.

• Choose Selenium for larger and more complex projects while Cypress is better for small...read more

Find the largest difference between array elements considering only the elements at current index and before.

• Iterate through the array and keep track of the minimum value seen so far.

• Calculate the difference between the current element and the minimum value and update the maximum difference seen so far.

• Return the maximum difference seen so far.