300+ 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

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

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

Count the number of palindrome words in a given string.

• Split the string into words using space as a delimiter.

• Iterate through each word and check if it is a palindrome.

• Increment the count if the word is a palindrome.

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

JSON payload for POST request with nested object

• Use curly braces to define the object

• Use colon to separate key-value pairs

• Use double quotes for keys and values

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

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

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

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

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

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

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

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 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.

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

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

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

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.

I have worked in the Test Automation position for 5 years.

• I have 5 years of experience in Test Automation.

• I have successfully automated test cases for various projects.

• I have expertise in using tools like Selenium, Appium, and JUnit.

• I have worked on creating automation frameworks from scratch.

• I have experience in integrating automation tests into CI/CD pipelines.

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

NO and NC contacts are types of electrical switches. A motor is a device that converts electrical energy into mechanical energy. Servo and AC drives are motor controllers.

• NO (Normally Open) and NC (Normally Closed) contacts are types of electrical switches used in control circuits.

• A switch is an electrical component that can be used to make or break an electrical circuit.

• A motor is a device that converts electrical energy into mechanical energy to perform work.

• A servo drive i...read more

Non-SQL databases can be automated using programming languages and APIs.

• Use programming languages like Python, Java, or Ruby to automate non-SQL databases.

• Use APIs provided by the database vendor to automate database operations.

• Create scripts to automate repetitive tasks like data backups, data migration, and data synchronization.

• Use tools like Apache NiFi, Talend, or Pentaho to automate data integration and processing.

• Automate database monitoring and alerting using tools lik...read more

POM stands for Page Object Model. It is a design pattern used in automation testing to create a structured and maintainable framework.

• POM separates the test scripts from the web elements, making the code more readable and reusable.

• Each web page is represented as a separate class, containing its own web elements and methods.

• POM improves test maintenance by reducing code duplication and enhancing code reusability.

• It enhances collaboration between developers and testers as they ...read more

Array list and linked list are data structures used in programming.

• Array list is a dynamic array that can grow or shrink in size. It is used when random access is required.

• Linked list is a collection of nodes where each node contains a reference to the next node. It is used when frequent insertions and deletions are required.

• In automation frameworks, array list can be used to store test data or test steps while linked list can be used to implement a queue for test execution.

Yes, the CTC offering matches my expectation.

• I have researched the industry standards and found that your offering is competitive.

• The benefits and compensation package align with my expectations.

• I am satisfied with the CTC offering discussed during the interview.

The code will output 10 because the variable i is accessed through a reference of class A.

• When a subclass object is assigned to a superclass reference, the superclass reference can only access the superclass members.

• In this case, even though the object is of class B, the variable i is accessed from class A.

• Output: 10

Having knowledge of how a drive runs and its safe start and stop conditions is advantageous for an Automation Engineer.

• Understanding the different types of drives and their functions

• Knowing the safety protocols for starting and stopping drives

• Familiarity with drive control systems and programming

• Ability to troubleshoot drive issues and perform maintenance

• Examples: AC drives, DC drives, servo drives, VFDs

To move to a child window in Selenium, we need to switch to the window using window handles.

• Get the window handle of the parent window using driver.getWindowHandle()

• Get all the window handles using driver.getWindowHandles()

• Switch to the child window using driver.switchTo().window(childWindowHandle)

• Perform actions on the child window

• Switch back to the parent window using driver.switchTo().window(parentWindowHandle)

Grooming comes before sprint planning.

• Grooming is the process of refining the product backlog items and making them ready for sprint planning.

• Sprint planning is the process of selecting the backlog items for the upcoming sprint and creating a plan for their implementation.

• Grooming helps in identifying dependencies, clarifying requirements, and estimating the effort required for each backlog item.

• Sprint planning builds on the output of grooming and involves the entire team in ...read more

Username & password can be passed to the system through various methods such as environment variables, configuration files, or user input.

• Environment variables can be set and accessed through code

• Configuration files can be read and parsed to retrieve login credentials

• User input can be accepted through a GUI or command line interface

• Encryption and secure storage should be used to protect sensitive information

PLC is a digital computer used for automation of electromechanical processes in industries.

• PLC is a hardware device that receives inputs from sensors and other devices, processes them using a program, and then generates outputs to control machines or processes.

• It is used in industries for automation of various processes such as assembly lines, packaging, and material handling.

• PLCs can be programmed using ladder logic, function block diagrams, or structured text.

• Examples of PL...read more

There are various types of testing such as unit testing, integration testing, system testing, acceptance testing, and regression testing.

• Unit testing: Testing individual units or components of the software.

• Integration testing: Testing how different units or components of the software work together.

• System testing: Testing the entire system as a whole.

• Acceptance testing: Testing whether the software meets the requirements and specifications of the client or end-user.

• Regression ...read more

Schneider PLC timers are not retentive by default, but can be made retentive using the appropriate programming instructions.

• Schneider PLC timers are not retentive by default

• Retentive timers can be created using the RET instruction

• The RET instruction stores the current timer value in a specified memory location

• The stored value can be used to resume the timer from where it left off after a power cycle or program restart

The UNIX command for copying a file is 'cp'.

• The 'cp' command is used to create a copy of a file or directory.

• The basic syntax of the 'cp' command is 'cp source_file destination_file'.

• If the destination file already exists, it will be overwritten unless the '-i' option is used.

• To copy a directory and its contents, the '-r' or '-R' option is used.

• Examples: 'cp file1.txt file2.txt' or 'cp -r directory1 directory2'

I have used various types of sensors with PLC.

• Proximity sensors

• Temperature sensors

• Pressure sensors

• Level sensors

• Flow sensors

• Position sensors

• Photoelectric sensors

• Ultrasonic sensors

• Humidity sensors

• Gas sensors

Different protocols used in automation engineering

• Modbus

• Profibus

• DeviceNet

• Ethernet/IP

• CANopen

• AS-Interface

• Foundation Fieldbus

• HART

• BACnet

• LonWorks

I break down the complex task into smaller manageable parts, prioritize them, and use problem-solving skills to tackle each part effectively.

• Break down the task into smaller components

• Prioritize the components based on importance and dependencies

• Utilize problem-solving skills to address each component effectively

• Collaborate with team members for input and support

• Regularly review progress and adjust strategies as needed

Xceptor is used for data extraction and Automation Anywhere is used for automating repetitive tasks.

• Xceptor is used in financial services for data extraction and processing.

• Automation Anywhere is used for automating repetitive tasks like data entry, invoice processing, etc.

• Xceptor can be used for reconciling trades and managing risk in financial services.

• Automation Anywhere can be used for automating HR processes like onboarding and offboarding employees.

• Xceptor can be used f...read more

VFD selection depends on motor voltage, current, and power rating.

• Check motor nameplate data for voltage, current, and power rating

• Select VFD with compatible voltage and current rating

• Ensure VFD power rating is equal to or greater than motor power rating

• Consider additional features such as overload protection and communication protocols

• Consult manufacturer's specifications and guidelines

PLC programs can be written in various languages such as ladder logic, structured text, function block diagram, and sequential function chart.

• Ladder logic is the most commonly used language in PLC programming.

• Structured text is similar to programming languages like C and Pascal.

• Function block diagram uses graphical blocks to represent functions.

• Sequential function chart is used for complex processes with multiple steps.

• The choice of language depends on the application and the...read more

Communication between SCADA/HMI & PLC is crucial for automation. It enables real-time monitoring and control of industrial processes.

• SCADA/HMI sends commands to PLC for process control

• PLC sends data to SCADA/HMI for real-time monitoring

• Communication protocols like Modbus, Profibus, and Ethernet/IP are used

• Redundancy and fault-tolerant systems are implemented for reliability