32 PLC Programmer Interview Questions with Example Answers

PLC (programmable logic controller) programmers are professionals in the supply and manufacturing industries who program logic controllers to ensure assembly lines and machines operate effectively. Part of becoming a PLC programmer is attending an interview that discerns whether you have the right skills, experience and technical knowledge to work effectively with PLC devices. Understanding the questions interviewers may ask allows you to prepare the correct answers that impress a hiring manager. In this article, we discuss the definition of interview questions for PLC programmers, provide 30 interview questions and share two with example answers.

What are PLC programmer interview questions?

PLC programmer interview questions refer to the interview questions used in a PLC programmer recruitment process, where hiring managers seek to understand whether candidates have the right skills, industry knowledge and technical ability to work with complex technology such as industrial computers. Interview questions for PLC programmers can usually be categorised into three sections. These are general questions, questions regarding your background and experience and in-depth interview questions. Usually, these three categories contain a series of open-ended questions that require candidates to provide in-depth yet concise answers.

Sometimes, hiring managers may present PLC programming candidates with a scenario, such as a technical fault and ask candidates to explain their problem-solving process. The candidate's response helps the hiring manager to determine the candidate's key hard and soft skills and whether they can approach PLC programming tasks constructively. Depending on the seniority of the PLC programming role, interviewers may also ask questions about candidates' career ambitions such as leadership opportunities, and what traits make them the ideal candidate for this type of role.

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General interview questions

General interview questions for PLC programmers typically aim to discern the candidate's general skills and characteristics. Usually, these questions aren't specific to a PLC programming role but aim to determine whether the candidate is a good match for the organisation's workplace culture and whether they have the desired work ethic.

More specific general PLC programming questions may ask candidates how they balance operating and programming and how they maintain multiple industrial computers to determine how they manage pressure and tasks. Additionally, general interview questions typically involve asking candidates how they collaborate with other professionals. Here are some examples of plc programming general interview questions:

1. In simple terms, what is the definition of PLC?

2. What would you describe as PLC's main role in automation?

3. What five traits do you think you have that are necessary for a PLC programming role?

4. How do you manage a proper work-life balance?

5. How do you keep yourself motivated at work?

6. Explain your attitude to working with other professionals in a PLC programming team.

7. Why do you think you're the best candidate for this role?

8. What attracts you to this role?

9. When did you first discover a passion for working with computers?

10. What are some of your main hobbies?

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Questions about experience and background

Questions about experience and background usually aim to understand whether candidates have the correct experience working with industrial computers in a manufacturing capacity to complete the expected daily tasks. These questions typically allow the candidate to talk about how their previous experience provided them with useful skills and how they have used these to help their employer.

Additionally, questions about experience and background allow candidates to go into further depth about any qualifications or certifications that they believe the employer may value. For example, a candidate may have the opportunity to introduce their degree in computer science and explain how this allows them to complete their tasks to a better standard. Additionally, candidates can introduce specialist certifications that may provide them with a competitive advantage, such as software development or coding certification. Here are ten examples of experience and background:

1. What qualifications do you have that you think have benefited you the most?

2. What programming languages have you worked with?

3. What are the main types of PLC that you have worked with in your previous role?

4. What's the best way to manage conflicting opinions with a colleague?

5. When did you last test and commission a PLC system?

6. What would you say is your biggest achievement to date from your professional experience?

7. What skills did you take from your last role that you think would benefit this organisation?

8. If you could have changed one thing about your last role, what would it be?

9. Has there been an instance where you couldn't solve a fault and how did you tackle this?

10. Explain the importance of PLC in the manufacturing and assembly line process.

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In-depth interview questions

In-depth interview questions usually mean that candidates can provide more detailed responses to open-ended questions. In this case, candidates can provide anecdotes from their previous experience working with industrial computers and explain how they used coding and complex software to maintain or repair systems. Candidates can go into further depth about their problem-solving and decision-making processes, demonstrating critical skills necessary for a PLC programming role.

In some cases, these questions begin with asking the candidate to respond to a scenario. From this, the candidate explains how they use their skills and knowledge of operating industrial computers to provide clear answers that address all action points within the scenario. Here are some examples of in-depth interview questions:

1. What is the difference between fixed and modular PLCs?

2. What different PLC brands are there currently operating in the industry?

3. Please explain the fundamental elements of ladder logic programming.

4. If a colleague approached you asking you to fix a fault because they can't do it, how would you respond and why?

5. Aside from manufacturing, what are the other applications of PLC?

6. What would you regard to be the biggest advantages in PLC?

7. How important do you think teamwork is in a PLC programming role?

8. How do you keep yourself informed about developments in PLC?

9. What are your training styles for training new PLC programmers?

10. What benefits does your approach to PLC programming offer this organisation?

Related: 10 Problem-Solving Interview Questions (With Example Answers)

Interview questions with sample answers

When answering interview questions for a PLC role, it's important to provide well-structured answers that demonstrate proficiency in coding and computer software. To do this, consider using the STAR answer approach. The STAR method means that candidates structure their responses by addressing the situation, task, action and response.

This allows candidates to address each section of the hiring manager's question, providing an in-depth yet concise response without the risk of over-explaining or going off-topic. Here are some examples of how to answer some programmer interview questions:

1. Can you explain what PLC means?

Technical questions such as these test your subject expertise. It's important for candidates to have an in-depth understanding of their industry before applying for a role, as this allows them to approach each task with a clear understanding of the equipment they use. When answering this question, it's best to provide a short answer that directly addresses the key components of PLC. Try not to over-explain or provide a longer answer than necessary, as this question is only testing your basic knowledge.

Example answer: ‘PLC is short for Programmable Logic Controllers. Essentially, a PLC is an industrial computer that's used by many key industries to monitor inputs and switch outputs to on or off. This automates a process or device and streamlines a decision-making process. PLC combines both hardware and software and acts as a control point for automated mechanisms.’

2. Explain how you last managed workplace conflict with a colleague.

Questions about workplace conflict primarily aim to understand your problem-solving process, communication and prioritisation of healthy workplace relationships. The best way to answer this question is to concentrate on the solution and its result rather than on the problem itself. You can also briefly explain how you ensured that issues such as these don't impact your work and how this benefits the employer.

Example answer: ‘The last time I managed workplace conflict was when a colleague and I disagreed on a piece of coding for a PLC in waste management. Instead of allowing this situation to affect our working relationship, I sat with the colleague and asked their point of view and why they thought this. Instead of undermining their opinion, I verbally appreciated their thoughts and communicated why I believed my opinion was a more effective solution.

From this, I suggested another example where their coding idea would have been beneficial and urged them to use this technique in future tasks. As a result of this, our working relationship remained positive, and we worked productively together on tasks that required collaboration.’