6 Programmable Logic Controller Programmer Interview Questions and Answers

Introduction

This question evaluates your understanding of safety regulations and your commitment to implementing them in your engineering designs, which is vital in the field of controls engineering.

How to answer

• Discuss your knowledge of relevant safety standards (like IEC 61508, ISO 13849).
• Explain your approach to risk assessment and hazard analysis.
• Detail how you incorporate safety features into your control design (e.g., redundancy, fail-safes).
• Provide examples of past projects where safety standards were critical.
• Mention your commitment to ongoing training and staying updated on safety regulations.

What not to say

• Ignoring the importance of safety standards in engineering.
• Claiming that safety is not your responsibility.
• Providing vague answers without specific examples.
• Failing to mention any continuous learning or improvement efforts.

Example answer

“In my role at Valeo, I always start by conducting a thorough risk assessment using the IEC 61508 framework. For a recent control system design, I implemented safety features like emergency stop buttons and redundant sensor systems to ensure compliance with ISO 13849. I also regularly participate in safety training to stay current with industry standards. As a result, we achieved a safety integrity level of SIL 2 for our project, enhancing overall system reliability.”

Introduction

This question evaluates your troubleshooting skills, analytical thinking, and systematic approach to problem-solving, which are essential for this role.

How to answer

• Outline a step-by-step troubleshooting process
• Explain how you gather data and diagnose the issue
• Discuss the tools and techniques you use for diagnostics
• Share an example of a specific issue you resolved and the outcome
• Highlight the importance of documenting the process for future reference

What not to say

• Relying solely on trial and error without a systematic approach
• Failing to mention safety protocols during troubleshooting
• Neglecting to involve team members or seek help when needed
• Not discussing the importance of documentation

Example answer

“When troubleshooting a PLC malfunction, I start by reviewing the system logs and error codes to identify any anomalies. For example, when a production line went down due to a fault in the Mitsubishi Q-series PLC, I methodically checked input/output points and wiring connections. I used a multimeter for physical checks and software diagnostics tools for data analysis. Once I pinpointed the faulty sensor, I replaced it, restoring functionality and preventing future downtime by implementing alerts for similar issues. Documentation of this process helped the team respond faster in the future.”

Introduction

This question assesses your understanding of industry standards, quality assurance, and your commitment to maintaining high programming standards as a Lead PLC Programmer.

How to answer

• Discuss your knowledge of relevant standards like IEC 61131-3
• Explain your process for reviewing and testing code for compliance
• Share how you stay updated on industry best practices and technological advancements
• Describe how you incorporate feedback from audits or peer reviews
• Mention any training or mentoring you provide to team members

What not to say

• Claiming to know everything without acknowledging the need for continuous learning
• Overlooking the importance of documentation and version control
• Suggesting that following standards is not necessary
• Failing to mention collaboration with other professionals in ensuring standards

Example answer

“I follow the IEC 61131-3 standard rigorously in my programming. I have a robust process in place for code reviews and testing environments to ensure compliance. Additionally, I regularly attend industry workshops and webinars to stay updated on best practices. I also emphasize the importance of thorough documentation and version control within my team to uphold quality standards. This structured approach has consistently led to successful project audits with minimal issues.”

Introduction

This question evaluates your commitment to continuous learning and professional development, which is essential for staying competitive in the rapidly evolving field of automation.

How to answer

• Mention specific resources you use, such as online courses, webinars, or industry publications.
• Explain how you apply new knowledge or skills in your current role.
• Share any relevant certifications or professional memberships.
• Discuss your involvement in industry events or communities.
• Highlight the importance of networking with peers and learning from their experiences.

What not to say

• Claiming that you don't need to stay updated, as the industry is stable.
• Being vague about your learning sources or activities.
• Focusing solely on past experiences without mentioning current or future learning plans.
• Neglecting to mention the impact of new knowledge on your work.

Example answer

“I regularly follow industry publications like Control Engineering and participate in webinars hosted by organizations like the International Society of Automation. Additionally, I completed a certification in Advanced PLC Programming last year, which helped me implement new strategies in my current projects. Networking with professionals at events like the Automation Fair also keeps me informed about emerging trends and technologies.”

Introduction

This question evaluates your commitment to safety standards and your understanding of reliability in industrial automation, which are crucial aspects of a PLC Programmer's role.

How to answer

• Discuss relevant safety standards or protocols you adhere to (e.g., IEC 61508)
• Explain your process for testing and validating PLC programs before deployment
• Mention how you document your programming and testing processes
• Describe your approach to continuous monitoring and updates post-deployment
• Highlight any experiences where safety or reliability was notably improved

What not to say

• Neglecting to mention any standards or protocols
• Providing vague answers without specific safety practices
• Overlooking the importance of documentation
• Failing to discuss post-deployment monitoring

Example answer

“I adhere to IEC 61508 standards for functional safety in my PLC programming work. During a project at Coca-Cola, I implemented a series of rigorous testing protocols, including simulation and field testing, to ensure the reliability of our control systems. I also maintain detailed documentation for all programs and conduct regular reviews to update them based on operational feedback. This proactive approach has significantly minimized our downtime and enhanced system reliability.”

Introduction

This question assesses your troubleshooting process and analytical skills, which are crucial for identifying and resolving issues in PLC systems.

How to answer

• Outline a systematic approach to troubleshooting, such as starting with the basics (power, connections)
• Explain how you would use diagnostic tools and software
• Discuss the importance of consulting documentation and previous project notes
• Mention collaboration with team members or more experienced colleagues when necessary
• Highlight any specific examples of successful troubleshooting experiences

What not to say

• Suggesting you would guess or rely solely on intuition
• Ignoring the importance of documentation and previous experiences
• Failing to mention teamwork or collaboration
• Not detailing a step-by-step approach or methodology

Example answer

“When troubleshooting a PLC system, I start by checking the power supply and ensuring all connections are secure. I then use diagnostic tools like ladder logic software to identify any error codes. For example, during my project, I encountered a communication error with a sensor. By reviewing the wiring diagram and consulting my supervisor, we identified a loose connection, which resolved the issue and restored functionality.”