Preparing for an interview at Plexus requires a balanced approach. You must demonstrate both deep technical competence and the ability to communicate complex ideas clearly to a diverse group of stakeholders.

Technical Excellence & Hardware Empathy – You must show that you understand how software interacts with physical circuitry. Brush up on fundamental electrical engineering concepts, microcontrollers, and low-level C/C++ concepts. Even if you are a pure software candidate, showing an interest in and understanding of hardware architecture will set you apart.

Structured Problem Solving – When faced with technical scenarios or coding questions, do not rush to write code. Walk your interviewer through your thought process, state your assumptions clearly, and discuss edge cases. Plexus values methodical, safe design over quick, unverified hacks.

Presentation & Communication Skills – One of the most distinctive elements of the Plexus hiring process is the technical presentation. You must be able to articulate your past achievements, technical decisions, and project methodologies to a panel of engineers. Focus on why you made certain choices, what you learned, and how you measured success.

Collaboration & Cultural Alignment – Plexus is a highly collaborative environment. Your interviewers will evaluate how you handle feedback, how you work in multidisciplinary teams, and how you navigate ambiguity. Be prepared with concrete examples of successful teamwork and conflict resolution.

The interview process at Plexus is thorough and designed to evaluate both your technical capabilities and your cultural fit. While the process can vary slightly by location and team, it generally follows a highly structured, multi-stage path.

The journey begins with an initial HR screening call to discuss your background, interests, and basic alignment with the role. This is followed by a technical screening, which is typically a phone or video call with a hiring manager or senior engineer focusing on basic engineering concepts, your resume, and technical problem-solving.

For candidates who pass the initial screens, the final round is a comprehensive evaluation. Historically conducted as a full-day onsite visit, this stage is now frequently organized as a structured virtual panel via Microsoft Teams, though some locations still prefer onsite visits that include a facility tour. A central element of this final round is a candidate-led presentation, where you present your background and projects to a panel of engineers and managers. This is followed by deep-dive technical interviews, behavioral sessions, and discussions with engineering leadership.

This visual timeline illustrates the typical progression from your initial application to the final decision. Candidates should expect the entire process to take anywhere from three to six weeks. Use this timeline to pace your preparation, ensuring you allocate sufficient time to build your technical presentation before reaching the final round.

To succeed at Plexus, you must understand the specific competencies your interviewers are trained to evaluate.

Embedded Systems & C/C++ Programming

This area evaluates your ability to write efficient, reliable, and safe code for resource-constrained environments. Because Plexus products often operate in medical or aerospace environments, code quality and safety are paramount.

Be ready to go over:

• Memory Management – Dynamic allocation vs. static allocation, stack vs. heap, and avoiding memory leaks in long-running embedded systems.
• Microcontroller Fundamentals – Interrupt handling, timers, GPIO configuration, and register-level programming.
• Concurrency – Real-Time Operating System (RTOS) concepts, task scheduling, mutexes, semaphores, and volatile variables.
• Advanced concepts (less common) – Direct Memory Access (DMA) configuration, bootloader design, and hardware-software co-design principles.

Example questions or scenarios:

• "You are experiencing an intermittent system crash that seems related to stack overflow. How do you debug and resolve this issue?"
• "Walk me through how you would configure an interrupt service routine (ISR) to handle high-frequency sensor data without blocking the main application loop."

Hardware Integration & Circuit Fundamentals

Even as a software engineer, you must be able to read schematics and understand the physical medium your software controls. Interviewers will test your ability to bridge the gap between bits and electrons.

Be ready to go over:

• Schematic Reading – Identifying basic components such as resistors, capacitors, transistors, and operational amplifiers.
• Communication Protocols – Deep understanding of I2C, SPI, UART, and CAN bus protocols, including physical characteristics and timing requirements.
• Signal Conditioning – Basic analog-to-digital conversion (ADC), digital-to-analog conversion (DAC), and filtering concepts.
• Advanced concepts (less common) – RTL design, schematic capture, and electromagnetic compatibility (EMC) mitigation techniques in software.

Example questions or scenarios:

• "How would you write a software driver to communicate with a new temperature sensor over an I2C bus? What error-handling mechanisms would you include?"
• "Explain how a software-based digital filter can be used to clean up a noisy analog signal read from a sensor."

The Technical Presentation

The presentation is your opportunity to showcase your engineering maturity. You will be asked to present for 15 to 30 minutes on your background, a significant engineering project (such as a university capstone or a major professional deliverable), and your technical accomplishments.

Be ready to go over:

• Project Architecture – High-level block diagrams of the system you worked on, explaining the relationship between software and hardware components.
• Engineering Decisions – Why you chose specific technologies, protocols, or design patterns, and what trade-offs you evaluated.
• Problem Solving – A detailed walkthrough of a complex technical challenge you encountered during the project and how you methodically solved it.
• Advanced concepts (less common) – Showing how your project aligned with formal quality standards, testing frameworks, or manufacturing constraints.

Example questions or scenarios:

• "Why did you choose an RTOS over a bare-metal state machine for this specific project?"
• "If you were to redesign this system today with unlimited budget, what architectural changes would you make to improve reliability?"

Software Lifecycle & Requirements Engineering

At Plexus, software must be highly documented, traceable, and verified. This area evaluates your understanding of disciplined software engineering processes.

Be ready to go over:

• Requirements Traceability – Mapping customer requirements to software design specifications and verification tests.
• Testing Methodologies – Unit testing, integration testing, system testing, and regression testing in an embedded environment.
• Configuration Management – Version control strategies, branching models, and release documentation.
• Advanced concepts (less common) – Medical device software standards (e.g., IEC 62304) or aerospace software standards (e.g., DO-178C).

Example questions or scenarios:

• "How do you ensure that a critical safety requirement is fully verified by your test suite?"
• "Describe your process for managing code changes and releases when multiple developers are working on the same codebase."

As a Software Engineer at Plexus, your daily work will span the entire product development lifecycle. You will transition regularly between high-level architectural design, low-level coding, and hands-on laboratory testing.

Your primary responsibilities will include:

• Embedded Software Design – Developing, debugging, and maintaining embedded software and system concepts that satisfy strict customer and regulatory requirements.
• Cross-Functional Collaboration – Working closely with electrical engineers to define hardware-software interfaces, mechanical engineers to understand physical constraints, and quality engineers to ensure compliance.
• Testing & Verification – Developing and executing comprehensive software design verification test (DVT) plans to prove your software meets all requirements specifications.
• Configuration & Release Management – Utilizing configuration management and version control tools to deliver controlled, high-quality software releases to customers.
• Customer Interaction – Participating in technical reviews, translating customer needs into engineering specifications, and presenting design solutions directly to client stakeholders.