Quality Assurance Engineer, PLC Automation

ON.energy is setting the standard for large load interconnection. ON’s patented AI UPS™ is a medium-voltage UPS that serves as a firewall, protecting the data center from the grid, and the grid from the data center. With multiple gigawatts currently under construction, we are enabling grid-safe data centers.

The Quality Assurance Engineer is responsible for hands-on experience in PLC programming, industrial protocol testing, and Python-based test automation. Skilled in designing and executing functional and integration test cases across PLC platforms and communication protocols.

Key Responsibilities:

Design, develop, and execute Unit tests, functional, integration, and regression test cases for PLC-based control systems

Write and maintain Python-based automated test scripts for testing PLC I/O, HMI interfaces, and communication protocols

Develop, review, and validate PLC code (Ladder Logic, Function Block Diagram, Structured Text) across Siemens S7-1200/1500

Collaborate with controls engineers to define acceptance criteria and validate system requirements

Identify, document, and track defects using tools such as Azure Devops or equivalent; lead root cause analysis for critical failures

Conduct Hardware-in-the-Loop (HIL) and Software-in-the-Loop (SIL) testing where applicable

Produce clear test plans, reports, and traceability matrices aligned with release timelines

Required Experience & Skills

University degree in Software Engineering, Computer Science, Quality Engineering, or a related technical field.

5+ years of hands-on experience in PLC programming and testing across Siemens platform.

5+ years of experience building and maintaining automated test frameworks using pytest or equivalent python framework.

3–5 years of experience with Siemens TIA Portal for PLC development, diagnostics, and commissioning support.

Experience designing and executing functional and integration tests, including test case development, defect tracking, and validation of fixes.

Working knowledge of industrial communication protocols such as S7, Modbus TCP/RTU, and OPC-UA.

Preferred Experience

Proficiency in automated unit testing the PLC Logic

Experience with SCADA systems

Familiarity with Agile / Scrum methodologies in industrial settings

Knowledge of functional safety standards such as IEC 61508 / IEC 62061

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For US-based roles - What you’ll get:

Competitive salary + annual performance-based bonus eligibility

Medical, dental, and vision insurance

401(k) with company match

Paid time off and company holidays

For Mexico-based roles - What you’ll get:

Competitive salary + annual performance bonus eligibility

Christmas Bonus (Aguinaldo): 30 days

Major medical expenses and life insurance

Paid time off and holidays (per local policy)

For all roles:

Professional development and growth opportunities

Opportunity to grow with a mission-driven team shaping the future of clean energy

Equal Opportunity: ON.energy is committed to equal employment opportunity and to maintaining a work environment free of harassment, discrimination, or retaliation.

Benefits vary by role and location and are subject to change.

Agency Notice: ON.energy does not accept unsolicited resumes from staffing agencies, search firms, or third-party recruiters. Resumes submitted without a fully executed Master Services Agreement (MSA) and a written request from an authorized member of our Talent Acquisition team will be considered the property of ON.energy. No placement fees or compensation will be paid for unsolicited candidate submissions.