Quality Assurance Engineer, PLC Automation

ON.energy is building the backbone of energy and AI infrastructure powering grid-safe data centers and mission-critical facilities. The company supplies and operates hyperscale power systems that solve the toughest resilience challenges, delivering custom solutions for AI data centers, mission-critical facilities, and front-of-the-meter assets. ON recently announced a 5GW partnership, with 3GW currently under construction across multiple hyperscale data center campuses. With patented technology and proprietary software, ON.energy develops projects worldwide that set new benchmarks for resilience.

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

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.
• Accommodations: If you need an accommodation during the application process, email [email protected]
• 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.