PLC Automation Engineer

ON.energy is building the power infrastructure that makes the AI era possible. As AI demand surges past what the grid and traditional data centers can support, ON.energy provides a new class of power technology proven at gigawatt scale and trusted by the world’s leading cloud and AI companies. Our systems are already deployed across 2.5 GW of hyper-scale campuses, validated by top U.S. national labs, and certified for grid-safe operation by major utilities. With real products in the field, we’re scaling faster than the grid can, transforming power from a bottleneck into a competitive advantage for the companies building the future.

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.