What is the difference between a point-to-point check and functional performance testing?

• A. Point-to-point checks test entire system; FPT tests individual components.
• B. They verify individual sensors/actuators; FPT verifies system-wide performance and operation.
• C. They are the same; just different terminology.
• D. Point-to-point checks are for graphs; FPT for schedules.

Answer: (C)

The essential distinction is between verifying individual signal paths and validating system-wide operation. A point-to-point check focuses on the wiring and communication between a field device and the control system—making sure a sensor, its input to the controller, and the controller’s output to an actuator are correctly connected and that the signal path behaves as expected. It’s about confirming that each specific link in the control loop is correct and responsive.

Functional performance testing, on the other hand, looks at how the entire system behaves under real or simulated operating conditions. It checks that sequences, interlocks, and device coordination deliver the intended performance, such as meeting setpoints, response times, energy use, and occupant comfort, across the system’s operation.

So they’re not the same. Point-to-point checks ensure accurate wiring and basic signal integrity, while functional performance testing validates that the system performs as designed when operating as a whole. Both are important parts of commissioning, but they cover different levels of verification.