Which device handles the logic for each HVAC piece of equipment in building automation?

Which device handles the logic for each HVAC piece of equipment in building automation?

• A. Gateway
• B. Sensor
• C. PLC
• D. HMI

Answer: (C)

The device that handles the logic for each HVAC piece of equipment in building automation is the programmable logic controller. A PLC runs a control program that constantly reads inputs from sensors (like temperature, humidity, pressure, occupancy), applies programmed rules and sequencing (setpoints, deadbands, interlocks), and updates outputs to operate actuators (such as contactors, dampers, valves, fans, and pumps). This setup lets the system coordinate multiple components, respond to changes, and maintain desired conditions with reliable timing and safety interlocks. The PLC can be centralized or distributed, and its program can be updated as system needs evolve. Gateways, by contrast, mainly handle communication between different networks and protocols; sensors provide measurements rather than decision-making logic; HMIs offer a human interface for monitoring and manual control but do not execute the control logic themselves.

The device that handles the logic for each HVAC piece of equipment in building automation is the programmable logic controller. A PLC runs a control program that constantly reads inputs from sensors (like temperature, humidity, pressure, occupancy), applies programmed rules and sequencing (setpoints, deadbands, interlocks), and updates outputs to operate actuators (such as contactors, dampers, valves, fans, and pumps). This setup lets the system coordinate multiple components, respond to changes, and maintain desired conditions with reliable timing and safety interlocks. The PLC can be centralized or distributed, and its program can be updated as system needs evolve.

Gateways, by contrast, mainly handle communication between different networks and protocols; sensors provide measurements rather than decision-making logic; HMIs offer a human interface for monitoring and manual control but do not execute the control logic themselves.