Building Automation Systems
A BAS connects controllers, a network, and a central interface so facility staff can schedule equipment, trend data, and respond to alarms from a laptop or phone. Office towers, schools, hospitals, and campuses depend on them. When buying, favor open protocols such as BACnet, which lets different brands talk to each other, so you're not locked into one vendor forever. Ask about cybersecurity, remote access, user licenses, and who will own the programming. Used controllers are rarely worth the risk, since firmware support and parts availability matter.