Who makes PLCs for AI data centers

The building management system decides what the plant should do; the PLCs make it happen. They run the fast, deterministic loops — sequencing chillers, modulating valves and dampers, staging pumps, handling interlocks — on hardware built to run continuously for years without an operating system underneath it that might decide to update itself. The division of labour matters because of what happens when the layers above fail. A well- built plant keeps its safety interlocks and its basic sequences in the PLC, so that a failure of the supervisory system, the network, or an optimisation layer leaves the cooling still running on local control. Sites that pushed control logic up into the management layer have discovered the alternative, and this is the main design question in this part rather than any feature comparison. AI halls raise the stakes because the time between a cooling fault and a thermal problem is much shorter at high rack density, so the control response has to be local and fast. What to look for is redundancy at the controller and the network between controllers, whether the programming is open enough that the operator is not locked to one integrator, and how the interface to the layer above is defined — the optimisation software in this same part depends on being able to write setpoints into these controllers safely.