Controllers and CPUs form the processing layer of PLC, DCS, safety, and industrial automation systems. Their architecture typically combines a central processor, program and data memory, communication interfaces, backplane or rack connections, and diagnostic functions. Depending on the platform, controller hardware may operate as a standalone CPU, redundant processor, rack-based controller, or distributed control node. Key technical characteristics include processor performance, memory capacity, communication protocol support, redundancy capability, firmware generation, and compatibility with specific I/O architectures. Functionally, these modules execute control logic, coordinate process sequences, exchange data with field and supervisory devices, and manage system diagnostics. Replacement selection should follow the exact manufacturer catalog number, hardware revision, communication requirements, memory specification, and installed control-system architecture.
