The document provides reference information on the structure and functions of CPU 41x modules used in Siemens S7-400 programmable logic controllers. It describes the controls, indicators, memory, interfaces, parameters, and operating modes of the CPU modules. Specifically, it covers the CPU's role as a PROFINET controller and device, capabilities for multicomputing and direct communication, and diagnostics features. The document is intended as a technical reference for qualified personnel working with S7-400 automation systems.