Funktionsplan

Funktionsplan, in German engineering and automation contexts, is a graphical representation that shows the functional structure of a system. It depicts Functions or function blocks, their inputs and outputs, and the signals or data that connect them. Used in general system design, a Funktionsplan helps describe what the system must do and how information flows between components, aiding design, documentation, and communication among engineers.

In the field of programmable logic controllers (PLCs), Funktionsplan is also the name of a programming language, historically known as FUP. It presents logic as interconnected function blocks rather than sequential steps, with signals or data lines linking blocks. This visual language is common for implementing simple logical operations, timers, and discrete control tasks in Siemens environments and other IEC 61131-3 contexts.

Structure and notation typically involve function blocks, basic operations (such as AND, OR, NOT), comparators, timers, and input/output data. A Funktionsplan may be arranged horizontally or vertically, emphasizing function and signal flow over a strict execution order. The representation supports modular design, easy tracing of interfaces, and straightforward maintenance.

Applications include process control, machine automation, and system design, where it helps planners verify interfaces, understand interactions between subsystems, and communicate requirements to stakeholders. It is related to, but distinct from, flowcharts or sequence diagrams; it shares concepts with block diagrams and function block diagrams, and in German-speaking contexts the term encompasses both the general design concept and the PLC programming variant (FUP).