Process-engineering components such as pumps, valves, containers and measured-value pickups have to date been shown in a first diagram, and the program code for instrumentation and control has been shown in a second diagram. To improve clarity, these two diagrams have been combined in a general diagram produced manually. The reason for this is that such a general diagram is the only basis on which it is possible for the process-engineering operatives and the control operatives to cooperate.
In the graphical representation, the program code for instrumentation and control comprises a multiplicity of sub-diagrams, particularly function diagrams for the individual level. These sub-diagrams are used for implementing the required process-engineering functions, such as regulation, partial or group control, step control and measurement and also measured-value correction and the like. The individual sub-diagrams have corresponding software modules which are connected to one another. The sub-diagrams themselves are also linked to one another, for example by defined break points. The sub-diagrams are graphical representations of the individual sequences of the program code.
The known general diagram is an exclusively graphical representation. Consistency and freedom from error have to be ensured manually. Changes in the program code for instrumentation and control or in the process-engineering components likewise have to be made manually. The management of change is therefore complex and prone to error. Continual matching of the program code or of the process-engineering components to changes in the general diagram, or vice versa, is virtually impossible.