The complexity of modern process plants is steadily increasing. To overcome this potential source of error it is obvious that a abstract way to model such systems is needed. Piping and Instrumentation Diagrams or P&IDs are used in various areas to model these complex plants. To evolve the usage of P&IDs in the industry, significant support of modeling tools is needed. Our research showed that currently few tools allow modeling of such diagrams.
The Piping and Instrumentation Diagram (P&ID), is primarily derived from the Process Flow Diagram (PFD). P&ID is used to support or guide the design and construction of process plants. P&ID helps to communicate between designers, constructors, operators and owners of the plant by providing a schematic representation. The schematic representation elaborates important details of piping and instrumentation and should tie together the system description, system flow, electric control schematic and the control logic. The semantic of the diagram should help to demonstrate the physical sequence and connectivity of equipment in a system. Another important concept is the isometric drawing scheme or the orthographic physical layout. In other words the placement of elements in the diagram should practically represent the physical placement of components in a plant.
UML Extension Techniques
Although UML offers a broad range of diagrams to model systems there will always be a need to model domain specific characteristics. Another fact is that it will always need time to take care of new technologies in the UML standard.
Two overcome these drawbacks UML allows to adapt the standard.
Basically there are two different approaches: lightweight extensions through profiles and heavyweight extensions through meta-model modifications. Enterprise Architect mainly features extension through UML Profiles, this is why we chose this approach.
Implementation of P&ID Profiles in Enterprise Architect
Enterprise Architect offers a powerful extension mechanism based on the standardized UML Profile principles. Enterprise Architect lets you access this functionality via the Model Driven Generation Technologies SDK. Enterprise Architect has a built in MDG Technology Creation Wizard which eases initial contact with the overwhelming size of the tool.
Visualizing P&ID elements with Shape Script
Elements and connectors which were extended via UML stereotyping conform to the standard UML notation in terms of shape, color and labeling. Enterprise Architect offers the possibility to define the appearance of extended elements and connectors using their proprietary Shape Scripts language. Shape Script allows the developer to define size, shape, orientation and color of custom elements. Furthermore Shape Script provides some methods for reflection, with which the graphical representation can react to the properties of the given instance of the element. Shape Script uses a C-like syntax.