The Use of Software Objects

In an effort to reduce the complexity of engineering and software designs, many systems now use the concept of so-called objects . These allow even the most complex engineering designs or software constructs to be built up from smaller building blocks known as objects. Most open applications are now based on object-oriented software, since this technique lends itself to efficient software development and easier software integration between different applications. 

An object basically consists of inputs, outputs, a function (or functions) and parameters. When the object is processed (executed), the outputs are calculated based on the function of the object, the input values and the settings of the internal parameters. Some objects have a fixed function (such as an addition function, or a PID [proportional, integral and derivative] control loop), and some may have their object functions modified or even created from scratch. 

The use of object-oriented software has been estimated to save literally millions of dollars on new plants, and these savings only estimate the savings in actual engineering hours. These savings will obviously be reflected in the reduced cost associated with vaiidating standard objects as opposed to application-specific or bespoke software. 

As well as control systems being configured using objects, many other devices and systems are configured using this object-oriented approach. Fieldbus device descriptions are examples of objects that contain inputs, internal parameters, a function and an output. A Fieldbus device may t5q)ically have multiple functions, a dozen or more inputs and potentially hundreds of parameters and outputs that may be accessed. 

The problem with objects is that they can vary considerably, from a simple addition function (two inputs, one function, no parameters and one output) to something as complex as an object used to desaibe a complete centrifuge. 

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