In making models of real world problems or real world processes, the need for transfer of data between model and external files, applications or other devices becomes important. This paper illustrates the use of automatic data transfer in model construction and in process control. In a typical model construction and verification process, real date plays an important role. Once a model is made of the target system, real data is fed into the model, and the model output is compared to the output of the real system. The result of the comparison is used as a basis for refining model structure, model parameters, or both. The Dynamic Data Exchange (DDE) object and the Archive object of POWERSIM may be used in a model to import and export data during simulation. This greatly reduces the amount of work involved in checking model against reality. DDE can also be used to set up a data analysis, for example, by launching a spreadsheet or a statistical program. In combination with the multiple runs feature of POWERSIM, a series of model structures and model parameters can be tested with real data without manual intervention. In a research project aiming at developing a model of the biological process of fish growing in a fish farm, the above tools have allowed for extensive use of data from fish farms in the process of model construction and verification. The basic feedback loop of a process control system, involves measurements (import of data), comparison between measured values and desired values, followed by a controlling action (output of data) aiming at closing the gap between actual and desired process state. The data transfer protocols of POWERSIM make it possible to implement process control systems as POWERSIM models, and linking the models to the physical process. A range of input/output devices for the Windows operating systems supports DDE or Net-DDE, and may therefore be used directly together with POWERSIM.

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Date created

• 1995

Type

• Document

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• Processing documentation available at: https://wiki.albany.edu/display/SCA/Processing+Ingested+Digital+Files

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• Creative Commons BY-NC-ND Attribution-NonCommercial-NoDerivs 4.0 International

  
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12420ec6bd5f758d2b4dea59aabd75a9

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23d738ba88f8333bc39725f9cb5bd0b8

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b83f2ce2912343b559f967dd985da515

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Collection

System Dynamic Society Records

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Collecting area

• This collection is part of the University Archives