Evaluation of alternative approaches for interaction between ladder logic on a programmable controller and algorithmic processing

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Virginia Polytechnic Institute and State University


In this thesis an evaluation was performed of different approaches for interaction between algorithmic processing, and ladder logic and memory locations in a programmable controller. The evaluation provides a potential customer with information to make a decision for selection of the equipment used in this work. The specific capabilities of two approaches to programmable controller interfacing, a) via an intelligent I/O module and b) via a host computer on a network have been detailed. The attributes for comparison of the above two approaches were, a) capability of accessing information from memory locations in the programmable controller, b) capability of processing information in parallel to the programmable controller and c) memory considerations associated with each approach.

The evaluation was performed on a Tl530 programmable controller. The intelligent I/O module used was the Texas Instruments programmable BASIC module. An IBM-PC was used as a host to the TIWAY I network. The Tl530 programmable controller was configured as a secondary on the network. The BASIC module was placed on the I/O rack of the programmable controller.

The limitations and assumptions made for the purpose of evaluation, and scope for further work are presented. In addition, economic considerations and additional capabilities of both the approaches are presented.