Programmable Logic Controller Code Research Articles

Specification, design, and implementation of logic controllers based on colored Petri net models and the standard IEC 1131. I. Specification and design

This work aims at designing and implementing logic control structures that allow a combination of the advantages of classical techniques for the development of programmable logic controller code and elimination of disadvantages such as the lack of formal validation. This paper introduces ordered color Petri nets in combination with some extensions as a modeling tool for logic controllers. The validation of both the model and the specifications of the logic control structures is then pursued through a structural analysis of the net. A special compiler that generates code according to the standard IEC 1131 is discussed. The modeling and implementation of a logic control system of a sector of a flexible assembly cell serves as an example.

A development environment for batch process control

A development environment and control modeling language is described which is designed to support the life-cycle of software development for programmable logic controllers (PLCs) in batch process manufacturing. The environment supports process design, logic specification and analysis, simulation, and automatic generation of PLC code from a high level control specification. The environment includes a set of dictionaries and rules, with associated editors, that permit specialization of the environment to particular manufacturing sites. It aims to standardize control code specifications, support reuse of specifications, allow inspection of specifications through simulation and reports, automatically translate the specification to code, and facilitate the long term maintenance of specifications. Its contributions are that it presents a control specification language for batch process control, a set of software tools to support PLC software development, and application of the environment to dairy processing.

Generation of optimal control policy for flexible manufacturing cells: A Petri net approach

For flexible manufacturing cells (FMCs), the major control problem is to determine the optimal part routeing and machines dispatching policy. In this research, we present a methodology for generating optimal operating strategies for FMCs. The methodology is built on two techniques: stochastic timed Petri net (STPN) and Markov decision process (MDP). The operating strategy devised with the proposed methodology is deadlock-free and provides the best performance given a set of system parameters (machines, parts, machining times, etc.). Generation of programmable logic controller (PLC) codes is greatly facilitated as the generated strategy can be mapped directly to a ladder diagram representing the PLC code. The objective of real-time optimal control could then be achieved with this type of controller. An example is provided to illustrate the methodology.

Generation of optimal operating strategies for robotic cells: a Petri net approach

Abstract This paper presents a methodology for generating optimal operating strategics for robotic cells. The methodology is built on two techniques: stochastic Petri net and Markov decision process. The operating strategy devised with the proposed methodology is deadlock-free and provides the best performance given a set of systems parameters (machines, parts, machining times, transportation times and so on). Generation of programmable logic controller (PLC) codes is greatly facilitated as the generated operating strategy can be mapped directly to n ladder diagram representation of the PLC code. In this paper, both the stochastic Petri net and Markov decision process techniques are discussed. An example is provided to illustrate the methodology.

A rule-based procedure for generating programmable logic controller code from graphical input in the form of ladder diagrams

This paper is concerned with a procedure for the automatic generation of code for programmable logic controllers. Input to the procedure is data from a graphical model of the discrete event dynamic system which is to be implemented. The model is constructed in the form of a ladder diagram at a graphics workstation. The data are held as Prolog tuples, and Prolog is used in the procedure to implement a rule base through which the data are mapped into the programmable logic controller code. Underlying the rule base are two methodologies. The first is a top-down decomposition of the ladder diagram to a level of three basic structures. The second is a bottom-up integration of code based on these structures into code for the whole system. An example is used throughout and the approach is shown to be effective.