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The paper begins by describing the present state of the art of graphic programming by means of ladder diagrams and control system flowcharts. The programming of sequential controls using the GRAPH programming language, which is under consideration by IEC for standardization, already constitutes the transition to graphics system configuring.

There is described a PC-development system providing for a producer-independent programming by bits and by words in different forms of display (ladder diagram, function-plan, Bool, assembly code) on a comfortable development system. The essential features whereof are the availability of library functions, reliance on existing standards, indexing possibility on all levels of speech, code generation from PC-independent interim code as well as re-indexing from target level to source level.

Publisher Summary This chapter describes the inclusive reactions and the few-body problems. The inclusive distribution is easier to measure than exclusive data. All that is needed is a single detector capable of measuring the particle and the inclusive distribution can be obtained by moving the detector around. Inclusive distributions had been measured for quite some time, under the name of single particle distributions. This distribution was a somewhat crude and average out quantity, given that a mixture of several final state channels could contribute to it, where every multiparticle channel is itself a difficult thing to analyses theoretically. A relativistic model where one can expect to make the sort of analytic continuation required is obtained by summing Feynman diagrams of a relativistic field theory model underlying the interaction of particles a, b, and c. A simple example would be to treat all particles as being described by a single scalar field interaction and sum the family of cross channel ladder. This is a natural extension of a well-known body of work in high-energy two-body scattering, where the set of ladder diagrams with an arbitrary number of rungs is summed.

The full parquet approach to many-body theory represents a self-consistent summation of Feynman diagrams for the two-body Green’s function, G 2, in terms of the bare interaction, V, and the one-body Green’s function, G. The parquet equations sum the reducible diagrams for G 2 which are generated from any initial set of irreducible diagrams. The full one-body G which is used in the construction process is obtained from the proper self-energy ∑ and the non-interacting Green’s function with the usual Dyson equation. One level of self-consistency is attained by constructing the ∑ from the G 2. The ∑ is obtained by closing off the G 2 with a V as shown in fig. 1.

This chapter describes the application of microprocessor-based industrial controllers in hierarchical and stand-alone configurations. Programmable systems have considerable advantages over hard-wired systems, such as the ease of configuration and modification with user-friendly graphic programming languages. After describing the architectures of standard microprocessors, three special architectures for programmable controllers are analyzed. The development of a “universal” programmable controller for both logic and fast closed-loop control is technologically possible and an innovative architecture for such a controller is described in detail. Trends in architectures for industrial controllers, the influence of software and the convergence of microcomputer and programmable controller architectures are discussed.

Programmable logic control (PLC) microprocessors are designed to take the place of hard-wired relay and contactor-control assemblies. Among the multiple advantages offereo are a wider scope of task adaptation and protective devices, rapid functional testing with less instrumentation in a small space: and greater reliability and endurance following therefrom. These merits can of course be put tc good use in the telecommunicatior supply sector; this has already been realised by the German Federal Post authorities. The necessary multicontrol functions are here represented by a schematic hardware layout, and a simplified flowchart of operational states. These introduce the requisite tasks of process control, and the programmable logic exercised by the central microprocessor. Operating experiences made in talcom power supply, and distribution engineering, are outlined.

The control system (CS) for the cryogenic arrangement of the DO Liquid Argon Calorimeter consists of a Texas instruments 560/565 Programmable Logical Controller (PLC), two remote bases with Remote Base Controllers and a corresponding set of input/output (I/O) modules, and a PC AST Premium 286 (IBM AT Compatible). The PLC scans a set of inputs and provides a set of outputs based on a ladder logic program and PID control loops. The inputs are logic or analog (current, voltage) signals from equipment status switches or transducers. The outputs are logic or analog (current or voltage) signals for switching solenoids and positioning pneumatic actuators. Programming of the PLC is preformed by using the TISOFT2/560/565 package, which is installed in the PC. The PC communicates to the PLC through a serial RS232 port and provides operator interface to the cryogenic process using Xpresslink software.

Because of the very large number of quality manufacturers of programmable controllers (PCs) in the United States, Europe, and Japan, most of whom do not offer a single product but rather a family of related products designed to satisfy the requirements of a large range of applications, selecting a system best suited to a given application has become increasingly difficult during the past several years. Consequently, efforts have been made to construct tabular comparisons of the capabilities and features of PCs. In one tabular system1, the following criteria are listed: Total system I/O Maximum discrete I/O Maximum analog I/O Relay ladder logic High-level language PID capabilities Motion control Documentation PC data highway Type of interface Scan rate Type and size of memory

A logic-based computer control system is in development at CEBAF. This Unix/C language software package, running on a distributed, hierarchical system of workstation and supervisory minicomputers, interfaces to hardware via CAMAC. Software aspects to be covered are ladder logic, interactive database generation, networking, and graphic user interfaces.

This paper describes a Fault Explanation System (FES) that aids in the diagnosis of failures in discrete event systems such as certain manufacturing processes. These systems are characterized by the use of programmable logic controllers (PLC) to control the systems. In addition PLC's also perform event logging. The event log (fault log) records exceptions which may be alarms, warnings or status reports. A major difficulty is that most of the alarms do not indicate real faults in the system; for example, a fault may cause an exception which indicates what the fault is, but this exception may also give rise to a number of other exceptions which are just side-effects. FES interprets and explains faults in the log based on a model provided by the ladder logic diagrams of the PLC. These explanations separate real exceptions from the kind of side-effects described above. Finally FES ranks explanations according to their plausibility.

In recent years, A.D. Jackson, A. Lande, and I have been approaching the many-body problem from the point of view of summing an important set of Feynman diagrams, the planar or parquet diagrams. It had long been recognized that the hypernetted-chain (HNC) variational theory approach and the summation of rings and ladders in perturbation theory were both dealing with diagrams of very similar topological structure. Early work by Sim, Buchler, and Woo [1] showed that the optimized hypernetted-chain (HNC) variational theory for bosons summed all ring and ladder diagrams exactly and in addition generated terms whose structure was that of other legitimate diagrams. Neither the numerical factors nor the diagrams generated this way were identified. Ref. [2] showed that the diagrams generated by the optimized HNC theory were a subset of the parquet diagrams and in general were not generated with the right numerical factors. Roughly speaking, the boson parquet theory sums ring diagrams in which there can be ladders between bubbles and ladder diagrams in which the rungs of the ladders can be chains of bubbles. These two types of diagrams are embedded in each other in a self-consistent way. A first effort was made in this work to generate an approximate sum of parquet diagrams. For the energy of liquid 4He, the results were comparable to those obtained from optimized Jastrow theory; the corresponding liquid-structure function was reasonable except for the behavior at small k.

Programmable logic controllers (PLCs) are commonly programmed using relay ladder logic. There are many disadvantages to this approach. The state transition diagram affords a systematic means of providing precise and unambiguous specification while at the same time yielding a good system overview for ease of troubleshooting and maintenance. Computer aided logic design techniques help to automate the process of relay logic design for the state transition diagram. A software package which runs on an IBM PC/compatible machine has been developed to automatically transform the state diagram specification into relay ladder logic and the associated (PLC dependent) source code.

The advent of relatively high speed computer graphics systems offers an attractive means by which the designer can more effectively perform his tasks. This paper describes an approach in designing and analysing logic control systems through the use of a VAX 11/780 mini-computer equipped with interactive graphic displays. The software primarily includes a logic circuit simulation program with various application processors which provide a communication link between the graphics, the data base and the simulation program itself. The system allows the user to create interactively on a colored graphic screen, a logic ladder diagram; the resulting information will be carried by the data base which provides necessary input to run the simulation program. The latter accepts logic input conditions imposed by the user to the control circuit then simulates appropriate component logic switchings and updates the data base accordingly. The user can also introduce various types of abnormal operating conditions into the system in order to verify the capability of the control circuit to satisfy the process safety requirements.

Sooner or later (usually sooner) the HVAC system designer comes to the necessity for starting and stopping electric motors for fans, compressors, boilers, pumps and accessories. And, all too often, he feels that these things are the responsibility of the electrical engineer. So, having graciously informed said electrical engineer of the location and size of these motors, the system designer goes away satisfied that he has done his part.

A diagramming system has been developed to assist in interpreting dual chamber pacemaker electrocardiograms. The system is based on the ladder diagram principle but uses two separate ladders, one for the ECG allowing proper representation of atrial A-V and ventricular activation, and a second ladder diagram below it for pacemaker events. The system is applicable to all current single and dual chamber pacing modes and is easy to draw. The ladder diagram allows the logical sequence of timing events to be easily illustrated, and pacemaker malfunction becomes clearly recognizable as a conflict between the ECG events ladder and the pacemaker timing ladder. The system is easy to apply and may eventually prove suitable for automatic generation by computer utilizing sophisticated pacemaker telemetry.

Sequential control circuits, typical of industrial applications, can often be of a complex nature. Synthesis of such systems may be difficult and time consuming when using intuitive methods (ladder diagram), or rigorous but classical methods, (Karnaugh, Huffman etc.). The latest development of tools suitable for sequential evolution and its graphical representation, the increasing availability of integrated circuits and microprocessor kits make it attractive to utilise them for the above task. The goal of this paper is to present a local experience realised at the “Ecole Normale Superieure de l'Enseignement Technique de TUNIS” in the field of logic systems design. The method introduced has been developed in order to obtain a systematic and simple systhesis without constraints. In order to do this, designers are provided with a methodology and tools allowing the synthesis of logic controllers with a low cost techniques. Interpreted PETRI nets are utilised as a graphical means for the description of a given problem. The model obtained is then transcribed into logic expressions depending on the implementation. Finally, the implementation can be achieved using either hardwired or programmed systems. This synthesis method is taught in our teaching institution for several years, the results are satisfaying. In order to simulate and to control industrial applications, universal hardwired sequencers and programmable controllers have been realised in our laboratory. An application example is given to illustrate the different steps of the synthesis method.

In recent years, the use of the digital computer in process monitoring and control applications has expanded to include many production areas outside the process industries (chemical production, oil refinery operations and steelmaking). One of the important growth areas has been in discrete parts manufacturing: metal machining, pressworking, electronic components manufacturing, assembly, and so on. Many of these applications are limited to computer monitoring duties, but in other cases the potential has been demonstrated for using the computer for process control.

The paper sets out to identify application areas in processing industries in which microprocessors and programmable controllers (PC) may be used selectively to automate the process lines. Comparative advantages of these two systems are discussed. In particular automation of a steel sheet classifier which uses two microprocessor based systems is described. Other examples of PC based automation are briefly described which bring out the salient points which are foremost in the system designer’s mind when considering automation of any plant, particularly those requiring fast response from the controller.

Two approaches to the problem of calculating the binding energy BΛ of a Λ-particle in nuclear matter are discussed. The first method is via the Bethe- Goldstone equation for the problem in the independent-pair approximation. The second method is a Green-function formulation which sums the ladder diagrams for the self-energy of the Λ-particle. Using an S-wave separable potential fitted to the ΛN scattering data, exact analytic expressions for BΛ are found for both methods and compared. The relation between the two approaches is discussed and it is shown how to extend the Green-function formulation to include the effect of the higher-order cluster diagrams, contributing to the Λ-particle self-energy, in a consistent manner. It is pointed out that this approach provides a more systematic formulation than the usual extended Bethe-Goldstone approach. The model ΛN hard core problem is also investigated in the Green function approach in an appendix: the ground-state energy is rederived and expressions are found for the effective mass and damping of the Λ-quasi-particle up through terms of order (kFa)2.

A wide variety of industrial systems are controlled and supervised by programmable logic controllers (PLCs). Although the PLC is particularly well adapted to problems requiring sequential control or the verification of interlocks prior to further actions taking place, they are very poor at supporting diagnostics when problems occur. On the other hand, the PLC does contain valuable information to assist with diagnosis though, it is just very difficult for an engineer or operator to understand it directly. This paper describes the automatic development of a troubleshooting system which can be build using the precise and deterministic knowledge embedded within the PLC and extending it with heuristic knowledge.

The acceptance of formal methods in industry is a challenging task mainly due to difficult learning process and the lack of the tools and methods helping control engineer to interpret the results of formal verification procedure. We model existing source code of the controller and controller related information (controller model) along with controlled object (plant model) and verify modeled system by means of model-checking. This paper focuses on the issues related to controller and plant modeling. Ladder logic modeling is discussed along with the problems related to the plant modeling

The paper presents a method for hierarchical description of control algorithms with their partitioning into tasks that are executed sequentially and those that run concurrently. The proposed method is based entirely on components available in the Ladder Diagram (LAD) language, and can be considered as an alternative to the Sequential Function Chart (SFC) diagrams. In addition, an architecture for a reconfigurable logic controller is proposed, which is capable of executing the control program combined hardware and software tasks. For that purpose the mechanism of dynamic partial reconfiguration of programmable gate arrays (FPGA-s) is used. This makes possible to download to the programmable structure only those tasks, which are currently required by the running control algorithm. Such a hardware implementation of the controller enables effective execution of concurrent control tasks by parallel operation of the control processing units. Finally, a proposed controller architecture allows using a programmable device of a reduced size, and this makes the solution more cost-effective.

The paper presents developed synthesis methodology of a hardware implemented reconfigurable logic controller from multiple languages incorporating ladder diagrams, instruction list and sequential functional chart according to IEC61131-3. It is focused on the originally developed a high performance computation model based on properly defined variable access. The method address synthesis process of logic and arithmetic operations. Presented approach is able to synthesize not only basic constructs of languages but also complex modules like timers and counters. The paper acquaint with the compilation of considered languages and complex modules into intermediate form suitable for logic synthesis process according to developed analysis, translation and mapping methods. The data flow graph has been chosen for intermediate representation of a program. An original enhancement of the DFG with attributed edges and specific nodes has been described. It allows for efficient representation and processing of logic and arithmetic formulas. The set of compilation algorithms that preserve effects of serial execution order and offer obtaining massively parallel processing unit are presented.

The author describes two complementary software programs, called PROLOC and AILISTD, which make up a high-level computer-aided design package that transforms functional specifications into relay ladder design for direct implementation in a programmable logic controller (PLC). AILISTD uses artificial-intelligence techniques to transform the functional specifications into a state transition diagram (STD) representation. PROLOC then translates the STD specifications into relay ladder design for programming into a PLC. A laboratory example involving a liquid level control system illustrates the use of both programs. >

SFC (sequential function chart), which is a graphical tool for control logic and can also represent the order for events to be controlled explicitly, has been presented as a programming language of sequential control. Since even a nonspecialist can understand SFC, it will be the main tool of sequential control. In spite of this excellent characteristic of SFC, ladder diagrams (LD) are still used in various industrial applications. In this paper, we regard LD and controlled plant as one closed loop, and propose the algorithm for picking up order of events based on the closed-loop system. We try to model the plant by means of temporal logic.

As automated manufacturing systems become more complex, the need for an effective design tool to produce both a high level discrete event control system (DECS) and a low level ladder logic implementation, becomes increasingly more important. Petri nets represent the most effective method for the design of such DECSs. The conversion of such Petri net controllers into ladder logic has been greatly simplified through the advent of the token passing logic methodology. The new technique provides a straightforward but powerful method by which to implement ladder logic code. In this paper the fundamental T-Timed Petri net structures and their associated ladder logic equivalents are described. Finally, the design of a DECS for a manufacturing system is considered. A heuristic Petri net controller is developed for the manufacturing system, and then the methodology is used to derived structured ladder logic code.

Existen diferentes lenguajes de programación de Controladores Lógicos Programables (PLC), el más común de ellos es el lenguaje de programación gráfico para autómatas programables llamado LADDER. Sin embargo, el lenguaje LADDER no es amigable en programas que requieren de cálculos de ecuaciones matemáticas, por ejemplo, el cálculo del volumen de un tanque en un control de nivel. Lenguajes alternativos como el Lenguaje de Control Estructurado (SCL) son menos estudiados dada su complejidad y poca popularidad en la pequeña y mediana industria. En este artículo se compara los resultados del lenguaje de programación LADDER y el lenguaje SCL generado mediante la herramienta Simulink® PLC Coder de MATLAB® tomando como caso de estudio el cálculo de volumen de un tanque. Finalmente, este trabajo demuestra que la herramienta Simulink® PLC Coder presenta una alternativa de desarrollo más eficiente.

Signal interpreted Petri nets (SIPN) show good properties in modeling and analyzing control algorithms. With SIPN, logic controllers are modeled by places-setting output signals-and transitions between those places-depending on Boolean functions of input signals. This model has interesting dynamics: Firstly, several transitions can fire simultaneously. Secondly, there can be iterated firing of transitions before a new stable marking is reached. In standard PLC programming languages, there is no direct means to implement these dynamics. In this contribution a method for the generation of transparent PLC code from SIPN is presented (using instruction list or ladder diagram). The code is transparent because there is a one-to-one correspondence between SIPN elements and code segments. A new analytical method to guarantee the correct dynamics of the implemented code is presented and compared to existing approaches. The new method results in a special ordering of the code segments. The presented analysis of the SIPN shows if a transition t/sub a/ can fire in an iteration after transition t/sub b/. In this case, the code segment describing t/sub b/ has to be processed prior to the one of t/sub a/. A solution for the case, where the analysis results in an impossible ordering is also presented.

EIGHTY years ago, Jevons, then professor of logic at Owens College (now the University of Manchester), built a machine which could perform logical inference by mechanical means1. Other similar machines have been built since then. With the present interest in electrical and electronic computing machines, it seemed worth while to construct a logical machine using modern electrical methods, at the same time basing it on the present-day logical technique of truth tables rather more explicitly than had been done by Jevons.

Introduction A computer-based system for analyzing complex cardiac rhythms is being developed in our laboratory. The system analyzes rhythms by adapting and simulating one or more semi-quantitative electrophysiologic models based on a sequence of events (P waves, QRS complexes, His bundle potential, etc.) on an event-by-event basis. The electrophysiologic model developed for the system can represent anatomies consisting of up to 4 accessory pathways, up to 3 AV nodal slow pathways, and 1 Mahaim pathway. We hypothesized that this system can (1) generate the correct electrophysiologic model(s) based on the observed events, (2) correctly differentiate between AV Nodal Reentrant Tachycardia (AVNRT), AV Reentrant Tachycardia (AVRT), and Atrial Tachycardia (ATACH) based on intracardiac electrogram data obtained during ventricular extrastimulus pacing protocols, and (3) generate ladder diagrams describing the identified rhythm mechanisms. Methods Typical cases were identified for each of the desired rhythms (AVNRT, AVRT, and ATACH). Using software written in our lab, the cases were annotated to extract wave timing and morphology from the body-surface electrocardiogram and wave timing of the high right atrial. His bundle, and right ventricular intracardiac electrograms. Due to the anatomic complexity underlying reentrant tachyarrhythmias, we developed novel algorithms for enumerating the complete set of conduction paths through complex electrophysiologic models. We also developed the logic necessary for reasoning with multiple model paths and simultaneous activation of anatomically distinct model regions. The system was developed in C on a UNIX workstation and runs on UNIX workstations or IBM PC-compatible computers. Results In all cases, the system (1) generated the correct set of electrophysiologic models, (2) eliminated or supported the appropriate models (i.e. rhythm mechanisms) based on the ventricular extrastimulus, and (3) generated ladder diagrams describing the rhythm mechanisms. Conclusions This is the first report of a computer-based system capable of deriving differential diagnoses with supporting ladder diagrams from intracardiac electrogram recordings. This demonstrates the potential for automatic analysis of complex rhythms by computer-assisted analysis of intracardiac electrograms. This system may be useful in the clinical electrophysiology laboratory by assisting physicians with the enormous amount of data generated during the typical electrophysiology study.

Program obtainable from: CPC Program Library, Queen’s Oppenheimer approximation. University of Belfast, N. Ireland (see application form in Method of solution this issue) The diagrammatic many-body perturbation expansion is employed through third-order in the energy and first-order Computer: IBM 360/91; Installation: The Johns Hopkins in the wavefunction, including all many-body effects that University Applied Physics Laboratory arise. The calculations areperformed within the algebraic approximation [1] in whicheigenfunctionsare parameterOperating system: ASP izedby expansion in a finite set of basis functions. Computer algorithms are presented for the evaluation of second-order Programming language: FORTRAN IV energies; overlap integrals over the first-order perturbative wavefunction; and third-order particle--particle andhole—hole High speed storage required: 200 kilobytes ladder diagrams.

This monthly series of electrocardiograms (ECG) for physicians interested in electrocardiography will be presented to demonstrate basic electrocardiographic and electrophysiologic principles. Initial issues will provide a foundation upon which we shall build as more complex arrhythmias are discussed. Occasionally, we will include pertinent references and briefly mention therapy when appropriate. The ladder diagram will be employed frequently to depict depolarization and conduction schematically. Straight lines drawn on a tiered framework beneath an ECG trace represent electrical events occurring in the various cardiac structures (Fig 1). Certain features of the ladder diagram need further explanation. Since the ECG, and, therefore, the ladder diagram, record electrical activity against a time base, conduction is indicated by the sloping lines of the ladder diagram in a left to right direction. A less steep line depicts slower conduction; a short bar drawn perpendicular to a sloping line represents blocked conduction (Fig 2). On occasion, activity