Sequential Function Chart Research Articles

METHOD OF PROTOTYPING CONTROL UNITS BASED ON THE OPENPLC APPLICATION

The problem of designing control devices based on programmable logic controllers (PLCs) is their high cost and, as a rule, unavailability at the initial design stage. The purpose of the research is to reduce the time and cost of designing the system by creating prototypes of control units with the software implementation of control algorithms in the languages of the MEK 61131-3 standard and the execution of programs in the Arduino board. The research method consists in the decomposition of project models of operating and control automata of the control device and their implementation in the software environment of the OpenPLC application in the form of program organization components (POU) in Ladder Diagram, Function Block Diagram, Sequential Function Chart and Structured Text languages. The result of the study is a method of creating typical POU operating and control automata of the control system, which are executed in the Arduino board. An example of the application of the proposed methodology for the design of a prototype of the facility's temperature control system is given. The developed prototype was tested using a logical PLC and a physical prototype, which confirmed their functional compliance with the original and a reduction in the cost of the equipment by at least an order of magnitude.

Investigating the graphical IEC 61131-3 language impact on test case design and evaluation of mechatronic apprentices

Abstract Mechatronic on-site technicians are responsible for maintenance and thus adequate testing of automated production systems. Hence, they must derive test cases from the IEC 61131-3 control code, which requires systematic testing skills. But despite the industry’s high demand for such skills, testing is not established in mechatronic apprentices’ educational curriculum. For the design of a teaching strategy for mechatronic apprentices on testing, this paper investigates the impact of the IEC 61131-3 language on test case design and evaluation. Comparing Sequential Function Chart (SFC) and Function Block Diagram, a trend towards SFC in apprentices’ self-perceived and real competence is shown.

Realization of Control System of Automatic Welding Machine for Air Conditioning Flange Based on CANopen

The principle of automatic welding machine (AWM) for air conditioning flange is introduced. The architecture of the control system of AWM realizes the multi spindle linkage control. The communication between PLC and servo driver is built based on CANopen protocol, and the communication between PLC and touch screen is set up based on Modbus RTU protocol. To meet the welding machine spindle coordination control requirements, the PLC program is designed by Delta ISPsoft programming software, and simplified by the application of sequential function chart (SFC) and function block. The human machine interaction (HMI) is developed by Xinjie Touchwin. Linear interpolation algorithm (LIA) is used to prevent the welding defects on the air conditioning flange corner thus it improves the welding quality and realizes the straight path of welding torch from the original to starting welding point and from the end welding point to the original simultaneously. The AWM for air conditioning flange can replace the manual welding and has a broad application prospect in many areas.

Reconfigurable Logic Controller—Direct FPGA Synthesis Approach

Programmable logic controllers are commonly used in automation systems. Continuously growing demands result in the growth of control program complexity. The classic approach, based on programmatic serial-cyclic execution, results in an unacceptable extension of response time. To overcome long response time massive parallel program execution is proposed. It utilize direct in hardware program implementation in field programmable devices. The paper brings a formal method of representing control programs using flow graphs and enabling single cycle computations. The developed method accepts ladder diagrams (LD) and sequential function charts (SFC), according to IEC61131-3 standard requirements. It is capable of handling logic and arithmetic computations, enabling its hardware mapping. The intermediate form is optimized using flow graph representation and BDDs for analyzing logic dependencies. The BDD representation of logic dependencies enables direct mapping to lookup tables of a selected FPGA family. All the above steps deliver high-performance and direct hardware implementation of the control program given by standard languages. The controller response time is short, predictable, and independent from logic conditions during program execution.

Custom-tailored clone detection for IEC 61131-3 programming languages

Automated production systems (aPS) are highly customized systems that consist of hardware and software. Such aPS are controlled by a programmable logic controller (PLC), often in accordance with the IEC 61131-3 standard that divides system implementation into so-called program organization units (POUs) as the smallest software unit and is comprised of multiple textual (Structured Text (ST)) and graphical (Function Block Diagram (FBD), Ladder Diagram (LD), and Sequential Function Chart(SFC)) programming languages that can be arbitrarily nested.A common practice during the development of such systems is reusing implementation artifacts by copying, pasting, and then modifying code. This approach is referred to as code cloning. It is used on a fine-granular level where a POU is cloned within a system variant. It is also applied on the coarse-granular system level, where the entire system is cloned and adapted to create a system variant, for example for another customer. This ad hoc practice for the development of variants is commonly referred to as clone-and-own. It allows the fast development of variants to meet varying customer requirements or altered regulatory guidelines. However, clone-and-own is a non-sustainable approach and does not scale with an increasing number of variants. It has a detrimental effect on the overall quality of a software system, such as the propagation of bugs to other variants, which harms maintenance.In order to support the effective development and maintenance of such systems, a detailed code clone analysis is required. On the one hand, an analysis of code clones within a variant (i.e., clone detection in the classical sense) supports experts in refactoring respective code into library components. On the other hand, an analysis of commonalities and differences between cloned variants (i.e., variability analysis) supports the maintenance and further reuse and facilitates the migration of variants into a software productline (SPL).In this paper, we present an approach for the automated detection of code clones within variants (intra variant clone detection) and between variants (inter variant clone detection) of IEC61131-3 control software with arbitrary nesting of both textual and graphical languages. We provide an implementation of the approach in the variability analysis toolkit (VAT) as a freely available prototype for the analysis of IEC 61131-3 programs. For the evaluation, we developed a meta-model-based mutation framework to measure our approach’s precision and recall. Besides, we evaluated our approach using the Pick and Place Unit (PPU) and Extended Pick and Place Unit (xPPU) scenarios. Results show the usefulness of intra and inter clone detection in the domain of automated production systems.

Software‐guided Microfluidic Reaction Calorimeter Based on Thermoelectric Modules

AbstractA software‐guided, continuous reaction calorimeter based on thermoelectric modules for direct heat flux measurements is presented. Sensors and actuators of the calorimeter's setup are implemented within a lab automation system, which enables the automated calibration of the heat flux sensors and investigations of chemical reactions through sequential function charts. Functionality of the calibration is shown by heat transfer experiments. Additionally, the calorimeter's performance is demonstrated by good agreement of conducted neutralization experiments with literature data.

Synthesis and Validation of Operating Procedures Based on Untimed Automata

To facilitate efficient procedure synthesis, the extended finite automata are adopted in this work to model all components in a chemical process. The intended operation is divided into several stages and each characterized with a set of unique features, e.g., stable operation, condition adjustment, material charging and/or unloading, etc. The control specifications of every stage should then be stipulated accordingly and also described with automata. The observable event traces (OETs) embedded in this system can be produced by synchronizing all aforementioned automata. The candidate operating procedures are summarized with sequential function charts (SFCs) on the basis of these OETs. The commercial package ASPEN Plus Dynamic has been used to validate these SFCs in simulation studies.

Control of Hydraulic Pulse System Based on the PLC and State Machine Programming

In this paper, we deal with a simple embedded electronic system for an industrial pneumatic–hydraulic system, based on a low-cost programmable logic controller (PLC) and industrial electronic parts with 24 V logic. The developed system is a hydraulic pulse system and generates a series of high-pressure hydraulic pulses with up to a max. 200 bar output pressure level and with up to a max. 2 Hz output hydraulic pulses frequency. In this paper we are describing requirements, the concept of the embedded control system in a diagram, security features and its industrial network connectivity (CAN bus, MODBUS). In description of the software solution we describe the implementation of the program threads approach in this low-cost PLC. The PLC programming with threads generate two layers of services—physical and application layer, and as a result, the threads create the main control state machine. In conclusion, we describe the calibration method of the system and the calibration curves. For further study we offer readers the full programming code written in sequential function charts to be used as PLC language. The cost of the described industrial networked control system with industry standard optoelectronic insulated interfaces and certified industrial safety relay does not exceed €1000 Euros.

Structural Concolic Testing for Sequential Function Chart

Graphical programming languages allow for well structured software and support comprehensibility and maintainability of the code. As for industrial applications, Sequential Function Chart(SFC) is a popular graphical language and was introduced by the IEC-61131-3 standard. Although providing powerful structuring elements that programmers can use to write better software, those elements are largely dropped when translating the software to a representation required for the application of formal methods. Even in widely used development-tools like CODESYS, SFCs are internally translated to the textual language Structured Text, coming from the same standard. This approach preserves the semantics needed for simulation, but can introduce significant overhead that impedes the application of formal methods, e.g. Concolic Testing, which is the focus of this work. To this end, we propose a novel Concolic Testing approach that utilises the structure of SFC in order to overcome the obstacles that keep traditional techniques from achieving high test-coverage in a reasonable amount of time. We compare our results to two approaches that work on a textual representation of the program.

SISTEM OTOMASI PADA MODUL PROCESSING DENGAN MENGGUNAKAN SEQUENTIAL FUNCTIONAL CHART

Abstract: Automation is a technology that can be used to implement an instructional process or an automatic procedure. In this framework that has been using an instructional program that combined with a control system to process an instruction or commands. This processing module is a part of the automation which checking a process simulation of hollow and not hollow objects, then a PLC is use to control the process as designed be needed to control all of the working processing modules systems works. working system, a programming language that easily to be understood is needed such as functional block diagram (FBD) is use to program a plc system which functional block diagram (FBD) is a method that can describe a function between input and output variable, in FBD there is a Sequential Function Chart method (SFC ) which control the program sequential activity. So this research discusses the control of processing module which based on FBD programming language by using the SFC method.

Semantic Modelling of Hybrid Controllers for Robotic Cells

Programmable Logic Controllers (PLCs) play an important role for integration of hardware and software in industrial robot cells. In this paper we propose a semantic grounding of the Sequential Function Charts (SFC) notation for specification of PLC programs. Our semantic grounding is expressed in the OWL semantic language and forms part of our semantic robot framework, called KIF (Knowledge Integration Framework). KIF is a set of ontologies and associated tools to ensure interoperability between heterogeneous equipment making up a robot cell. We also present a tool set for manipulating SFC instances stored in RDF triple stores reachable through the RDF4J framework. The semantic grounding and tool set are evaluated in a teaching-by-demonstration experiment in a small parts assembly setup featuring a collaborative industrial robot, ABB YuMi, where the tool set is used to create and execute SFC descriptions on-the-fly based on data from human demonstrations.

Evaluation of Selected Control Programming Languages for Process Engineers by Means of Cognitive Effectiveness and Dimensions

Different programming languages can be used for discrete, abstract and process-oriented programming. Depending on the application, there exist additional requirements, which are not fulfilled by every programming language. Flexible programming and maintainability are especially important requirements for process engineers. In this paper, the programming languages Activity Diagram, State Chart Diagram and Sequential Function Chart are compared and evaluated with regard to these requirements. This evaluation is based on the principles of cognitive effectiveness and cognitive dimensions. The aim of this paper is to identify the programming language suited best for controlling sequential processes, e.g. thermomechanical or batch processes.

Automata-based operating procedure for abnormal situation management in batch processes

“Abnormal situation management” (ASM) in general refers to the various tasks required for online fault diagnosis and also hazard mitigation. Although quite a few ASM-related studies have already been carried out in the past, none of them addressed the wide range of issues consistently and rigorously with the same modeling tool. An automata-based strategy is therefore proposed in this work to synthesize all operating procedures needed for diagnostic tests and also other emergency response operations in the batch processes. The proposed model building techniques are suitable not only for characterizing all components in any given process, but also for representing the operation targets of all ASM tasks. Finally, notice that every resulting procedure can be readily expressed with an implementable sequential function chart (SFC).

Applying Model Checking to Industrial-Sized PLC Programs

Programmable logic controllers (PLCs) are embedded computers widely used in industrial control systems. Ensuring that a PLC software complies with its specification is a challenging task. Formal verification has become a recommended practice to ensure the correctness of safety-critical software, but is still underused in industry due to the complexity of building and managing formal models of real applications. In this paper, we propose a general methodology to perform automated model checking of complex properties expressed in temporal logics [e.g., computation tree logic (CTL) and linear temporal logic (LTL)] on PLC programs. This methodology is based on an intermediate model (IM) meant to transform PLC programs written in various standard languages [structured text (ST), sequential function chart (SFC), etc.] to different modeling languages of verification tools. We present the syntax and semantics of the IM, and the transformation rules of the ST and SFC languages to the nuXmv model checker passing through the IM. Finally, two real cases studies of the European Organization for Nuclear Research (CERN) PLC programs, written mainly in the ST language, are presented to illustrate and validate the proposed approach.

Microcontroller implementation of lookup table-based control functions with special emphasis on sequential control according to IEC 61131-3

This paper covers the possibility of retraining for those electrical engineering undergraduate students already having some basic digital knowledge. It gives a solution to lead the students to the microcontroller-based program control of complex industrial tasks with a uniform approach. It presumes that the students are familiar with combinational and sequential logic, know the hardware and software basics of microcontroller systems, and have experience in the use of C program language. Building upon these, it presents a lookup table-based control description system for simple combinational solutions to complicated sequential controls. It separately details this kind of implementation of sequential controls according to the Sequential Function Chart (SFC) program language corresponding with the standard IEC 61131-3. For the processing of the tabular data describing the controls, it provides interpreter programs independent from the current tasks. Teaching outcomes are discussed in the final part of the paper.

A Petri Net Diagnoser for Discrete Event Systems Modeled by Finite State Automata

We propose in this paper a Petri net approach to online diagnosis of discrete event systems (DESs) modeled by finite state automata. The diagnosis method is based on the construction of a Petri net diagnoser (PND) which is constructed in polynomial time and requires less memory than other methods proposed in the literature. We also present methods for the conversion of the PND to both sequential function chart and ladder diagram for implementation on a programmable logic controller (PLC). Implementation issues are also addressed in the paper.

PENGENDALIAN MODUL ROTARY HANDLING STATION BEBASIS SEQUENTIAL FUNCTION CHART (SFC)

Abstract: The system used in this day and age has made progress in its operations. In industry itself many use automated systems that only require a small operator to run a tool because it saves time, and safety is guaranteed. In this time the tool discussed Handling Station Rotary pneumatic system uses motion to move this tool. So that the tool can be moved according to plan also required the "brains" to run this tool. Where the brain is a Program Logic Controller (PLC) to save a program that has been created in order to move the tool. Program created in this thesis using Sequential Function Chart (SFC) using Zelio Soft application. For components that are needed in this form of censorship tool as a reader, selonoid as air regulator to move from such a device.

PENGENDALIAN MODUL PROCESSING BEBASIS SEQUENTIAL FUNCTION CHART (SFC)

Abstract: Automation is a technology that can be used to implement an instructional process or an automatic procedures. In this framework that has been using an instructional program that combined with a control system to process an instruction or commands. This processing module is a part of the automation engine which checking a process simulation of hollow and not hollow objects, then a PLC is to be needed to control all of the working processing modules systems which system works as you want. To control a working system, a programming language that easily to be understood is needed such as functional block diagram (FBD) which functional block diagram (FBD) is a method that can describe a function between input and output variable, in FBD there is a Sequential Function Chart method (SFC) which control the program sequential activity. So this research discusses the control of processing module which using FBD programming language by using the SFC method.

Automata generated test plans for fault diagnosis in sequential material- and energy-transfer operations

Hardware failures are inevitable random events that occur in the operation life of a batch chemical plant. Based on the piping and instrumentation diagram (P&ID) of the given process and the sequential function chart (SFC) of its normal operating procedure, a system automaton and the corresponding “diagnoser” can be built to identify all observable fault propagation traces and, also, their root cause(s). Since the fault origin(s) of a trace may not be unique, there is a need to develop a nonconventional means to further enhance diagnostic performance. For this purpose, a novel approach is proposed in this study to synthesize the test plan of every undiagnosable trace on the basis of discrete-event system (DES) theory. In particular, all components at the failure-induced initial states and the required control specifications are first modeled systematically with automata and, then, an optimal supervisor (test plan) can be assembled accordingly so as to achieve the operation goal of differentiating the fault origins as much as possible. This proposed strategy has been tested successfully in a series of examples and the results of selected case studies are reported in this paper.

The Design of Control System for Motion Platform Based PLC

In this paper, a new-style platform control system with three degree of freedoms: up-down motion, left-right rolling and front-rear pitching is designed ,and also its composition, operating principle and soft design method are introduced. The system is driven by air cylinder and consists of FX series PLC, AD module, DA module, proportional valves , sliding rheostats and so on. Among these modules, sliding rheostats works as a feedback component to comprise a closed loop. Furthermore, to ensure the high positioning precision, thePIDalgorithm is applied. In addition, to control the motion flow reliably, the ladder logic diagram of the turn-off prior to turn-on is used to replace Sequential Function Chart. Experiments show that the motion platform is steady and safety when the proportional valves and directional valves are controlled by PLC.