Declarative specification of system independent logic controller programs

Programmable logic controllers (PLC) as the backbone of industrial automation adapt to each subsequent wave of technology. This is still true today, almost six decades after the first Modicon 084 programmable controller developed for General Motors. Innovations such as artificial intelligence, cloud and edge computing, IIoT, 5G networks, augmented and virtual reality are penetrating all possible areas of industry, and PLC controllers are no exception. Equipped with a modern functional arsenal, these compact industrial computer systems become the basic building block of intelligent automation, digitalization and Industry 4.0, enabling dynamic regulation and management of industrial processes based on data via real-time feedback. The global market for PLC systems is estimated at US$ 12.2 billion in 2024. It is expected to exceed 15 billion dollars by 2029. PLC controllers, which traditionally serve as the basis of process and discrete industrial automation, are becoming more widespread today adopting the principles of Industry 4.0 in various sectors. The impact on the increase in the need for them is the increased application of industrial robots in the automotive, electrical engineering and other industries. The industrial robotics sector is among the leading contributors to development of PLC systems and is becoming a key driver of the further development of the programmable controller market, and forecasts are that this trend will continue with the development of increasingly widespread robotization in factories around the world. According to the data of the IFR (International Federation of Robotics) from 2024. almost 4.3 million robots are already in operation.

Purpose: to analyze the possibilities of using programmable logic controllers (PLC) in water distribution management in the Don Main Canal. The work is an analytical study based on the principles of automation and optimization of water resources control. Discussion. The architecture of the control system, including programmable logic controllers, network modules and water level sensors in the main canal is discussed. The main attention is paid to justifying the use of PLC in the design and development of a water distribution control system, which allows control and regulate the water level in the channel using the upstream control scheme. The software offers possibility for monitoring water parameters, calculating optimal values and automatic adjustment of control signals. The advantages of using PLC in water distribution control system, including high flexibility, reliability and the possibility of easy integration with other systems are also analyzed. The methods of PLC setting, regulator optimization and energy management to achieve efficient and economical water resources management are described. The research confirms the effectiveness and applicability of using the programmable controllers in water distribution management system in the Don Main Canal. Conclusions: the results obtained make it possible to increase the efficiency of water resources use, reduce energy consumption and ensure stable control of water level in the irrigation canal.

A methodology for automatic generation, formal verification and implementation of safe PLC programs for power supply equipment of the electric lines of railway control systems

Traffic lights are commonly used in the intersection in urban areas nowadays. In fact a network of the traffic lights regulating the urban vehicle can be viewed as a complex discrete-event system (DES). It is proved that Petri nets are one of the methodologies for modeling, analyzing and controlling on DES. A new approach via programmable logic controller (PLC) and Petri net synthesis is proposed in this paper. Firstly, we described the typical urban traffic lights control using Petri nets. Having compared with three methods for Petri nets realization, the best implementation method of the traffic lights control system was one which made with the PLC. The sequential function chart (SFC) of the PLC system is also given in the thesis. The result shown that the method has many advantages at improving flexibility and troubleshoots of system and reducing the difficulty in its realization.

Petri nets have been extensively applied for specification, design, verification, performance evaluation, and simulation of discrete event control systems (DECS). The usual way to verify the dynamic behaviour of DECS design is to employ a process-based model, which proves to be impractical in application because the process-based model does not usually fully correspond to the control programming behaviour. This paper proposes a sensor-based stage Petri net (SBSPN) to represent a programmable logic controller (PLC) stage logic diagram (LD) for discrete-event control design. The new technique is able to simplify the modelling process of the complex PLC program without considering the interlocking problem within the ladder diagram. An illustrated example is used to explore the new methodology. The proposed method contains the power and flexibility of the Petri net analysis prior to the PLC implementation. It is believed that this technique is significant for industry practice.

Programmable Logic Controllers (PLCs) are widely used for control and automation of machines and processes, so the quality of PLC software has a direct impact on production efficiency. This paper describes a PLC program for a food production line that was completely rewritten using a different software architecture and framework. The PLC hardware and the production line equipment were not changed, so this project provides an opportunity to quantify the impact of different PLC software architecture on production efficiency. The average number of cases of products produced per production hour during the first ten months with the new program was 6.1% higher than the average during the previous ten months with the old program. PLC software, unlike most other software, is often used by the end-user for troubleshooting. In this case, a relatively simple architecture and framework that favors the end-user significantly improved production efficiency over a more sophisticated architecture and framework that favors the software developer. Suggestions for further research on software architecture and framework are given.

Automatic test of safety specifications for PLC programs in the Oil and Gas Industry

This paper deals with a "digital twin" (DT) approach for processing, reprocessing, and scrapping (P/R/S) technology running on a modular production system (MPS) assisted by a mobile cyber-physical robotic system (MCPRS). The main hardware architecture consists of four line-shaped workstations (WSs), a wheeled mobile robot (WMR) equipped with a robotic manipulator (RM) and a mobile visual servoing system (MVSS) mounted on the end effector. The system architecture integrates a hierarchical control system where each of the four WSs, in the MPS, is controlled by a Programable Logic Controller (PLC), all connected via Profibus DP to a central PLC. In addition to the connection via Profibus of the four PLCs, related to the WSs, to the main PLC, there are also the connections of other devices to the local networks, LAN Profinet and LAN Ethernet. There are the connections to the Internet, Cloud and Virtual Private Network (VPN) via WAN Ethernet by open platform communication unified architecture (OPC-UA). The overall system follows a DT approach that enables task planning through augmented reality (AR) and uses virtual reality (VR) for visualization through Synchronized Hybrid Petri Net (SHPN) simulation. Timed Petri Nets (TPNs) are used to control the processes within the MPS's workstations. Continuous Petri Nets (CPNs) handle the movement of the MCPRS. Task planning in AR enables users to interact with the system in real time using AR technology to visualize and plan tasks. SHPN in VR is a combination of TPNs and CPNs used in the virtual representation of the system to synchronize tasks between the MPS and MCPRS. The workpiece (WP) visits stations successively as it is moved along the line for processing. If the processed WP does not pass the quality test, it is taken from the last WS and is transported, by MCPRS, to the first WS where it will be considered for reprocessing or scrapping.

Programmable logic controllers (PLCs) are widely used in industry. Thus PLCs usually use the IEC 1131-3 standard programming language. The ladder diagram is the most popular language which does not require a lot of the steps and sequences of the operation. Therefore it is difficult to understand the program structure and developing the system. The Petri net is a graphical model that can explain the system operation easily and clearly. This paper presents the transformation structures from Petri nets to ladder diagram and possible implementation to control the process through the PLC's input and output.

Industrial control systems (ICS) are required to be operated safely under cyberattacks. Fallback control is necessary for the safe operation of ICS. As one of fallback control systems, we develop a resilient third-party monitoring system. This system consists of Programmable Logic Controllers (PLCs) for normal control and for fallback control. The normal PLC controls field devices, and the fallback PLC takes over the control after the normal PLC is attacked. The fallback control of this paper is the control takeover of a robot arm control system. To quickly transition to this fallback control, it is necessary to incorporate a supervisor function to manage each PLC function in an integrated manner. This paper aims to propose a modeling method of ICS functions and its analysis method to ensure that the supervisor can work properly under cyberattacks. For modeling, we use UPPAAL, specializing in formal verification by timed automata. We implement the models of each PLC and supervisor on UPPAAL. To quantitatively analyze whether the supervisor can really realize the incident response during cyberattacks, we give the specifications necessary for fallback control to the supervisor model using Timed Computation Tree Logic (TCTL) and verify its feasibility.

Given the growing computational power of embedded controllers, the use of model predictive control (MPC) strategies on this type of devices becomes more and more attractive. This paper investigates the use of online MPC, in which at each step, an optimization problem is solved, on both a programmable automation controller (PAC) and a programmable logic controller (PLC). Three different optimization routines to solve the quadratic program were investigated with respect to their applicability on these devices. To this end, an air heating setup was built and selected as a small‐scale multi‐input single‐output system. It turns out that the code generator (CVXGEN) is not suited for the PLC as the required programming language is not available and the programming concept with preallocated memory consumes too much memory. The Hildreth and qpOASES algorithms successfully controlled the setup running on the PLC hardware. Both algorithms perform similarly, although it takes more time to calculate a solution for qpOASES. However, if the problem size increases, it is expected that the high number of required iterations when the constraints are hit will cause the Hildreth algorithm to exceed the necessary time to present a solution. For this small heating problem under test, the Hildreth algorithm is selected as most useful on a PLC.

With the improvement of people's living standards, smart home is becoming more and more popular. Smart home is based on the residential, integrated a variety of modern advanced technologies such as wiring technology, centralized processing technology, network communication and other technologies will achieve integrated processing of various facilities in life. In contemporary society, people have higher and higher requirements for the quality of life, and the use of Programmable logic controller (PLC) to control smart homes has become popular. This paper draws on the traditional use of PLC to control the temperature and humidity of the greenhouse and the concentration of carbon dioxide, and considers the use of PLC to realize the control of smart home. The design uses PLC programmable controller to control the temperature and humidity of smart home life, making life more intelligent.

최근 자동 생산 시스템은 PLC (Programmable Logic Controller) 제어 프로그램을 일반적으로 사용하고 있다. 생산제품의 수명 주기가 길지 않기 때문에 공법과 라인 및 설비 변경이 자주 일어난다. 대부분, 기존 공정을 바탕으로 이루어지고 설비의 위치 및 제어정보를 수정한다. PLC 제어 프로그램 또한 기존 공정을 바탕으로 수정이 이루어진다. 새로운 제어 프로그램을 검증하기 위해서는 실제 생산 시스템을 구축하기 전에 가상의 공간에서 실제 공정과 같이 구성하여 순차적으로 공정이 진행되는 지 확인할 수 있는 방법이 필요하다. 본 연구는 순차제어(sequential control)와 병목현상 처리에 유용한 Timed-FSA를 기반으로 하는 논리적인 모델링 방법을 사용한다. 기존에 연구되었던 I-O 모델링과 I-O 모델링에서 요구되었던 하나의 설비에 다양한 상태의 정의를 통해 사용자의 시간과 공수를 절감하기 위한 기존 모델링에 페트리네트의 토큰(Petri Nets Coloured Token) 개념을 추가한 확장된 I-O 모델링 방법을 제안한다. 예제 설비를 통하여 사용자의 모델링 시간을 절감하는 실험과 사용자 평가를 통해 제안하는 확장된 I-O 모델링의 편의성을 검증한다. Recently manufacturing companies have used PLC control programs popularly for their automated production systems. Since the life cycle of production process is not so long, the change of the production lines occur frequently. Most of changes happen with modification of the position information and control process of the equipment. PLC control program is also modified based on the fundamental process. Therefore, to verify new PLC program by configuring virtual space according to real environment is needed. In this paper we show a logical modeling method, based on Timed-FSA useful for sequence control and dead-lock prevention. There is a problem wasting user's labor and time when defining a variety of states in a device. To overcome this problem, we propose an extended I-O model based on existing methods by adding a token concept of Petri Nets. Also we will show the usability of the extended I-O modeling through user study.

A new Petri-net-based design technique, called the inhibitor arc method, for the synthesis of compiled supervisors for discrete event systems is used to solve a forbidden state problem in an experimental manufacturing system. The technique used offers the following advantages: 1. The closed-loop (i.e. controlled) behaviours of the systems are non-blocking and do not contradict the forbidden state specifications. 2. The closed-loop behaviours of the systems are maximally permissive within the specifications. The supervisors to be synthesised consist of a controlled automation Petri net (APN) model of the system. Automation Petri nets include the following extensions to the ordinary Petri-net framework: sensor readings as firing conditions at transitions and actions assigned to places. Ladder logic diagram (LLD) code is used to implement the supervisors on programmable logic controllers (PLC). It is important to note that the supervisors obtained are correct by construction, therefore there is no need for verification. This paper particularly shows the applicability of previous results [1] to low-level real-time control where the role of the supervisor is to arrange low-level interaction between the control devices, such as motors, actuators, etc. This is done by considering an experimental manufacturing system.

A model based on a Petri net (PN) is proposed for controlling flexible manufacturing systems (FMSs). The model can describe not only normal sequential processes but also interruptive exceptional handling processes by means of simple structures. A layered structure and two types of token are introduced into a PN to describe exception handling and error recovery. An application in which this model was used to program a programmable logic controller (PLC) is described. The description of cell control can be simplified by the model. >