Dariusz Rzonca

CPDev Engineering Environment for Modeling, Implementation, Testing, and Visualization of Control Software

The paper presents the CPDev engineering environment, which is a comprehensive set of integrated tools for programming PLCs, PACs, and DCSs, according to the IEC 61131-3 standard. The environment supports various parts of the project development, including modeling (using SysML diagrams), implementation (with IEC 61131-3 textual, graphical, and mixed languages), testing (by textual, table, and performance tests), simulation (in off-line mode), debugging (with tracing variable values and breakpoints), hardware resources configuration, execution (either on the virtual machine or FPGA-based hardware machine), as well as visualization. The CPDev project is designed in a way supporting portability. Therefore, prepared control programs can be run on any supported target platform, such as AVR, ARM, and x86. The environment has a few applications, both industrial and laboratory.

Testing communication tasks in distributed control systems with SysML and Timed Colored Petri Nets model

HighlightsThere is a lack of appropriate methodologies and tools applicable to small- and medium-sized DCSs, especially for analysis and testing of communication tasks during early development stages. The paper proposes a flexible and efficient approach that fills this gap.Communication tasks and their parameters are specified in the SysML modeling language.The diagrams are used to automatically generate a model of communication subsystem in the Timed Coloured Petri Nets (TCPNs) formalism.Simulation of the TCPN model allows to estimate performance of a target system implementation and to predict its behavior in various cases. Nowadays, Distributed Control Systems (DCSs) are commonly used and supersede stand-alone controllers in many industrial applications. Efficient communication is crucial for their proper operation. Unfortunately, there is a lack of appropriate methodologies and tools applicable to small- and medium-sized DCSs, especially for analysis and testing of communication tasks during early development stages. The paper proposes a flexible and efficient approach that fills this gap. It consists of the following steps. At the beginning, communication tasks and their parameters are specified using graphical diagrams from Systems Modeling Language (SysML). Then, the diagrams are used to automatically generate a model of communication subsystem in the Timed Colored Petri Nets (TCPNs) formalism. Finally, simulation of the TCPN model allows to estimate performance of a target system implementation and to predict its behavior in various cases. Thus, potential bottlenecks might be identified earlier and easier, as well as eliminated even before creation of a hardware prototype. The proposed approach has been introduced into the Control Program Developer (CPDev) engineering environment, which allows to program industrial controllers. Appropriate software tools, namely the editor for SysML communication model, the TCPN library with simulation engine, and the testing framework have been prepared.

Communication Performance Tests in Distributed Control Systems

The paper presents a concept and implementation of Communication Performance Tests (CPT) for small distributed control systems. Requirements for the communication performance are specified using SysML notation. Test cases included in the specification are translated into a dedicated test definition language CPTest+. System implementation is then verified by executing the tests generated from the specification and analyzing results of test runs. The procedure is supported by specialized tools integrated with IEC 61131-3 development environment, including SysML model editor and CPTest testing environment.

Data Acquisition Server for Mini Distributed Control System

The paper describes PACQ, a distributed control mini system. WWW and data acquisition functionality of PACQ server is presented from the user perspective together with a discussion on security issues. The communication between the server and control modules is modelled with hierarchical timed coloured Petri net. Programmability of the control modules using CPDev environment and their system software is also characterized.

Measuring, Monitoring, and Analysis of Communication Transactions Performance in Distributed Control System

Nowadays, distributed control systems often consist of complex software executed on many components connected together. Due to performing crucial tasks in industry, it is important to ensure that communication between devices in distributed control systems works as expected and does not reach nor is dangerously close to the given boundary value. The paper presents a concept of Extended Communication Performance Tests, together with their development and execution. What is more, a way of measuring, monitoring, and analysis of communication in a small distributed control system is proposed. A structure of system, communication tasks, and performance requirements are modeled on three kinds of SysML diagrams, namely Block Definition, Internal Block, and Requirement Diagram. Test cases are automatically generated in the CPTest+ test definition language. A set of dedicated tools allows engineers to monitor communication time parameters in the on-line mode, check constraints, and prepare performance analysis. The concept has been integrated with the CPDev engineering environment designed for programming industrial controllers, as well as small and medium-sized distributed control systems.

Hierarchical Petri Net for the CPDev Virtual Machine with Communications

Hierarchical Coloured Petri nets are used to model interaction of CPDev virtual machine with communication subsystem of a small distributed control and measurement system. The machine executes control programs and implements communications. Both vertical and horizontal communication are modelled, as shown by the example of the distributed system with new SMC programmable controller. The model can be used to analyse correlation between the machine cycle time and communication load and to determine optimal parameters of the system.

Analysis of Challenge-Response Authentication in a Networked Control System

Analysis of authentication time in challenge-response protocol has been presented here. The protocol has been used in a prototype Networked Control System (NCS) with multiple Plant Control Units (PCU) and Supervisory Control Unit (SCU). The units are programmed in IEC 61131-3 compliant CPDev (Control Program Developer) environment. Global variable manager is used to share common data across the network. The paper presents theoretical estimation of the handshake time during authentication between SCU and PCU. Experiments have been carried out to compare the estimations with a real application.

Event-Driven Approach to Modeling and Performance Estimation of a Distributed Control System

Currently Distributed Control Systems are commonly used in the industry. Proper operation of such systems depends on reliable and efficient communication. Simulation of the system operation in different conditions, performed during early development stages, allows to estimate performance and predict behavior of final implementation. In this paper new event-driven model of a DCS has been introduced and compared with the previous one. Structure of the model decreased simulation time and improved scalability of the approach, whereas precision of the results was not diminished.

CPDev engineering environment for control programming

Programming a control example by CPDev tool using LD, FBD, and SFC graphical languages of IEC 61131-3 standard is presented. Another example demonstrates the use of data structures and arrays of function blocks in ST textual language. The two parts indicate that CPDev provides now essential functionalities specified in the standard. Remarks how the tool relates to established engineering environments such as CoDeSys, STEP 7, Control Builder F, and ISaGRAF are also given.

Small prototype acquisition system with secure remote data access

The paper describes Small Data Acquisition System, named PACQ, which can be used for collecting data from user-programmable I/O modules and sharing data through a web browser. All connections and data transfers between the client and the server are secure. Due to the resource restrictions only symmetric cryptography and challenge-response protocol could be used, but the solution should be resistant to most of common attacks.