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Publications

Publications by Mário Rodrigues Sousa

2010

Analyzing the Compatibility Between ISA 88 and IEC 61499

Authors
de Sousa, M;

Publication
2010 IEEE CONFERENCE ON EMERGING TECHNOLOGIES AND FACTORY AUTOMATION (ETFA)

Abstract
In the last years many standards have been created for the industrial control domain. Some have found wide adoption in the industiy, while others seem to never leave the stage of a promising technology. An example of the first type is ISA 88, that defines an architectural design for control applications for the batch process industiy. The author is of the opinion that IEC 61499 is an example of the latter. In this paper the author analyzes how the design architecture defined in ISA 88 may be implemented using the programming framework defined in IEC 61499. Even though ISA 88 and IEC 61499 both follow an event based and object-oriented approach, the author uncovers a fundamental constraint of the IEC 61499 related to the dynamic invocation of services from distinct object instances. Without tiying to extend the IEC 61499 standard, two approaches are presented to work around this constraint.

2010

Proposed corrections to the IEC 61131-3 standard

Authors
de Sousa, M;

Publication
COMPUTER STANDARDS & INTERFACES

Abstract
The IEC (International Electrotechnical Commission) 61131-3 standard defines several programming languages which may be used to develop industrial control applications. These applications typically execute on industrial PLCs (Programmable Logic Controller). PLC vendors have embraced the first version of this standard [3], with each vendor adopting it at its own pace. As the standard is implemented, several deficiencies have been uncovered. In this paper deficiencies identified by the authors during the implementation of a compiler, compliant with the second version of the standard 141, are explained and analysed. Other deficiencies identified by other authors have also been aggregated and explained. For each deficiency, one or more suggestions (including changes to the formal syntax definition) are made as to how the standard could be changed in order to rectify the deficiency.

2012

Data-Type Checking of IEC61131-3 ST and IL Applications

Authors
de Souza, M;

Publication
2012 IEEE 17TH CONFERENCE ON EMERGING TECHNOLOGIES & FACTORY AUTOMATION (ETFA)

Abstract
The IEC 61508 standard recognizes the programming languages defined in IEC 61131-3 as being appropriate for safety-related applications, and suggests the use of static data type analysis of the source code. In this context, we have added a data type semantic verifier to the MatIEC compiler - an open source ST, IL and SFC code translator to ANSI C. In so doing, we have identified several issues related to the definition of the semantics of the IL and ST programming languages, as well as with the data type model defined in IEC 61131-3. In this paper we describe the issues we uncovered, explain how the data type static analyzer of the MatIEC was implemented, explain the options we took, and suggest how the IEC 61131-3 standard could be made more explicit.

1997

Development of an ORB for distributed manufacturing applications

Authors
Carvalho, AS; deSousa, MJ;

Publication
WFCS '97 - 1997 IEEE INTERNATIONAL WORKSHOP ON FACTORY COMMUNICATION SYSTEMS, PROCEEDINGS

Abstract
The control of manufacturing processes requires the use of a communication infrastructure. Since the object-oriented model is well adapted for the modelling of industrial processes, an ORE seems the logical choice for the communication layer. This paper presents an ORE developed for this purpose, based on DCE services.

2007

Management of replicated IEC 61499 applications

Authors
De Sousa, M; Santos, AA;

Publication
IEEE International Conference on Industrial Informatics (INDIN)

Abstract
The IEC-61499 standard defines a framework in which distributed control applications may be developed, and how these are interpreted and executed. With the distributed nature of the control applications, many new issues also need to be taken into account. Most of these arise due to the new error model and failure modes of the distributed hardware on which the distributed application is being executed. On the other hand, the distributed nature of the hardware also allows new capabilities to be explored, such as improved reliability through masking of faults. Fault tolerance is usually achieved by the use of replication. Replication at the software level allows for much smaller granularity, but all replicas must be kept synchronised in order to produce the same output data and events. To achieve replica determinism all replicas must process the same set of inputs in the same order, and the outputs of the replicas must somehow be consolidated. The IEC 61499 framework however does not explicitly handle the replication of software components. In this paper we propose a replication model for IEC-61499 applications, and discuss which mechanisms and protocols may be used for their support. In short, replica determinism is achieved through the use of distributed synchronised clocks, atomic multicast protocols, as well as timed messages. ©2007 IEEE.

2012

Data-type checking of IEC61131-3 ST and IL applications

Authors
De Sousa, M;

Publication
IEEE International Conference on Emerging Technologies and Factory Automation, ETFA

Abstract
The IEC 61508 standard recognizes the programming languages defined in IEC 61131-3 as being appropriate for safety-related applications, and suggests the use of static data type analysis of the source code. In this context, we have added a data type semantic verifier to the MatlEC compiler - an open source ST, IL and SFC code translator to ANSI C. In so doing, we have identified several issues related to the definition of the semantics of the IL and ST programming languages, as well as with the data type model defined in IEC 61131-3. In this paper we describe the issues we uncovered, explain how the data type static analyzer of the MatlEC was implemented, explain the options we took, and suggest how the IEC 61131-3 standard could be made more explicit. © 2012 IEEE.

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