• Journal of KIISE:Software and Applications
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• v.37 no.1
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• pp.54-59
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• 2010

Special-purpose microcontrollers PLCs have been widely used in the area of industrial automation. For the research of analysis and verification for PLC programs, first of all we have to specify formal sematics of PLC programming languages. This paper defines formally the operational semantics of LD language. After we transform the graphical language LD into its textual representation Symbolic LD, we give semantics of Symbolic LD since LD language is a graphical language. This paper defines the natural sematics of Symbolic LD and formalizes it in Coq proof assistant.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.1
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• pp.33-38
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• 1999

This paper proposes a translation approach for PLCs (Programmable logic controllers) converting ladder diagrams directly to native codes, and describes detailed steps of the method followed by performance evaluation. A general-purpose DSP (Digital signal processor) based implementation validates the approach as well. A benchmark test shows that the Proposed translation framework fairly speeds up execution in comparison with the existing interpretation approach.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.17 no.30
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• pp.153-160
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• 1994

In this paper, we present the application of knowledge-based system technique for generating of PLC ladder diagram The developed prototype system receives a time chart as an input and generates a ladder logic as its output This results in the computerization and intellegent processing of PLC programming. The system can be effectively applied to sequence control where the PLC programs need to be frequently changed and generated.

• Journal of Institute of Control, Robotics and Systems
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• v.7 no.11
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• pp.939-943
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• 2001

PLC(programmable Logic Controller)s essential components of modern automation systems encompassing almost every industry. Ladder Diagrams (LD) have been widely used in the design of such PLC since the LD is suitable for the modeling of the sequential control system. However, the synthesis of LD itself mainly depends on the experience of the industrial engineer, which may results in unstructured or inflexible design. Hence, in this paper, we propose a ladder diagram conversion algorithm which systematically produces LDs for PLCs based on discrete event models to enhance the structured and flexible design mechanism.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.8
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• pp.706-712
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• 2002

In general, a deadlock in flexible manufacturing systems (FMSs) is caused by a resource limitation and the diversity of routings. However, the deadlock of industrial controllers such as programmable logic controllers (PLCs) can occur from different causes compared with those in general FMSs. The deadlock of PLCs is usually caused by an error signal between PLCs and manufacturing systems. In this paper, we propose a deadlock detection and recovery (DDR) algorithm to resolve the deadlock problem of PLCs at design stage. This paper employs the MAPN (modified automation Petri net), MTPL (modified token passing logic), and ECC (efficient code conversion) algorithm to model manufacturing systems and to convert a Petri net model into a desired LD (ladder diagram). Finally, an example of manufacturing systems is provided to illustrate the proposed DDR algorithm.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.5
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• pp.401-406
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• 2002

As product lifecycles become shorter, factories are pushed to develop small batches of many different products. The highly flexible control systems has become a necessity. The majority of existing automated industrial systems are controlled by programmable logic controllers(PLCs). In most cases, the control programs for PLCs are developed based on ladder diagrams(LDs). However, it is difficult to debug and maintain those LDs because the synthesis of LD itself mainly depends on the experience of the industrial engineer via trial-and-error methods. Hence, in this paper, we propose a discrete event model conversion algorithm for systematic analysis of LDs. The proposed discrete event model conversion algorithm is illustrated by an example of a conveyor system.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.7-10
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• 2002

The diagnosis of faults of machine tool, which is controlled by CNC and PLC, is generally based on ladder diagram of PLC. Because sequential controls for CNC and servo motor are mostly processed in PLC. However, when fault is occurred, a searching for logical relation to fault reasons is required a lot of fault experiences and times, because PLC program has step structure. In this paper, FDS(Fault Diagnosis System) is developed and implemented to machine tool with open architecture controller in order to find the reason of fault lastly and correctly. The diagnosed reasons for fault are tele-serviced on web through developed RSS(Remote Service System). The operationability and usefulness of developed system are evaluated on specially manufactured machine tool with open architecture CNC. The results of this research can be the model of remote monitoring and fault diagnosis system of machine tool with open architecture CNC.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.10
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• pp.89-97
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• 2003

The faults diagnosis of machine tool, which is controlled by CNC(Computer Numerical Control) and PLC(Programmable Logic Controller), is generally based on ladder diagram of PLC because sequential controls for CNC and servo motor are mostly processed in PLC. However, when fault is occurred, a searching of logical relationship for fault reasons is required a lot of diagnosis experiences and times because PLC program has step structure. In this paper, FDS(Fault Diagnosis System) is developed and implemented to machine tool with open architecture controller in order to find the reason of fault fast and correctly. The diagnosed reasons for fault are remote serviced on web through developed RSS(Remote Service System). The operationability and usefulness of developed system are evaluated on specially manufactured machine tool with open architecture CNC. The results of this research can be the model of remote monitoring and fault diagnosis system of machine tool with open architecture CNC.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2001.04a
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• pp.171-176
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• 2001

This paper describes the methodology of an IEC 1131-3-based control logic generator for the control system design and converting algorithm between programmable languages. The proposed control logic generator is generated based on the software model and common element with data type, variables, POUs(program organization unit) and execution control unit commonly used within programmable languages of IEC 1131-3 Standard. The generation method of object file was proposed on five programmable language based on IECI 131-3. The generation method of object file is represented as following; 1) the generation method using conversion algorithm from LD to IL with FBD(function block diagram), 2) the generation method using C code generation algorithm from SFC using the SFC execution sequence with FBD and ST(structured text). The proposed control logic generator was implemented by Visual C++ and MFC on MS-windows NT 4.0