scholarly journals Algorithm to Convert Signal Interpreted Petri Net Models to Programmable Logic Controller Ladder Logic Diagram Models

Author(s):  
Z. Aspar ◽  
Nasir Shaikh-Husin ◽  
M. Khalil-Hani

<span>Signal Interpreted Petri Nets (SIPN) modeling has been proposed as an alternative to Ladder Logic Diagram (LLD) modeling for programming complex programmable logic controllers (PLCs) due to its high level of abstraction and functionalities. This paper proposes an algorithm to efficiently convert existing SIPN models to their LLD models equivalences. In order to automate and speed up the conversion process, matrix calculation approach is used. A complex SIPN model was used to show that existing conversion technique must be expanded in order to cater for a more complex SIPN models.</span>

Author(s):  
Dmitry A. Zaitsev

Functional Petri nets and subnets are introduced and studied for the purpose of speed-up of Petri nets analysis with algebraic methods. The authors show that any functional subnet may be generated by a composition of minimal functional subnets. They propose two ways to decompose a Petri net: via logical equations solution and with an ad-hoc algorithm, whose complexity is polynomial. Then properties of functional subnets are studied. The authors show that linear invariants of a Petri net may be computed from invariants of its functional subnets; similar results also hold for the fundamental equation of Petri nets. A technique for Petri nets analysis using composition of functional subnets is also introduced and studied. The authors show that composition-based calculation of invariants and solutions of fundamental equation provides a significant speed-up of computations. For an additional speed-up, they propose a sequential composition of functional subnets. Sequential composition is formalised in the terms of graph theory and was named the optimal collapse of a weighted graph. At last, the authors apply the introduced technique to the analysis of Petri net models of such well-known networking protocols as ECMA, TCP, BGP.


2020 ◽  
Vol 1 (2) ◽  
pp. 21-29
Author(s):  
Nyan Phyo Aung ◽  
Mo Mo Myint Wai ◽  
Lwin Lwin Htay

Advance of a road traffic light control system using Programmable Logic Controller is the principal of the system. This system can be divided into two parts which are hardware and software. The hardware part for this system is a model of four -way junction of a traffic light. The Red, Yellow and Green are installed at each lane to represent as a traffic light signal indicator. This switches and lamps are linked to PLC. The PLC receives signal which is coming from the inputs (sensor and switch) and drives the units (lamps or relays). In the system, Siemens s7-200 PLC is used as the main controller of the traffic light system. The Step7 Micro Win software can be developed the ladder logic diagram which can control the traffic light for proposed system. So, the traffic light system can be successfully controlled by PLC.


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