Modelling and Verification of PLC-Based Systems Programmed with Ladder Diagrams

On Controller and Plant Modeling for Model-based Formal Verification

“…We omit its details out of this paper. Here are given main definitions: TNCES ={P,T,F,mo,yv,CN,EN,DC}(1) [1] {Cin ,Ein,Cout,Eot, Bc, Be, Cs, Dt} (2) [1] DC = {DR,DL,D0} (3) [1] TNCES,omposite = {M, CminP, Cm0Ut,Eninp,Emn0,Ic, Je} (4) [5] Figure 1 demonstrates the approach:. Tp is the function that translates UML diagrams to the TNCES [7].…”

“…During modeling phase we tend to represent any phenomenon state/parameter of the system by means of Boolean variables. The representation of Boolean modules in TNCES can be found in [5], [6], [8].…”

“…Figure 3 shows an initial controller model TNCEScomposite (4), which includes two TNCES modules (1): change_check and Skeleton. The change check module has been described in [5]. Its function is to monitor if any change occur somewhere in the Net.…”

“…All the model elements, which should report the change in the state (transition of the token), has to be connected to the change event input of change_check module or to the change_in Plant event input of controller model in the case of external components for the controller model. VOLUME R={C,I,9} (5) where C={c1, C2, ..., Cklis a finite set of Boolean conditions formed by LD contacts, I=Ji{, i2, ..., im is a finite set of instructions and coils in the rack and : ii o-ci is a function that maps instruction ij of I to condition ci of C.…”

“…The trivial example that requires plant model was demonstrated in [5]. A simple tank that filled with a liquid when input valve is open is one of the examples that requires plant model.…”