tmpa-2017: modeling of plc-programs by high-level coloured petri nets
TRANSCRIPT
Modeling of PLC programs with High-level ColouredPetri Nets
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A.
Yaroslavl State University
2017
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A. Modeling of PLC programs with High-level Coloured Petri Nets
Programmable Logic Controller (PLC) 2/12
INPUTS OUTPUTSPROGRAM
EXECUTION
PLC characteristics.Inputs: sensors, limit switches, buttons, meters . . . .Outputs: electromagnetic relays, motors, light indicators . . . .Working cycle: reading from inputs,
program execution,writing to outputs.
Wide sphere of application.
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A. Modeling of PLC programs with High-level Coloured Petri Nets
The approach to constructing programs 3/12
Proposed sequence of writing PLC-programs:
Creating LTL-specificationGX(¬_V ∧ V ⇒ FiringCond )
GX(_V ∧ ¬V ⇒ FiringCond ′)
Translation to SMV language and verificationcase{ ∼V & next(FiringCond ) : next(V ) := 1;
V & next(FiringCond ′) : next(V ) := 0;default : next(V ) :=V ; }.
Translation to IEC 61131-3 standard lanuagesIF NOT _V AND FiringCond THEN V := 1 ;ELSIF _V AND FiringCond ′ THEN V := 0; END_IF.
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A. Modeling of PLC programs with High-level Coloured Petri Nets
PLC-programming by LTL-specification 4/12
Conditions for program variables:
1 Each variable value must not change more than once per onepass of PLC working cycle.
2 The value of each variable must change at only one place inthe program.
GX( V>_V ⇒ OldValCond ∧ FiringCond ∧ V =NewValExpr )
GX( V<_V ⇒ OldValCond ′ ∧ FiringCond ′ ∧ V =NewValExpr ′ )GX(V=_V ⇒ ¬(OldValCond ∧ FiringCond)∧¬(OldValCond ′ ∧ FiringCond ′))
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A. Modeling of PLC programs with High-level Coloured Petri Nets
Restrictions of the approach 5/12
Typical PLC Tasks:
Hydraulic system
Library lift
Installation for preparation of mixtures
Installation for lime dosage
The approach is applicable for discrete tasks of logical control,requiring PLCs with binary inputs and outputs. SMV allows to buildmodels with 259 states.
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A. Modeling of PLC programs with High-level Coloured Petri Nets
Translation to Petri net 6/12
LTL-specification:
GX( V>_V ⇒ OldValCond ∧ FiringCond ∧ V =NewValExpr );GX( V<_V ⇒ OldValCond ′ ∧ FiringCond ′ ∧ V =NewValExpr ′ ).
Common scheme of a transition of Petri net:
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A. Modeling of PLC programs with High-level Coloured Petri Nets
Installation for preparation of mixtures 7/12
PVlv
LS0
LS1
LS2
Mtr
Tank 2
Tank 1
Vlv2
Vlv1
Tank 2 empty
Tank 1 empty
MS
EVlv
Emergency
valve
Pouring
valve
TS1
TS2
Level 2
Level 1
Level 0
Finished
Proper
Spoiled
Mixture
Component 2Component 1
Components in reservoir
Vlv1
Vlv2Working
On
Motor
Error
Motor
Valves
Vlv1
Vlv2
PVlvPVlv
EVlv
Control panelScheme of installation
Reservoir
Valves / lampsSwitches
PLC OutputsInputs
SBPVlv
Open pouring valve Open pouring valve
PVlv
Open valve 1
1 1
2
Vlv1SBVlv1
Open valve 1
2
SBVlv2
Open valve 2
3
SBMtr
Start motor
5
Sensors
LS0
Level sensor 0
8
LS1
Level sensor 1
9
LS2
Level sensor 2
10
Open valve 2
3
Vlv2
Start motor
5
Mtr
MS
Motor sensor
11
Open emergency valve
4
EVlvSBEVlv
Open emergency valve
4
TS1
6
TS2
Tank sensor 2
7
States / lamps
Mixture is proper
6
7
Mixture is spoiled
8
Component 2 in mixture
10
Component 1 in mixture
9
11
MxIsFin
MxIsPrp
MxIsBad
C1InMx
C2InMx
MtrErr
Mixture is finishedTank sensor 1
Motor error
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A. Modeling of PLC programs with High-level Coloured Petri Nets
Petri Net 8/12
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A. Modeling of PLC programs with High-level Coloured Petri Nets
Consistent behaviour of sensors 9/12
Additional fine-tuning program model for corresponding to theactual behaviour of the PLC programs
G( X( S)⇒ Cond1 ),G( X(¬S)⇒ Cond1 ′).
G( ¬S ∧ X( S)⇒ Cond2 ),G( S ∧ X(¬S)⇒ Cond2 ′ ).
These formulas are written in guard condition of Input transition.Some examples:
(not p_TS1 orelse TS1 orelse p_Vlv1),(not p_TS2 orelse TS2 orelse p_Vlv2),(not MS orelse p_Mtr),(LS0 orelse not LS1 andalso not LS2)
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A. Modeling of PLC programs with High-level Coloured Petri Nets
Examples of temporal properties 10/12
“Overspending”. Components will never be added to thespoiled mixture.
G(¬(MxIsBad ∧ (Vlv1 ∨ Vlv2)))
“Spoiled product”. The spoiled mixture will never be drainedthrough valve “PVlv”.
G(¬(MxIsBad ∧ PVlv))
“Spoiled mixture”. Spoiled mixture can not be proper orfinished.
G(¬(MxIsBad ∧ (MxIsPrp ∨MxIsFin)))
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A. Modeling of PLC programs with High-level Coloured Petri Nets
Conclusion 11/12
CPN Tools provides availabilities to:
show data flows from input variables to outputs
demonstrate dependences between inputs, outputs andprogram variables
visualize possible concurrent blocks
modeling resources and timing with tokens
make simulation modeling for checking some class of properties
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A. Modeling of PLC programs with High-level Coloured Petri Nets
Thank you!
Ryabukhin D. A., Kuzmin E. V., Sokolov V. A. Modeling of PLC programs with High-level Coloured Petri Nets