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Petri Net Examples

GRAFCET Action Qualifiers

In GRAFCET mode, each step can have actions with different qualifiers that define their behavior according to IEC 60848:

Qualifier Name Description
N Normal Action is active while the step is active
S Set (Stored) Action is latched ON when step becomes active, remains ON until Reset
R Reset Action is latched OFF when step becomes active
D Delayed Action becomes active after delay, only while step remains active
L Limited Action is active for limited duration while step is active
SD Stored & Delayed Action is set after delay (combination of S and D)
DS Delayed & Stored Action starts delayed, then stored (combination of D and S)
SL Stored & Limited Action is set for limited time (combination of S and L)
P Pulse Single pulse at step activation (impulse action)

GRAFCET with Actions (Cylinder Control)

This example demonstrates a pneumatic cylinder control sequence with various action qualifiers:

  • Init: Initial waiting state
  • Extending: Activates valve V1+ (Normal action)
  • Extended: Starts a 2s timer (Delayed) and sets position indicator (Set)
  • Retracting: Activates valve V1- (Normal) and resets indicator (Reset)
  • Alarm: Sound buzzer (Normal) and flash lamp for 5s (Limited)

Sensors: Start, s0 (retracted position), s1 (extended position), Error, Reset

TimedPetriNetEditor data/examples/GrafcetActions.json

Graphe des Modes de Marche et Arret (GEMMA)

Operating and Stopping Modes Graph (GEMMA)

This example models the GEMMA (Graph for the Study of Modes and Actions) which defines the coordination of three combined GRAFCETs to control an automated cell. The managed modes are:

  • Normal production operation
  • Safety operation
  • Supervision/control of subordinate GRAFCETs

Production Line Description: Workpieces are transported by a conveyor belt to an oven (KM3) for baking. The conveyor can move left or right thanks to two motors (KM2 and KM1).

Operator Panel (HMI) Controls:

  • Emergency stop button (AU)
  • Reset button (Arm)
  • Validation button (Val)
  • Power-on indicator lamp (MST)
  • Selector switch for automatic (Auto) or manual (Manu) operation
  • Cycle start button (Dcy)
  • Cycle stop button (Acy)
  • Left (GA) and right (DR) buttons to move the conveyor in the desired direction during manual mode

Credit: NetProf

TimedPetriNetEditor data/examples/GEMMA.json

Coffee machine

The client inserts a coin and press to the brew button to get a coffee. The machine accept to return the inserted client coin.

Coffee

TimedPetriNetEditor data/examples/Coffee.json

Traffic Lights

Two traffic lights (red, orange, red lights) synchronized by the Place P6.

Traffic Lights

TimedPetriNetEditor data/examples/TrafficLights.json

German Traffic Lights

One traffic ligth. The particularity of German traffic lights is they are at the same time red and yellow before swaitching to green.

TimedPetriNetEditor data/examples/GermanTrafficLights.json

Credit: YAWL User Group https://www.youtube.com/shorts/ZQZCpDRqwKY

Philosphers

Three philosophers are eating but they are sharing their fork and knives.

Philosophers

TimedPetriNetEditor data/examples/Philosophers.json

Urgency Call (French 911)

Victims is calling the 911. A first operator (level 1) is selecting the type of urgency (advice urgent, critical):

  • For an advice the operator is giving instructions to the victim.
  • For a urgent case, the phone call is transfered to the operator of level 2.
  • For a critical case, the phone call is transfered to the operator of level 2 but the operator of level 1 is still present with the victim.

Appels Durgence

TimedPetriNetEditor data/examples/AppelsDurgence.json

Four Roads Junction

Simulate a road junction.

Four Road Junctions

TimedPetriNetEditor data/examples/FourRoadJunctions.json

Producer Consumer

Simulate a producer and a consumer with a buffer.

Producer Consumer

TimedPetriNetEditor data/examples/ProducerConsumer.json

Inputs Outputs

Show source and sinks transitions

Inputs Outputs

TimedPetriNetEditor data/examples/InputsOutputs.json

Event Graph

Show a timed event graph taken from https://www.rocq.inria.fr/metalau/cohen/SED/book-online.html.

Event Graph

TimedPetriNetEditor data/examples/EventGraph.json

Chainsaw Safety

Show security such as dead man works on a chainsaw.

TimedPetriNetEditor data/examples/Chainsaw.json

Credit: YAWL User Group https://www.youtube.com/shorts/V42WiF2Ib3w

Landing Gear

Show how to prevent damaging aircraft landing gear.

  • The aircraft has initially its gear down and at low speed.
  • On high speed, extending gears is not possible.
  • If gears are down and aircraft go to high speed a warning is triggered.
TimedPetriNetEditor data/examples/LandingGear.json

Credit: YAWL User Group https://www.youtube.com/shorts/IqMyF5JKoE4

Smarthome Safety

Prevent shuttering down the last roller shutters.

TimedPetriNetEditor data/examples/SmarthomeSafety.json

Credit: YAWL User Group https://www.youtube.com/shorts/BB5N9Nxtq00