GRAFCET and Petri Nets Outline Introduction GRAFCET - EPFL
GRAFCET and Petri Nets Outline Introduction GRAFCET - EPFL
GRAFCET and Petri Nets Outline Introduction GRAFCET - EPFL
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Modelling with PNs<br />
Conditions « <strong>and</strong>" & « or"<br />
actions associated to places<br />
Activated by token presence<br />
actions associated to<br />
transitions (short duration)<br />
Activated by transition<br />
firing<br />
Task<br />
waiting<br />
Start of<br />
execution<br />
executing p 3<br />
End of<br />
execution<br />
Tasked<br />
ended<br />
p 1 p 2<br />
p 4<br />
Processor<br />
free<br />
type "AND" type "OR"<br />
p 1 p 2 p 3<br />
p 1 p 2 p 3<br />
x 1 x 2 x 3<br />
x 1 x 2 x 3<br />
y<br />
p 4<br />
t 1<br />
t 1<br />
p 4<br />
t<br />
t 3<br />
2<br />
y<br />
Real-Time Programming <strong>GRAFCET</strong> <strong>and</strong> <strong>Petri</strong> nets 81<br />
© J.-D. Decotignie, 2007<br />
Real-Time Programming <strong>GRAFCET</strong> <strong>and</strong> <strong>Petri</strong> nets 82<br />
© J.-D. Decotignie, 2007<br />
<strong>Introduction</strong> of external conditions<br />
When synchronisation is required<br />
controlled system →<br />
controlling system<br />
Label on the transition<br />
(if condition, action)<br />
Transition may be fired iif<br />
external condition satisfied<br />
Timers (extern or<br />
minimal sejourn duration in a place)<br />
Task<br />
waiting<br />
(.,begin_exec)<br />
executing<br />
p 3<br />
(end_exec,.)<br />
Task<br />
terminated<br />
p 1 p 2<br />
p 4<br />
Processor<br />
free<br />
<strong>Introduction</strong> of external conditions<br />
(2)<br />
Task<br />
waiting<br />
(.,begin_exec)<br />
executing<br />
p 3<br />
(end_exec,.)<br />
Task<br />
terminated<br />
p 1 p 2<br />
p 4<br />
Processor<br />
free<br />
p 13<br />
p 14<br />
t 11<br />
p 17<br />
(.,end_exec)<br />
p 11<br />
t 12 t 13<br />
(begin_exec, .)<br />
p 15<br />
t 14<br />
t 15<br />
p 16<br />
Real-Time Programming <strong>GRAFCET</strong> <strong>and</strong> <strong>Petri</strong> nets 83<br />
© J.-D. Decotignie, 2007<br />
Real-Time Programming <strong>GRAFCET</strong> <strong>and</strong> <strong>Petri</strong> nets 84<br />
© J.-D. Decotignie, 2007
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