This example is from the tutorial: A Petri-net for Hagen.

Author: Till Tantau Source: The PGF/TikZ manual


nodetutorial

Edit and compile if you like:

% Author: Till Tantau
% Source: The PGF/TikZ manual
\documentclass{article}
\def\xcolorversion{2.00}
\def\xkeyvalversion{1.8}
\usepackage[version=0.96]{pgf}
\usepackage{tikz}
\usetikzlibrary{arrows,snakes,backgrounds,petri}
\usepackage[latin1]{inputenc}
\begin{document}
\begin{tikzpicture}[node distance=1.3cm,>=stealth',bend angle=45,auto]
\tikzstyle{place}=[circle,thick,draw=blue!75,fill=blue!20,minimum size=6mm]
\tikzstyle{red place}=[place,draw=red!75,fill=red!20]
\tikzstyle{transition}=[rectangle,thick,draw=black!75,
fill=black!20,minimum size=4mm]
\tikzstyle{every label}=[red]
\begin{scope}
% First net
\node [place,tokens=1] (w1) {};
\node [place] (c1) [below of=w1] {};
\node [place] (s) [below of=c1,label=above:$s\le 3$] {};
\node [place] (c2) [below of=s] {};
\node [place,tokens=1] (w2) [below of=c2] {};
\node [transition] (e1) [left of=c1] {}
edge [pre,bend left] (w1)
edge [post,bend right] (s)
edge [post] (c1);
\node [transition] (e2) [left of=c2] {}
edge [pre,bend right] (w2)
edge [post,bend left] (s)
edge [post] (c2);
 
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Click to download: nodetutorial.texnodetutorial.pdf
Open in Overleaf: nodetutorial.tex