/* beer vat pressure release valve */
digraph {
  pad=0.5; bgcolor="lightgrey"; nodesep=1; ranksep=0.3;
  node [shape="box"; style="filled";  fillcolor="cyan";  ];
  edge [labelfontsize=10; minlen=2; labeldistance=2 ];
  CLOSED [label="CLOSED\npressure valve closed"];
  FLASHING [label="FLASHING\nstart blinking LED"]; 
  BEEPING [label="BEEPING\nturn on the alarm sound"]; 
  OPENING [label="OPENING\nslowly open the relief valve"]; 
  CLOSING [label="CLOSING\nslowly close the relief valve"]; 
  CLOSED -> FLASHING [taillabel="EVT_PRESSURE";]
  FLASHING -> BEEPING  [taillabel="EVT_TIMER";]
  BEEPING -> OPENING [taillabel="EVT_TIMER";]
  OPENING -> OPEN [taillabel="EVT_TIMER";]
  OPEN -> CLOSING [taillabel="EVT_TIMER";]
  CLOSING -> CLOSED [taillabel="EVT_TIMER";]
  CLOSED -> OPENING [taillabel="EVT_BUTTON";]
  FLASHING -> OPENING [taillabel="EVT_BUTTON";]
  BEEPING -> OPENING [taillabel="EVT_BUTTON";]
  OPEN -> CLOSING [taillabel="EVT_BUTTON";]
}