(* Traffic light junction. *)
(* Run the junction: north-south green, then amber, then red while east-west goes green, amber, red, and round again. Never show two greens, always show amber between green and red, never leave a head dark, and give each direction at least four seconds of green. *)

VAR_GLOBAL
  NS_Red   AT %QX0.0  : BOOL; (* North-south red lamp *)
  NS_Amber AT %QX0.1  : BOOL; (* North-south amber lamp *)
  NS_Green AT %QX0.2  : BOOL; (* North-south green lamp *)
  EW_Red   AT %QX0.3  : BOOL; (* East-west red lamp *)
  EW_Amber AT %QX0.4  : BOOL; (* East-west amber lamp *)
  EW_Green AT %QX0.5  : BOOL; (* East-west green lamp *)
END_VAR

PROGRAM Main
  (* Write the logic here. *)
END_PROGRAM