FUNCTION_BLOCK "FB_Cylinder_Adv"
{ S7_Optimized_Access := 'TRUE' }
VERSION : 0.2
   VAR_INPUT 
      i_xCmdFwd : Bool;       // Output Command Forward
      i_xCmdBcw : Bool;       // Output Command Backward
      i_xFwdSensor : Bool;    // DI: Physical Forward
      i_xBcwSensor : Bool;    // DI: Physical Backward
      i_xSimMode : Bool;      // TRUE = Ignore sensors, use internal simulation
      i_iSensorConfig : Int;  // 0:None, 1:Fwd Only, 2:Bcw Only, 3:Both
      i_tMoveTime : Time := T#1s;   // Expected travel time
      i_tTimeout : Time := T#2s;    // Alarm threshold
      i_xReset : Bool;
   END_VAR

   VAR_OUTPUT 
      q_xFwdOut : Bool;
      q_xBcwOut : Bool;
      q_xAtFwd : Bool;
      q_xAtBcw : Bool;
      q_xError : Bool;        // Timeout Alarm
   END_VAR

   VAR 
      s_tonFwd {InstructionName := 'TON_TIME'; LibVersion := '1.0'} : TON_TIME;
      s_tonBcw {InstructionName := 'TON_TIME'; LibVersion := '1.0'} : TON_TIME;
      s_tonWatchdog {InstructionName := 'TON_TIME'; LibVersion := '1.0'} : TON_TIME;
   END_VAR

BEGIN
    // 1. Directional Interlock
    q_xFwdOut := i_xCmdFwd AND NOT i_xCmdBcw;
    q_xBcwOut := i_xCmdBcw AND NOT i_xCmdFwd;

    // 2. Simulation vs. Real Logic
    s_tonFwd(IN := q_xFwdOut, PT := i_tMoveTime);
    s_tonBcw(IN := q_xBcwOut, PT := i_tMoveTime);

    IF i_xSimMode THEN
        // In simulation, we only care about the internal timers
        q_xAtFwd := s_tonFwd.Q;
        q_xAtBcw := s_tonBcw.Q;
    ELSE
        // Real World Logic based on Config
        CASE i_iSensorConfig OF
            0: // No Sensors
                q_xAtFwd := s_tonFwd.Q;
                q_xAtBcw := s_tonBcw.Q;
            1: // Fwd Only
                q_xAtFwd := i_xFwdSensor;
                q_xAtBcw := s_tonBcw.Q;
            2: // Bcw Only
                q_xAtFwd := s_tonFwd.Q;
                q_xAtBcw := i_xBcwSensor;
            3: // Both Sensors
                q_xAtFwd := i_xFwdSensor;
                q_xAtBcw := i_xBcwSensor;
        END_CASE;
    END_IF;

    // 3. Watchdog Alarm (Trip if moving but not arriving)
    s_tonWatchdog(IN := (q_xFwdOut AND NOT q_xAtFwd) OR (q_xBcwOut AND NOT q_xAtBcw), 
                  PT := i_tTimeout);
    
    IF s_tonWatchdog.Q THEN q_xError := TRUE; END_IF;
    IF i_xReset THEN q_xError := FALSE; END_IF;

END_FUNCTION_BLOCK