text: <user>
  Create a function block for a safety interlock system in TwinCAT Structured Text<|endoftext|>
  <assistant>
  FUNCTION_BLOCK FB_SafetyInterlock
  VAR_INPUT
      bEmergencyStop : BOOL;    // Emergency stop button input
      bGuardDoorClosed : BOOL;  // Guard door closed sensor input
      bResetButton : BOOL;      // Reset button input
  END_VAR
  
  VAR_OUTPUT
      bMachineEnabled : BOOL;   // Machine enable output
      nErrorCode : UINT;        // Error code output
  END_VAR
  
  VAR
      fbTON_Reset : TON;        // Timer for reset button debounce
      bInternalState : BOOL;    // Internal state of the interlock system
  END_VAR
  
  // Main program logic
  IF bEmergencyStop AND bGuardDoorClosed AND NOT bInternalState THEN
      // Start reset timer when conditions are met and system is not enabled
      fbTON_Reset(IN := bResetButton, PT := T#500MS);
      
      IF fbTON_Reset.Q THEN
          // Enable the machine after reset button is pressed for 500ms
          bInternalState := TRUE;
          nErrorCode := 0;
      END_IF
  ELSIF NOT bEmergencyStop THEN
      // Emergency stop activated
      bInternalState := FALSE;
      nErrorCode := 16#0001;
  ELSIF NOT bGuardDoorClosed THEN
      // Guard door opened
      bInternalState := FALSE;
      nErrorCode := 16#0002;
  END_IF
  
  // Set machine enable output
  bMachineEnabled := bInternalState;
  
  // Error handling and safety measures
  IF nErrorCode <> 0 THEN
      // Log error to system logger (implementation depends on specific TwinCAT setup)
      // Example: LogError(nErrorCode);
  END_IF
  
  (*
  Explanation of the implemented PLC software concept:
  This function block implements a basic safety interlock system for a machine. 
  It monitors an emergency stop button and a guard door sensor. The machine 
  can only be enabled when both the emergency stop is not activated and the 
  guard door is closed. A reset button with a 500ms debounce timer is required 
  to enable the machine after safety conditions are met.
  
  Suggested TwinCAT 3 features or programming techniques to enhance the implementation:
  1. Use of TwinCAT 3 Safety PLC for critical safety functions.
  2. Implementation of a state machine using enumerated types for more complex behavior.
  3. Integration with TwinCAT HMI for visual representation of the safety system status.
  *)<|endoftext|>
  