text: <user>
  Create a function block for temperature control in TwinCAT Structured Text<|endoftext|>
  <assistant>
  FUNCTION_BLOCK FB_TemperatureControl
  VAR_INPUT
      fSetpoint       : REAL;    // Desired temperature setpoint
      fCurrentTemp    : REAL;    // Current temperature reading
      bEnable         : BOOL;    // Enable control
  END_VAR
  VAR_OUTPUT
      fHeaterOutput   : REAL;    // Heater output (0-100%)
      bAlarm          : BOOL;    // Temperature alarm
  END_VAR
  VAR
      fError          : REAL;    // Temperature error
      fIntegral       : REAL;    // Integral term
      fKp             : REAL := 2.0;    // Proportional gain
      fKi             : REAL := 0.1;    // Integral gain
      fMaxOutput      : REAL := 100.0;  // Maximum output
      fMinOutput      : REAL := 0.0;    // Minimum output
      tTaskCycle      : TIME := T#10MS; // PLC task cycle time
      fHighAlarmLimit : REAL := 90.0;   // High temperature alarm limit
  END_VAR
  
  // Main control logic
  IF bEnable THEN
      // Calculate error
      fError := fSetpoint - fCurrentTemp;
      
      // Update integral term
      fIntegral := fIntegral + fError * (TIME_TO_REAL(tTaskCycle) / 1000.0);
      
      // Calculate PID output
      fHeaterOutput := (fKp * fError) + (fKi * fIntegral);
      
      // Limit output
      fHeaterOutput := LIMIT(fMinOutput, fHeaterOutput, fMaxOutput);
      
      // Check for high temperature alarm
      bAlarm := fCurrentTemp > fHighAlarmLimit;
  ELSE
      // Reset outputs when disabled
      fHeaterOutput := 0.0;
      fIntegral := 0.0;
      bAlarm := FALSE;
  END_IF
  
  (* 
  This function block implements a simple PI (Proportional-Integral) controller
  for temperature regulation. It calculates the appropriate heater output
  based on the difference between the setpoint and current temperature.
  The control parameters (Kp and Ki) can be tuned for optimal performance.
  *)
  
  // Suggested TwinCAT 3 features and techniques:
  // 1. Use structured error handling with TwinCAT 3 ErrorIDs for robust operation.
  // 2. Implement this function block in a TwinCAT 3 TcCOM object for better modularity.
  // 3. Consider using LREAL instead of REAL for higher precision in calculations.<|endoftext|>
  