2025-08-12
Siemens SCL Programming Upgraded Version: 12 Industrial Practical Cases
Case 1: Motor Start-Stop Control
FUNCTION_BLOCK FB_MotorControl VAR_INPUT StartButton: BOOL; StopButton: BOOL; OverloadSignal: BOOL; END_VAR VAR_OUTPUT RunningStatus: BOOL; FaultIndicator: BOOL; END_VAR BEGIN // Start-Stop Logic IF StartButton AND NOT StopButton AND NOT OverloadSignal THEN RunningStatus := TRUE; ELSIF StopButton OR OverloadSignal THEN RunningStatus := FALSE; END_IF; // Fault Indication FaultIndicator := OverloadSignal; END_FUNCTION_BLOCK
scl
Case 3: PID Temperature Control
FUNCTION_BLOCK FB_TempControl VAR_INPUT Setpoint: REAL; ProcessValue: REAL; END_VAR VAR_OUTPUT ControlOutput: REAL; END_VAR VAR Kp: REAL := 2.0; Ki: REAL := 0.05; Kd: REAL := 0.5; IntegralTerm: REAL := 0; LastError: REAL := 0; Timer: TON; END_VAR BEGIN // Execute periodically (100ms) Timer(IN := NOT Timer.Q, PT := T#100ms); IF Timer.Q THEN VAR Error := Setpoint - ProcessValue; IntegralTerm := IntegralTerm + Error; VAR DerivativeTerm := Error - LastError; LastError := Error; ControlOutput := Kp * Error + Ki * IntegralTerm + Kd * DerivativeTerm; ControlOutput := LIMIT(0.0, ControlOutput, 100.0); Timer(IN := FALSE); END_IF; END_FUNCTION_BLOCK
scl
Case 5: Safety Gate Interlock Control
FUNCTION_BLOCK FB_SafetyGate VAR_INPUT Gate1Closed, Gate2Closed: BOOL; EStopButton: BOOL; ResetButton: BOOL; END_VAR VAR_OUTPUT SafetyStatus: BOOL; END_VAR VAR LockoutStatus: BOOL := FALSE; LockoutTimer: TON; END_VAR BEGIN // Safety condition VAR AllGatesClosed := Gate1Closed AND Gate2Closed; // Emergency stop highest priority IF EStopButton THEN SafetyStatus := FALSE; LockoutStatus := TRUE; LockoutTimer(IN := TRUE, PT := T#10S); RETURN; END_IF; // Unlock logic IF ResetButton AND LockoutStatus AND LockoutTimer.Q THEN LockoutStatus := FALSE; END_IF; // Normal operation IF NOT LockoutStatus THEN SafetyStatus := AllGatesClosed; END_IF;