Elevator Control Systems for Manufacturing

PROGRAM PLC_CONTROL_LOGIC_EXAMPLE
VAR
    // Inputs
    start_button : BOOL;
    stop_button : BOOL;
    system_ready : BOOL;
    error_detected : BOOL;

    // Outputs
    motor_run : BOOL;
    alarm_signal : BOOL;

    // Internal State
    system_state : INT := 0; // 0=Idle, 1=Running, 2=Error
    runtime_counter : INT := 0;


    // Production Tracking
    Production_Count : INT := 0;
    Target_Production : INT := 1000;
    Production_Rate : REAL;  // Units per hour
    Shift_Start_Time : DATE_AND_TIME;

    // Predictive Maintenance
    Vibration_Level : REAL;  // mm/s RMS
    Bearing_Temperature : REAL;
    Runtime_Hours : REAL;
    Maintenance_Due : BOOL;
    Next_PM_Date : DATE;

    // Energy Monitoring
    Power_Consumption : REAL;  // kW
    Energy_Total_Daily : REAL; // kWh
    Energy_Per_Unit : REAL;    // kWh per part
    Peak_Demand_Alarm : BOOL;

    // Material Tracking
    Material_Batch_ID : STRING[20];
    Material_Quantity : REAL;
    Scrap_Count : INT;
    Scrap_Percentage : REAL;

    // Machine Status
    Machine_State : STRING[20];
    Idle_Time : TIME;
    Run_Time : TIME;
    Utilization_Percent : REAL;
END_VAR

// ==========================================
// BASE APPLICATION LOGIC
// ==========================================

CASE system_state OF
    0: // Idle state
        motor_run := FALSE;
        alarm_signal := FALSE;

        IF start_button AND system_ready AND NOT error_detected THEN
            system_state := 1;
        END_IF;

    1: // Running state
        motor_run := TRUE;
        alarm_signal := FALSE;
        runtime_counter := runtime_counter + 1;

        IF stop_button OR error_detected THEN
            system_state := 2;
        END_IF;

    2: // Error state
        motor_run := FALSE;
        alarm_signal := TRUE;

        IF stop_button AND NOT error_detected THEN
            system_state := 0;
            runtime_counter := 0;
        END_IF;
END_CASE;

// ==========================================
// MANUFACTURING SPECIFIC LOGIC
// ==========================================

    // Production Rate Calculation
    Production_Rate := Production_Count / Runtime_Hours;

    // Utilization Tracking
    Utilization_Percent := (Run_Time / (Run_Time + Idle_Time)) * 100.0;

    // Predictive Maintenance Alert
    IF (Vibration_Level > Normal_Vibration * 2.0) OR
       (Bearing_Temperature > Normal_Temp + 20.0) OR
       (Runtime_Hours >= PM_Interval_Hours) THEN
        Maintenance_Due := TRUE;
        Machine_State := 'MAINTENANCE_REQUIRED';
    END_IF;

    // Energy Efficiency Monitoring
    Energy_Per_Unit := Energy_Total_Daily / Production_Count;

    IF Power_Consumption > Peak_Demand_Limit THEN
        Peak_Demand_Alarm := TRUE;
        // Implement load shedding if needed
    END_IF;

    // Scrap Rate Tracking
    Scrap_Percentage := (Scrap_Count / Production_Count) * 100.0;

    IF Scrap_Percentage > Target_Scrap_Percent THEN
        Quality_Alert := TRUE;
    END_IF;

// ==========================================
// MANUFACTURING SAFETY INTERLOCKS
// ==========================================

    // Production Enable
    Production_Allowed := NOT Maintenance_Due
                          AND (Material_Quantity > Min_Material)
                          AND NOT Emergency_Stop
                          AND NOT Peak_Demand_Alarm;