Conveyor Belt Systems for Automotive

PROGRAM CONVEYOR_BELT_VARIABLE_SPEED_CONTROL
VAR
    // Inputs
    emergency_stop : BOOL;
    load_sensor : BOOL;
    upstream_ready : BOOL;
    downstream_ready : BOOL;

    // Analog Inputs
    belt_speed_fb : REAL;  // 0-100% speed feedback
    load_weight : REAL;     // Weight in kg

    // Outputs
    vfd_enable : BOOL;
    vfd_speed_sp : REAL;   // Speed setpoint 0-100%

    // Internal Variables
    target_speed : REAL := 50.0;
    ramp_rate : REAL := 5.0;  // %/second
    overload_limit : REAL := 500.0;  // kg


    // Production Metrics
    Takt_Time : TIME := T#60s;  // Target time per unit
    Cycle_Start_Time : TIME;
    Actual_Cycle_Time : TIME;
    Cycle_Time_OK : BOOL;

    // OEE (Overall Equipment Effectiveness) Tracking
    Availability_Percent : REAL;
    Performance_Percent : REAL;
    Quality_Percent : REAL;
    OEE_Percent : REAL;

    // Production Counters
    Units_Produced_Shift : INT := 0;
    Good_Parts_Count : INT := 0;
    Reject_Parts_Count : INT := 0;
    Rework_Parts_Count : INT := 0;

    // Downtime Tracking
    Downtime_Seconds : INT := 0;
    Downtime_Reason : STRING[50];
    Last_Downtime_Start : DATE_AND_TIME;

    // Andon System
    Andon_Status : INT;  // 0=Green, 1=Yellow, 2=Red
    Line_Stop_Request : BOOL;
    Material_Shortage : BOOL;
    Quality_Issue : BOOL;
    Maintenance_Required : BOOL;

    // Just-In-Time Integration
    Upstream_Buffer_Count : INT;
    Downstream_Buffer_Count : INT;
    Material_Call_Signal : BOOL;

    // Quality Gates
    Vision_Inspection_Pass : BOOL;
    Torque_Verification_Pass : BOOL;
    Dimension_Check_Pass : BOOL;
    All_Quality_Checks_Pass : BOOL;
END_VAR

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

// Emergency stop handling
IF NOT emergency_stop THEN
    vfd_enable := FALSE;
    vfd_speed_sp := 0.0;
    RETURN;
END_IF;

// Load-based speed adjustment
IF load_weight > overload_limit THEN
    target_speed := 30.0;  // Reduce speed when overloaded
ELSIF upstream_ready AND downstream_ready THEN
    target_speed := 80.0;  // Full speed when clear
ELSE
    target_speed := 50.0;  // Medium speed otherwise
END_IF;

// Ramp speed setpoint smoothly
IF vfd_speed_sp < target_speed THEN
    vfd_speed_sp := MIN(vfd_speed_sp + (ramp_rate * 0.1), target_speed);
ELSIF vfd_speed_sp > target_speed THEN
    vfd_speed_sp := MAX(vfd_speed_sp - (ramp_rate * 0.1), target_speed);
END_IF;

vfd_enable := TRUE;

// ==========================================
// AUTOMOTIVE SPECIFIC LOGIC
// ==========================================

    // Takt Time Monitoring for Lean Production
    IF Cycle_State = CYCLE_START THEN
        Cycle_Start_Time := CURRENT_TIME();
    ELSIF Cycle_State = CYCLE_COMPLETE THEN
        Actual_Cycle_Time := CURRENT_TIME() - Cycle_Start_Time;
        Cycle_Time_OK := (Actual_Cycle_Time <= Takt_Time);

        IF NOT Cycle_Time_OK THEN
            Andon_Status := 1;  // Yellow - Behind takt
        END_IF;
    END_IF;

    // OEE Calculation
    // Availability = (Operating Time - Downtime) / Operating Time
    Availability_Percent := ((Shift_Time - Downtime_Seconds) / Shift_Time) * 100.0;

    // Performance = (Actual Production / Target Production) * 100
    Performance_Percent := (Units_Produced_Shift / Target_Units_Shift) * 100.0;

    // Quality = (Good Parts / Total Parts) * 100
    IF Units_Produced_Shift > 0 THEN
        Quality_Percent := (Good_Parts_Count / Units_Produced_Shift) * 100.0;
    END_IF;

    // OEE = Availability × Performance × Quality
    OEE_Percent := (Availability_Percent * Performance_Percent * Quality_Percent) / 10000.0;

    // Andon Board Control - Visual Management
    IF Emergency_Stop OR Critical_Fault THEN
        Andon_Status := 2;  // Red - Line stop
        Downtime_Reason := 'EMERGENCY_STOP';

    ELSIF Material_Shortage THEN
        Andon_Status := 2;  // Red - Material needed
        Line_Stop_Request := TRUE;
        Downtime_Reason := 'MATERIAL_SHORTAGE';

    ELSIF Quality_Issue THEN
        Andon_Status := 1;  // Yellow - Quality alert
        Downtime_Reason := 'QUALITY_ISSUE';

    ELSIF Maintenance_Required THEN
        Andon_Status := 1;  // Yellow - Maintenance needed

    ELSE
        Andon_Status := 0;  // Green - Normal operation
    END_IF;

    // Just-In-Time Material Pull System
    IF Upstream_Buffer_Count < Min_Buffer_Level THEN
        Material_Call_Signal := TRUE;
        // Signal upstream process to send material
    END_IF;

    IF Downstream_Buffer_Count > Max_Buffer_Level THEN
        Production_Enable := FALSE;
        // Stop production to prevent overproduction (muda)
    END_IF;

    // Quality Gate Verification
    All_Quality_Checks_Pass := Vision_Inspection_Pass
                               AND Torque_Verification_Pass
                               AND Dimension_Check_Pass;

    IF NOT All_Quality_Checks_Pass THEN
        Reject_Parts_Count := Reject_Parts_Count + 1;
        Quality_Issue := TRUE;
        // Activate reject station
    ELSE
        Good_Parts_Count := Good_Parts_Count + 1;
    END_IF;

    Units_Produced_Shift := Good_Parts_Count + Reject_Parts_Count;

// ==========================================
// AUTOMOTIVE SAFETY INTERLOCKS
// ==========================================

    // Production Enable Conditions
    Production_Allowed := NOT Line_Stop_Request
                          AND NOT Material_Shortage
                          AND (Andon_Status <> 2)
                          AND (Downstream_Buffer_Count < Max_Buffer_Level)
                          AND NOT Emergency_Stop;

    // Quality Interlock
    IF NOT All_Quality_Checks_Pass THEN
        // Part routed to reject bin automatically
        Part_Accept_Gate := FALSE;
        Part_Reject_Gate := TRUE;
    END_IF;

    // Cycle Time Violation Alert
    IF Actual_Cycle_Time > (Takt_Time * 1.1) THEN
        // 10% over takt time triggers investigation
        Cycle_Time_Alarm := TRUE;
    END_IF;