Wastewater Treatment for Municipal

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;


    // Infrastructure Monitoring
    Distribution_Pressure : REAL;
    Reservoir_Level : REAL;
    Pump_Station_Status : ARRAY[1..5] OF BOOL;

    // Remote Monitoring
    RTU_Communication : ARRAY[1..10] OF BOOL;  // Remote Terminal Units
    Telemetry_Update_Rate : TIME := T#30s;
    SCADA_Alarms : INT;

    // Emergency Response
    Boil_Water_Advisory : BOOL;
    Water_Main_Break : BOOL;
    Emergency_Mode : BOOL;
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;

// ==========================================
// MUNICIPAL SPECIFIC LOGIC
// ==========================================

    // Distribution System Monitoring
    IF Distribution_Pressure < Min_Distribution_Pressure THEN
        Low_Pressure_Alarm := TRUE;
        // Start backup pump
        Pump_Station_Status[Backup_Pump] := TRUE;
    END_IF;

    // SCADA Integration
    FOR i := 1 TO 10 DO
        IF NOT RTU_Communication[i] THEN
            SCADA_Alarms := SCADA_Alarms + 1;
            // Alert operator of communication loss
        END_IF;
    END_FOR;

    // Emergency Response
    IF Water_Main_Break THEN
        Emergency_Mode := TRUE;
        // Isolate affected zone
        Zone_Isolation_Valves := TRUE;
    END_IF;

// ==========================================
// MUNICIPAL SAFETY INTERLOCKS
// ==========================================

    Production_Allowed := NOT Emergency_Mode
                          AND NOT Boil_Water_Advisory
                          AND (Distribution_Pressure >= Min_Pressure);