Allen-Bradley Structured Text for Sensor Integration

(* Allen-Bradley Studio 5000 (formerly RSLogix 5000) - Sensor Integration Control *)
(* Structured Text Implementation for Universal *)
(* Tag-based architecture necessitates consistent naming conventions impr *)

PROGRAM PRG_SENSOR_INTEGRATION_Control

VAR
    (* State Machine Variables *)
    eState : E_SENSOR_INTEGRATION_States := IDLE;
    bEnable : BOOL := FALSE;
    bFaultActive : BOOL := FALSE;

    (* Timers *)
    tonDebounce : TON;
    tonProcessTimeout : TON;
    tonFeedbackCheck : TON;

    (* Counters *)
    ctuCycleCounter : CTU;

    (* Process Variables *)
    rAnalogsensors420mA010V : REAL := 0.0;
    rNotapplicablefocusoninputprocessing : REAL := 0.0;
    rSetpoint : REAL := 100.0;
END_VAR

VAR CONSTANT
    (* Universal Process Parameters *)
    C_DEBOUNCE_TIME : TIME := T#500MS;
    C_PROCESS_TIMEOUT : TIME := T#30S;
    C_BATCH_SIZE : INT := 50;
END_VAR

(* Input Conditioning *)
tonDebounce(IN := bStartButton, PT := C_DEBOUNCE_TIME);
bEnable := tonDebounce.Q AND NOT bEmergencyStop AND bSafetyOK;

(* Main State Machine - Pattern: State machine implementation in Allen-Br *)
CASE eState OF
    IDLE:
        rNotapplicablefocusoninputprocessing := 0.0;
        ctuCycleCounter(RESET := TRUE);
        IF bEnable AND rAnalogsensors420mA010V > 0.0 THEN
            eState := STARTING;
        END_IF;

    STARTING:
        (* Ramp up output - Gradual start *)
        rNotapplicablefocusoninputprocessing := MIN(rNotapplicablefocusoninputprocessing + 5.0, rSetpoint);
        IF rNotapplicablefocusoninputprocessing >= rSetpoint THEN
            eState := RUNNING;
        END_IF;

    RUNNING:
        (* Sensor Integration active - Sensor integration involves connecting various mea *)
        tonProcessTimeout(IN := TRUE, PT := C_PROCESS_TIMEOUT);
        ctuCycleCounter(CU := bCyclePulse, PV := C_BATCH_SIZE);

        IF ctuCycleCounter.Q THEN
            eState := COMPLETE;
        ELSIF tonProcessTimeout.Q THEN
            bFaultActive := TRUE;
            eState := FAULT;
        END_IF;

    COMPLETE:
        rNotapplicablefocusoninputprocessing := 0.0;
        (* Log production data - High-resolution data logging captures process variables into controller memory using circular buffer structures before uploading to historians via OPC-UA or database writes. Create logging UDT: DataLog_Type containing Timestamp (DINT), Values (ARRAY[1..50] OF REAL), TriggerSource (DINT), implementing as DataLog : ARRAY[0..9999] OF DataLog_Type providing 10,000 sample buffer. Write pointer increments with each sample: WritePointer := (WritePointer + 1) MOD 10000 wrapping to zero when reaching array limit, automatically overwriting oldest data. Triggered logging detects alarm conditions preserving pre-trigger and post-trigger data for root cause analysis: trigger on high temperature alarm capturing 100 samples before and 500 samples after providing context. Timestamp using GSV (Get System Value) retrieving WallClockTime ensures synchronized time correlation across multiple controllers via CIP Sync (IEEE 1588). Analog array sampling collects multiple tags simultaneously: FOR index := 1 TO 50 DO DataLog[WritePointer].Values[index] := ProcessValues[index] END_FOR. Background upload task runs periodically transferring logged data to SQL database via MSG (Message) instruction using CIP Generic service codes or ASCII write to CSV files on CompactFlash card. Data compression implements deadband filtering storing samples only when values change beyond threshold reducing storage requirements: IF ABS(CurrentValue - LastLoggedValue) > Deadband THEN log sample. Integration with FactoryTalk Historian automatically collects tag changes without controller programming overhead, providing web-based trending and analytics with 10+ year retention. Recipe correlation links production data to batch IDs enabling product genealogy tracing from raw materials through finished goods. Energy logging totalizes consumption per production unit calculating specific energy consumption (kWh per ton) identifying optimization opportunities. Safety event logging in GuardLogix captures all safety input states, bypass activations, and forced states with tamper-proof timestamps meeting IEC 61508 documentation requirements. *)
        eState := IDLE;

    FAULT:
        rNotapplicablefocusoninputprocessing := 0.0;
        (* Alarm management in Allen-Bradley uses structured UDTs creating alarm objects with consistent properties: Active (BOOL), Acknowledged (BOOL), Severity (DINT 1-10), Timestamp (DINT), Description (STRING), and InstructionsText (STRING). Alarm array implementation: Plant_Alarms : ARRAY[1..500] OF Alarm_Type consolidating all alarms in structured format. Alarm scanning routine iterates through conditions: IF TankLevel > HighLimit AND NOT Plant_Alarms[101].Active THEN Plant_Alarms[101].Active := TRUE; Plant_Alarms[101].Timestamp := GSV(WallClockTime). Integration with FactoryTalk Alarms and Events uses produced tags automatically publishing alarm array to HMI workstations for filtering, acknowledgment, and historical logging. Alarm priority hierarchy ensures critical alarms (Severity 9-10) override lower priority warnings with distinct audible tones and color coding: safety=red, process=yellow, information=blue. Shelving functionality temporarily suppresses nuisance alarms during commissioning or maintenance without program modification, managed through HMI with automatic unshelving after timeout period. Deadband logic prevents alarm chattering when analog values oscillate near setpoint: Activate alarm when value exceeds limit+2%, deactivate when falls below limit-2%. Alarm flooding protection counts alarm activations within 60-second window, displaying 'Multiple Alarms' summary preventing operator overwhelm during cascading failures. First-out detection latches initial alarm in sequence of related alarms identifying root cause: bearing temperature alarm before motor overload before production stoppage. Integration with SMS/email uses FactoryTalk Notification sending formatted messages to on-call maintenance personnel for critical alarms outside business hours. Audit trails log all alarm occurrences, acknowledgments, and user actions to secure historian databases meeting regulatory compliance requirements in pharmaceutical and food industries. *)
        IF bFaultReset AND NOT bEmergencyStop THEN
            bFaultActive := FALSE;
            eState := IDLE;
        END_IF;
END_CASE;

(* Safety Override - Always executes *)
IF bEmergencyStop OR NOT bSafetyOK THEN
    rNotapplicablefocusoninputprocessing := 0.0;
    eState := FAULT;
    bFaultActive := TRUE;
END_IF;

END_PROGRAM