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Controller: Conveyor_Line3_Main · Studio 5000 v32

This program controls a three-zone product conveyor system serving a packaging line. The controller manages product accumulation, zone-to-zone transfer logic, and jam detection across three independently driven belt segments. Product presence is monitored via photoelectric sensors on each zone, and all belt drives are variable-frequency controlled through the VFD_Cmd tag group.

The program is organized into four routines: MainRoutine handles the primary sequencing state machine, Safety_Reset manages E-stop and light curtain resets, Zone_Control contains the per-zone accumulation logic, and Faults handles fault logging and HMI notification. Overall structure is reasonable, though routine separation could be cleaner — some zone logic is duplicated across MainRoutine and Zone_Control.

MainRoutine (RLL) — Entry point for all scan-cycle logic. Manages the primary state machine with states: Idle (0), Running (1), Faulted (2), E-Stop (3). Transitions are gated by Sys_Ready and EStop_OK conditions. Approximately 48 rungs. The state machine logic is readable but the fault transition rungs lack inline comments.

Zone_Control (RLL) — Handles accumulation logic for Zones 1–3. Each zone evaluates downstream sensor state before enabling its belt drive output. A 500ms on-delay timer (Zone_X_Delay) prevents rapid re-enabling after a jam clear. Logic is functional but zones are handled with copy-pasted rung structures rather than AOIs.

Safety_Reset (RLL) — 12-rung routine managing E-stop reset sequence. Requires HMI acknowledgment (HMI_Reset_Cmd) and confirmed safety relay state before re-enabling drive enables. Correctly sequences the reset with a one-scan pulse to prevent false resets.

Includes everything in the Documentation tier — program overview, full routine breakdowns, and tag dictionary. See Documentation sample for examples.

[High] Rename cryptic tags before next maintenance window. Create a tag rename plan for the ~40 tags in Zone_Control using the existing naming pattern from Safety_Reset as a reference model. A tag cross-reference export from Studio 5000 will identify all rung usages.

[High] Add VFD fault rung logic to Zone_Control. Evaluate each drive fault input and add transitions to Fault_Code = 2 with a descriptive fault message to the HMI fault table. Without this, drive trips will cause unexplained production stops.

[Medium] Refactor zone logic into an Add-On Instruction. A Zone_Accumulate AOI with parameters for sensor input, belt output, and delay preset would eliminate the 3x code duplication and make future zone additions trivial. Estimated development: 2–3 hours.

[Low] Audit and remove unused tags. Run a cross-reference report in Studio 5000 and remove confirmed unused tags. Document any removed tags in a change log.

Includes all Documentation and Audit content — program overview, routine breakdowns, tag dictionary, code quality audit, and prioritized recommendations. See those sample previews for examples.

Zone_Control — Proposed AOI Refactor

Current implementation duplicates 12 rungs across 3 zones. Proposed: a Zone_Accumulate Add-On Instruction with the following interface:

// Zone_Accumulate AOI
// Parameters:
//   InProductPresent  : BOOL  - Photoelectric sensor input
//   InDownstreamClear : BOOL  - Downstream zone available
//   InFaultClear      : BOOL  - Fault reset permissive
//   OutBeltEnable     : BOOL  - Belt drive enable output
//   OutFaultActive    : BOOL  - Fault status to MainRoutine

IF InFaultClear AND NOT OutFaultActive THEN
    // Re-enable delay after jam clear
    ReenableTimer.PRE := 500;
    ReenableTimer.EN  := TRUE;

    IF ReenableTimer.DN THEN
        IF InProductPresent AND InDownstreamClear THEN
            OutBeltEnable := TRUE;
        ELSE
            OutBeltEnable := FALSE;
        END_IF;
    END_IF;
ELSE
    OutBeltEnable := FALSE;
    ReenableTimer.EN := FALSE;
END_IF;