Preventing Valve Block Icon Blinking During Local and Logic State Changes in SIMATIC PCS 7 APL

In SIMATIC PCS 7 Advanced Process Library (APL), a valve block icon that continuously blinks during local operation or logic-driven state changes—even after feedback monitoring (MonTiDyn, V_Monitor, M_Monitor) is disabled—occurs because the icon's dynamic animation script detects a mismatch between the commanded control state and physical limit switch feedback. Disabling monitoring parameters only suppresses alarm logging messages, not visual mismatch animations. To resolve this, configure the valve block for Local Tracking Mode by setting parameter LocalSetting = 2 or LocalSetting = 4, which forces internal control states to track actual field positions while operating locally.

APL Block Icon Animation Logic and Discrepancy Detection

In SIMATIC PCS 7 Advanced Process Library (APL) technological blocks (such as VlvL, Vlv2WayL, VlvMotL), block icons displayed on WinCC mimic diagrams serve as high-visibility operational indicators.

The block icon animation evaluates two distinct data channels:
1. The Commanded State: The active output command generated by automatic logic (OpenAut, CloseAut) or operator manual commands (OpenMan, CloseMan).
2. The Feedback Position: The discrete inputs wired to field limit switches (FbkOpen, FbkClose).

When a discrepancy exists—such as the block command requesting OPEN while the physical limit switch reports CLOSED—the block icon triggers a flashing animation to warn operators that the valve is not in its commanded state.

Alarm Suppression vs Visual Mismatch Animation

A frequent source of engineering confusion is attempting to stop the icon from blinking by disabling feedback monitoring parameters:
* Setting MonTiDyn = 0 (Dynamic Monitoring Time) or MonTiStatic = 0 (Static Monitoring Time).
* Setting V_Monitor = 0 or M_Monitor = 0.

Why this fails:
Disabling monitoring parameters instructs the internal Alarm_8P engine to suppress diagnostic alarms (e.g. "Valve travel time error" will not appear in the alarm banner). However, it does not alter the graphic evaluation script! The block icon's dynamic color script continues to compare the commanded latch against physical feedback; as long as they disagree, the icon flashes continuously.

Understanding LocalSetting Tracking Modes in APL Valves

To stop unwanted blinking when equipment is operated locally from a field push-button station or local control box, APL incorporates Local Mode Tracking:

[LocalSetting Parameter Modes in APL Valve Blocks]
   │
   ├─► LocalSetting = 0: Local mode not used
   │
   ├─► LocalSetting = 1: Local mode via input signals (No tracking; blinks on mismatch)
   │
   ├─► LocalSetting = 2: Local mode with TRACKING via field signals
   │     • When LocalAct = 1: Control outputs track physical limit switches
   │     • Eliminates command-feedback discrepancy -> Stops icon blinking!
   │
   ├─► LocalSetting = 3: Local mode without tracking (Manual intervention required)
   │
   └─► LocalSetting = 4: Local mode with TRACKING via feedback signals
         • Internal manual/auto states mirror actual position automatically
         • Enables seamless, bumpless transfer back to Remote Auto mode

Configuring LocalSetting = 2 and LocalSetting = 4 in CFC

The table below details parameter configurations to eliminate blinking across common operational scenarios:

Operational ScenarioParameter to AdjustConfigured ValueBehavioral ResultField Handwheel / Local StationLocalSetting2 (Tracking via Field Signals)Internal command tracks limit switches; icon remains solid.Logic-Driven State ChangeFeature.Bit01 (Set startup characteristics)Block aligns internal states cleanly upon initialization.Bumpless Remote HandoverLocalSetting4 (Tracking via Feedback)When local mode drops, valve remains in current state.Bypass Travel Warning MessagesMonTiDynSet to realistic stroke time (e.g. 15.0s)Normal travel does not flash; only true stalls flash.

Verification

To confirm that the valve block icon stops blinking during local operation:
1. In the CFC chart containing VlvL, verify that LocalSetting is set to 2 or 4.
2. In WinCC Runtime, place the valve into Local Mode by asserting LocalLi = 1 or selecting Local from the faceplate.
3. Manually open or close the valve via the field local pushbuttons (or simulate FbkOpen = 1).
4. Observe the valve block icon on the process screen; confirm that the icon transitions smoothly to the solid open or closed color without blinking.
5. Switch the valve back to Remote / Auto mode; confirm that the transition occurs bumplessly without triggering feedback error alarms.

Limitations and Operational Precautions

Never configure LocalSetting = 2 or 4 without verifying that field limit switches (FbkOpen, FbkClose) are properly wired and functionally reliable. If tracking mode is enabled and a field limit switch bounces or fails open, the block will attempt to track an invalid state, causing state toggling. Always maintain end-position interlocks in the physical MCC circuit for personnel safety.

Engineer FAQ

Why did setting `MonTiDyn = 0` not stop the icon from blinking?

MonTiDyn = 0 disables only alarm generation in Alarm Logging. The graphic animation script in WinCC evaluates status word bits independently and continues blinking on state discrepancies.

What is the difference between `LocalSetting = 2` and `LocalSetting = 4`?

LocalSetting = 2 tracks field control signals wired directly to local open/close inputs. LocalSetting = 4 tracks the physical limit switch feedback signals (FbkOpen, FbkClose).

Can I force a valve block icon to stop blinking from WinCC Graphic Designer?

No. In APL, block icon dynamics are driven by status word bits (Status1, Status2) transmitted from the AS. Modifying Graphic Designer scripts will break standard APL library behavior.

Does `VlvMotL` support the same tracking modes as `VlvL`?

Yes. Both VlvL and VlvMotL share the standardized APL operating mode and tracking architecture, utilizing identical LocalSetting parameters.

Technical References

Related Tags

APL Valve
Block Icon Blinking
LocalSetting
VlvL
Feedback Monitoring

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Preventing Valve Block Icon Blinking During Local and Logic State Changes in SIMATIC PCS 7 APL