Configuring Mouse Wheel Behavior and Screen Navigation in SIMATIC PCS 7 WinCC Runtime

In SIMATIC PCS 7 WinCC Runtime, native mouse wheel scrolling cannot be assigned to sequential process picture (page) navigation. WinCC strictly reserves mouse wheel events at the operating system and graphics engine level for Decluttering, Extended Zooming, and Panning within process pictures, as well as vertical scrolling inside active table and alarm controls. Implementing page switching via mouse wheel scrolling would create severe operational hazards by accidentally changing plant overviews during pan/zoom maneuvers. To navigate between pictures efficiently, engineers must utilize the Plant Hierarchy Picture Tree Navigator, the standard PCS 7 navigation toolbar buttons (Back, Forward, Recall), Loop-in-Alarm shortcuts, or user-configurable hotkeys.

Mouse Wheel Functional Allocation in WinCC Runtime

In industrial Human Machine Interfaces (HMI) governed by process safety standards, input peripheral interactions must be predictable and deterministic. In SIMATIC PCS 7 OS (WinCC V7.x), the interaction model for the mouse wheel is tightly integrated into the graphics runtime subsystem (Graphics Runtime).

When mouse wheel events occur within a process window, the WinCC runtime dispatcher routes the input according to the active object and runtime configuration:
1. Focus on Controls: If the mouse pointer hovers over a WinCC AlarmControl, TrendControl, or TableControl, rolling the mouse wheel scrolls through alarm lists, historical data tables, or trend curves vertically.
2. Focus on Process Canvas: If the mouse pointer is over the general picture canvas, mouse wheel scrolling triggers Extended Zooming (zooming in or out centered on the cursor position) or Decluttering (dynamically displaying or hiding technical details based on the zoom factor).
3. Panning with Wheel Click: Depressing the mouse wheel (middle click) and dragging activates 2D panning across expansive process graphics.

Why Sequential Page Navigation via Mouse Wheel is Restricted

Process control engineers occasionally receive requests from plant operators to allow rolling the mouse wheel to flip sequentially through process screens (similar to flipping pages in a PDF viewer or web browser).

Siemens strictly omits native page-flipping via mouse wheel in WinCC Runtime due to critical operational and architectural constraints:
- Catastrophic Accidental Navigation: In a chemical plant or refinery, an operator attempting to zoom in on a distillation column to read a critical temperature value could inadvertently trigger a picture flip if the pointer drifts slightly, losing visual contact with the active process unit during an upset.
- Conflict with Embedded Controls: If an operator scrolls to inspect unacknowledged alarms in @AlarmNew.pdl, ambiguous event capture could switch the main process picture instead of scrolling the alarm grid.
- Absence of Exposed Mouse Wheel Events: The WinCC Graphics Designer object model does not expose an OnMouseWheel script trigger in standard picture windows or static graphics objects. Attempting to intercept mouse wheel events using low-level Windows API hooks (e.g., SetWindowsHookEx) bypasses WinCC message queuing, causing graphics thread hangs and violating industrial software validation.

Configuring Zooming, Panning, and Decluttering

To configure the supported mouse wheel functions in WinCC Explorer:

Step 1: Enable Zoom and Panning in Computer Properties

Open WinCC Explorer on the Engineering Station or OS node.
Right-click the local computer object and select Properties.
Select the Graphics Runtime tab.
Locate the section Turn on zoom functions in runtime.
Enable the following options:
- Extended zoom: Enables zooming centered on the mouse pointer using Ctrl + Mouse Wheel or standard mouse wheel scrolling.
- Panning: Enables 2D graphic dragging by holding down the middle mouse wheel button or Shift + Left Click.
- Display decluttering: Enables progressive detail display linked to the zoom level.

Step 2: Configure Decluttering Layers in Graphics Designer

Open a process picture (.pdl) in Graphics Designer.
Select an equipment symbol or detailed measurement text.
In the Object Properties window, select Miscellaneous > Decluttering.
Set the Minimum Zoom Factor (e.g., 150%) and Maximum Zoom Factor (e.g., 400%).
In runtime, rolling the mouse wheel zooms into the unit; when the zoom factor crosses $150\%$, the high-detail instrumentation tags automatically appear.

Approved Picture Navigation Methodologies

SIMATIC PCS 7 provides standardized, ergonomic navigation structures designed to facilitate rapid operator response without relying on non-standard mouse gestures:

Picture Tree Navigator (PTN): Hierarchical navigation bar automatically generated from the Plant Hierarchy. Operators access areas, units, and equipment with a single click.
Navigation Toolbar Buttons (@Buttons11.pdl / @Buttons12.pdl):
- Previous Picture (Back): Returns to the previously viewed picture in the historical stack.
- Next Picture (Forward): Advances through the forward history stack.
- Recall Picture: Cycles through previously opened pictures.
Loop-in-Alarm: When an alarm occurs, clicking the 'Loop-in-Alarm' button in the alarm banner immediately navigates to the exact process graphic containing the faulted block icon and centers it on screen.
Custom Scripted Buttons: For sequential training or sequential equipment lines, place dedicated forward/backward navigation buttons containing standard C-actions:

// Navigate to specific process picture
OpenPicture("Unit_102.pdl");

WinCC Mouse Wheel and Navigation Function Matrix

The following matrix details the operational functions of mouse interactions in WinCC Runtime:

User InteractionCanvas FocusActive Control Focus (Alarm/Trend)System Configuration RequirementMouse Wheel RollExtended Zooming / DeclutteringVertical row / trend scrollingEnabled in Computer Properties > Graphics RuntimeCtrl + Mouse WheelHigh-precision incremental zoomStandard control zoom / scaleDefault Windows Graphics Runtime behaviorMiddle Wheel Click + Drag2D Panning across canvasGrid scrollingPanning enabled in Computer PropertiesPicture Navigation ButtonsOpens Next/Previous screenUnaffectedStandard PCS 7 @Buttons11.pdl runtime toolbarLoop-in-Alarm ClickOpens faulted unit pictureUnaffectedConfigured block icon and message properties

Verification

To confirm that mouse wheel zooming, panning, and navigation function correctly:
1. Launch WinCC Runtime.
2. Open a process graphic containing equipment symbols and embedded table controls.
3. Place the cursor over the open canvas and roll the mouse wheel: Verify that the picture zooms smoothly in and out without changing screens.
4. Depress the mouse wheel and drag: Confirm that the canvas pans smoothly across hidden boundaries.
5. Move the cursor over an active AlarmControl list and roll the mouse wheel: Confirm that the alarm rows scroll vertically while the background process graphic remains static.
6. Click the 'Back' and 'Forward' buttons on the PCS 7 bottom toolbar: Verify that the operator history navigation correctly cycles through recently opened pictures.

Limitations and Operational Precautions

Observe the following operational constraints:
- Do Not Use Third-Party Mouse Utilities: Software utilities that re-map mouse wheel events to keyboard strokes (such as Page Up / Page Down) must never be installed on production OS clients. They disrupt normal alarm acknowledgment workflows and create unvalidated software states.
- Multi-Monitor Systems: In multi-screen operator stations, ensure mouse wheel zooming is constrained to the active monitor canvas without crossing virtual screen boundaries.
- Touch Screen Workstations: On industrial touch monitors where physical mouse wheels are absent, provide visible on-screen pan/zoom controls and explicit navigation pushbuttons.

Engineer FAQ

Can I write a C or VBS script to capture the mouse wheel in Graphics Designer?

No. WinCC Graphics Designer does not expose a window-level mouse wheel event in its script interface. Event handling is restricted to mouse clicks (press, release) and cursor movement.

What is Decluttering in WinCC Runtime?

Decluttering is an automated graphics decluttering feature where complex details (such as signal names, instrument tags, and interlock lines) are hidden at overview zoom levels and become visible only when an operator zooms in using the mouse wheel.

How do I return to the previous screen if I accidentally clicked away?

Click the 'Back' button (left-pointing arrow) on the standard PCS 7 operator toolbar located at the bottom of the screen. WinCC maintains an internal stack of the last 10 visited process pictures.