Configuring Multi-Monitor Displays in SIMATIC PCS 7 OS: Resolving Off-Screen Windows and Quadro GPU Multi-Screen Alignment

In SIMATIC PCS 7 OS multi-monitor configurations (e.g., 4 screens), dialog windows like 'Trends Online' or faceplates open off-screen or on incorrect displays when Windows virtual desktop coordinates do not match the monitor layout defined in the WinCC OS Project Editor, or when mixing onboard motherboard video outputs with dedicated NVIDIA Quadro graphics cards. To resolve this, connect all four monitors exclusively to the dedicated NVIDIA Quadro GPU (disabling onboard video), align all four displays at identical resolution (e.g., 1280x1024 or 1920x1080) horizontally in Windows Display Settings with Monitor 1 as the primary desktop at origin (0,0), and match the layout identically in the OS Project Editor 'Layout' tab.

PCS 7 Multi-Monitor Architecture and Coordinate Calculation

In industrial control rooms, operators require expansive visual overviews across multiple physical monitors (typically 2, 3, or 4 displays per OS Client). SIMATIC PCS 7 provides native multi-monitor management through the OS Project Editor and Basic Process Control (BPC).

WinCC manages multiple monitors by treating the display surface as a unified virtual desktop rectangle. When an operator clicks a button on Screen 3 to open 'Trends Online' or an APL faceplate, the WinCC window manager script calculates the target window position by offsetting coordinates from the primary display origin (X=0, Y=0) based on the monitor geometry configured in the project. If there is any discrepancy between physical Windows display coordinates and the WinCC configuration, windows drop off-screen or appear on the wrong monitor.

The Pitfalls of Mixing Onboard Video with Dedicated GPUs

A frequent hardware misconfiguration occurs when commissioning a 4-monitor client station using a mix of video outputs (such as connecting two monitors to motherboard DVI-D ports and two monitors to an add-on NVIDIA Quadro P600 graphics card):

Disparate Graphics Drivers: Onboard Intel graphics and NVIDIA Quadro cards use completely separate display drivers with conflicting hardware acceleration layers. This creates subtle timing jitters and window coordinate translation errors.
Coordinate Offset and Inverted Vertical Stacking: Windows often places onboard displays below or offset from dedicated card displays in the virtual coordinate plane. If Monitor 3 has a negative or offset Y-coordinate, WinCC's calculation places popups into non-existent coordinate space, causing them to appear completely out of the visible viewing area.
Recommended Hardware Rule: All displays on a PCS 7 OS station must connect exclusively to outputs on the same dedicated multi-head graphics card (e.g., NVIDIA Quadro with 4 Mini-DisplayPort outputs). Motherboard onboard video must be disabled in the BIOS.

Windows Virtual Desktop Coordinates vs OS Project Editor Layout

WinCC OS Project Editor supports specific geometric layouts under its Layout tab:

1 x 2: Two displays side-by-side horizontally.
1 x 4: Four displays side-by-side in a single horizontal row.
2 x 2: Quad-display arrangement in a 2-high by 2-wide matrix.

For WinCC to calculate popup coordinates correctly:

Primary Display (Monitor 1): Must be set to the far top-left monitor in Windows Display Settings. This ensures that the virtual origin (0,0) sits at the upper-left corner of the primary display.
Strict Horizontal Alignment: In Windows Display Settings, all four monitors must be snapped tightly together along their top borders with zero vertical pixel offsets.
Resolution Parity: All four monitors must run at the exact same native resolution (e.g., all 1280x1024 or all 1920x1080) and identical DPI scaling (100%).

Step-by-Step Multi-Monitor Alignment and Configuration Procedure

Follow this procedure to correct off-screen dialogs and align a 4-screen PCS 7 client:

Hardware Re-cabling: Disconnect all monitors from onboard motherboard DVI ports. Connect all four monitors directly to the four ports of the NVIDIA Quadro graphics card using active DisplayPort-to-DVI/HDMI adapters.
Configure Windows Display Settings:
- Right-click the desktop and select Display Settings.
- Click Identify to determine monitor numbering (1, 2, 3, 4).
- Drag the monitor boxes so they form a continuous horizontal line: [1] [2] [3] [4].
- Select Monitor 1 and check the box: Make this my main display.
- Ensure all four screens are set to identical resolution (e.g., 1280 x 1024) and scaling is set to 100%.
Configure WinCC OS Project Editor:
- Open the OS project in WinCC Explorer. Open OS Project Editor.
- In the Layout tab, select the layout matching your Windows arrangement (e.g., SIMATIC Standard 1920*1080 1x4 or SIMATIC Standard 1280*1024 1x4).
- Click OK to regenerate system pictures (@SCREEN.PDL).
Verify MonitorConfiguration.xml: Inspect <OS_Project>\GraCS\MonitorConfiguration.xml to verify that monitor coordinates Left, Top, Width, and Height match Windows coordinates exactly.

Multi-Monitor Layout Comparison Matrix

The following table compares multi-monitor configurations in SIMATIC PCS 7 OS:

Layout FormatTotal ScreensRecommended GPUWindows Coordinate GridIdeal Control Room Application1 x 2 Horizontal2 ScreensDual-head GPU or QuadroMon 1 (0,0), Mon 2 (1920,0)Standard operator console desk1 x 4 Horizontal4 ScreensNVIDIA Quadro (4-port)Mon 1 (0,0), Mon 2 (1920,0), Mon 3 (3840,0), Mon 4 (5760,0)Wide panoramic operator workstation2 x 2 Matrix4 Screens (2x2)NVIDIA Quadro (4-port)Mon 1 (0,0), Mon 2 (1920,0), Mon 3 (0,1080), Mon 4 (1920,1080)Stacked overview video wallMixed Onboard/GPU4 ScreensDisparate DriversIrregular offsets / Negative YStrictly Forbidden / Prone to off-screen bugs

Verification

Verify multi-monitor operation through the following test sequence:

Activate WinCC Runtime on the OS Client. Confirm that the overview screen, navigation bar, and alarm line span across all four monitors without stretching or black gaps.
Click the 'Trend System' or 'Trends Online' button on Monitor 3. Verify that the trend window opens centered directly on Monitor 3, not on Monitor 1 or off-screen.
Click a block icon on Monitor 1, Monitor 2, and Monitor 4. Confirm that faceplates open adjacent to their respective icons on the correct screen.
Test operator window dragging. Confirm that windows drag smoothly across monitor boundaries without jumping or disappearing.

Limitations and Operational Precautions

Consider these operational rules when engineering multi-monitor setups:

Never Enable NVIDIA Surround / Mosaic: Do not combine the monitors into a single virtual super-display using NVIDIA Mosaic or Surround mode. WinCC BPC requires individual monitor handles managed by Windows, not a single giant canvas.
DPI Scaling Must Be 100%: Windows DPI scaling (e.g., 125% or 150%) must be disabled on all screens; mixing DPI scaling causes severe coordinate distortion in WinCC faceplate scripts.
Sleep and Power Management: In Windows Power Options, disable monitor sleep and screen savers. If Windows powers down DisplayPort monitors, it temporarily collapses the desktop to a single screen, scrambling open faceplates.

Engineer FAQ

Where does WinCC store the multi-monitor geometry configuration?

WinCC stores monitor coordinates in MonitorConfiguration.xml located in the OS project's GraCS directory.

What happens if Windows puts DisplayPort monitors to sleep?

DisplayPort communication drops the monitor connection upon sleep, causing Windows to reconfigure the desktop to a single display and scrambling WinCC picture windows.