Resolving WinCC OS Server 'Start Screen Not Found' Errors During Runtime Activation in SIMATIC PCS 7

In SIMATIC PCS 7 OS Servers running WinCC (such as WinCC V7.2 in PCS 7 V8.0 SP2), the fatal startup error 'Start Screen not found'—where graphics displays are visible in WinCC Explorer but unselectable or missing upon runtime activation—is typically caused by project path discrepancies, corrupted server data packages, broken UNC network share permissions, or desynchronized SIMATIC Security Control configurations. To resolve this error and restore server redundancy, engineers must verify that the start picture (e.g., @screen.pdl or @1024x768.pdl) is correctly defined in WinCC Computer Properties, regenerate and re-import the OS Server data package, execute the SIMATIC Security Control utility to repair Windows firewall and DCOM user group rights, and verify that the active Windows login has administrative permissions in the local 'SIMATIC HMI' group.

Architecture of WinCC OS Server Graphic Runtime Initialization

In a SIMATIC PCS 7 redundant server deployment, OS Servers primarily execute background SCADA functions: tag acquisition from AS controllers, Alarm Logging, Tag Logging, and OPC server interfaces. However, in many facilities, engineers configure OS Servers to run a local Graphics Runtime view (pdlrt.exe) to allow local monitoring in the server room.

When WinCC Runtime is activated on the OS Server, the runtime manager reads the project configuration file (<ProjectName>.mcp), checks the Computer Properties for the assigned Start Screen (typically @screen.pdl generated by the OS Compiler), opens the local GraCS directory, and initializes the base viewport. If this sequence fails, the runtime aborts the graphics interface with the error 'Start Screen not found'.

Root Cause Analysis: Why 'Start Screen Not Found' Occurs

When the Start Picture cannot be located despite being clearly present inside the GraCS directory in WinCC Explorer, the issue stems from one of four core problems:

Incorrect Computer Name Assignment: If the project was copied or renamed, or if the server hostname does not match the 'Computer Name' listed in WinCC Explorer, WinCC fails to bind runtime properties to the physical machine.
UNC Path and Windows Share Disruption: WinCC relies on internal Windows shares (<ProjectName>_PRJ and <ProjectName>_GraCS). If Windows file sharing or network adapter bindings are altered, pdlrt.exe cannot resolve file paths via UNC.
Corrupted Server Data Package: External OPC clients or third-party query tools can overload the WinCC DataManager, corrupting the cached server package (.pck).
SIMATIC Security Control Desynchronization: Windows updates or domain policy rollouts frequently overwrite DCOM permissions and firewall rules, preventing WinCC system processes from accessing graphics files.

Configuring Start Picture Properties in WinCC Explorer

To restore the Start Picture configuration in WinCC Explorer:

Close WinCC Runtime on the affected server (SERV_A).
In WinCC Explorer, open Computer in the project navigation tree.
Right-click the computer object matching the local server hostname and select Properties.
Select the Graphics Runtime tab.
Under Start Picture, click Browse.
Select the primary PCS 7 template picture—typically @screen.pdl (for multi-monitor or standard displays) or @1024x768.pdl.
Ensure that window attributes (e.g., 'Title', 'Maximize', 'Scroll Bars') match project standards.
Under the Startup tab, ensure that Graphics Runtime is selected if local display is required.

Resolving Network Permissions and SIMATIC Security Control Desynchronization

If the Start Picture is selected but runtime still reports 'not found', execute the standard Siemens security remediation procedure:

Run SIMATIC Security Control: Click Start, search for SIMATIC Security Control, right-click and select Run as Administrator. Click Repeat Settings to reapply all required DCOM, registry, and Windows Firewall configurations.
Check Windows User Group Memberships: Open lusrmgr.msc (Local Users and Groups). Verify that the logged-on user account is an explicit member of:
- SIMATIC HMI
- SIMATIC NET
- Administrators
Regenerate Server Package: In WinCC Explorer, right-click Server Data, select Create..., and rebuild the server package to ensure internal references are updated.
Reboot the OS Server: A system restart ensures all repaired DCOM permissions and file shares initialize cleanly.

Comparison of OS Server Graphics Startup Failure Scenarios

The following table compares typical graphics initialization failures on WinCC OS Servers:

Error SymptomRoot CauseGraphics Viewer Status in ExplorerCorrective Action'Start Screen not found'Computer Properties Start Picture blank or broken shareFiles visible and openable in ExplorerSet @screen.pdl in Computer Properties; run Security Control'Computer Name Mismatch'Physical PC hostname differs from project nodeProject refuses to openUpdate Computer Name to match Windows hostnameGray Screen / Infinite HourglassGlobal Script Runtime frozen or blocked scriptPictures open but animations frozenTerminate runaway C-scripts via APIDIAG; check logs'Cannot Connect to Server'Network adapter binding or TCP port 135 blockedClient displays disconnect crossbarsRebind Terminal Bus NIC; check Windows Firewall

Verification

Verify that the WinCC OS Server initializes graphics and recovers full redundancy:
1. Activate WinCC Runtime on the primary OS Server (SERV_A).
2. Confirm that @screen.pdl loads without error dialogs, displaying the standard PCS 7 overview area, button area, and alarm line.
3. Open the WinCC Redundancy status window; verify that both servers (SERV_A and SERV_B) report 'Connected' and that archive synchronization shows 'Fault Free / Synchronized'.
4. Switch an OS Client from SERV_B to SERV_A; verify that process graphics and faceplates update seamlessly without delay.

Limitations and Operational Precautions

While running local Graphics Runtime on an OS Server is convenient for diagnostics, Siemens best practices recommend running OS Servers in 'Server Mode' (without active Graphics Runtime) in high-throughput production plants to reserve all CPU cores and RAM for database logging, alarm processing, and client requests. Never delete the system picture files starting with @ (such as @screen.pdl, @overview.pdl); these files are core system components maintained by the PCS 7 OS Compiler.

Engineer FAQ

What is the standard PCS 7 Start Picture for an OS Server?

In standard PCS 7 installations, the default Start Picture generated by the OS Compiler is @screen.pdl. It serves as the master container hosting the screen navigation hierarchy, alarm banner, and work area.

Why did the external OPC Client lag cause the WinCC Server issue?

Unoptimized or high-frequency OPC queries can exhaust WinCC DataManager thread pools and lock memory-mapped files. If the server is restarted abruptly while files are locked, project database descriptors can become corrupt, causing startup errors.

Can an OS Server operate redundantly without running Graphics Runtime?

Yes. WinCC Redundancy synchronizes Tag Logging and Alarm Logging databases at the service level. Graphics Runtime is purely a local visualization shell; deactivating graphics on the server has zero impact on redundancy synchronization or OS Client connectivity.