Resolving Faceplate Invocation Failures on Newly Commissioned SIMATIC PCS 7 OS Clients

When an operator clicks a process block icon (motor, valve, PID controller, or analog monitor) on a newly commissioned SIMATIC PCS 7 OS Client and no faceplate appears—despite other OS clients operating normally—the root cause is almost invariably that 'Global Script Runtime' is disabled in the OS Client's WinCC Computer Properties Startup configuration. PCS 7 Advanced Process Library (APL) faceplate invocation relies entirely on background C-scripts and VBS scripts (specifically PCS7_OpenInputFaceplate and @OpenFaceplate). If Global Script Runtime is unchecked, WinCC ignores all script-based click events. To resolve this, open the OS Client project in WinCC Explorer, navigate to Computer Properties > Startup tab, check 'Global Script Runtime', ensure the client user belongs to the local 'SIMATIC HMI' Windows group, and restart WinCC Runtime.

Architecture of Faceplate Calling Mechanisms on OS Clients

In a distributed SIMATIC PCS 7 architecture, OS Clients do not host local process databases. Instead, they connect to redundant OS Servers via Server Data packages (.pck). When an operator views a process screen on a client, graphic objects and block icons are rendered locally by the WinCC Graphics Runtime (pdlrt.exe).

When the operator clicks a block icon (e.g., an APL MotL pump icon), the graphic object executes an ANSI-C mouse-click event calling PCS7_OpenInputFaceplate(). This function parses the tag prefix, identifies the block type from the server package, dynamic-links the appropriate view pictures (e.g., @pg_MotL_standard.pdl), and displays the faceplate inside the picture window. Every step of this operation depends on the active execution of the WinCC Global Script C-runtime engine (ccscript.exe).

Root Cause Analysis: Why Faceplates Fail to Open on Single Clients

When five OS Clients display faceplates correctly but a newly added sixth client fails to react when icons are clicked, the issue is local to the new client's configuration:

Deactivated Global Script Runtime: When an OS Client project is manually created or downloaded without standard template inheritance, the Global Script Runtime component in WinCC Startup properties is often left unchecked. Without this service, scripts attached to graphics objects do not execute.
Manual File Copying Fallacy: Engineers often attempt to solve this by manually copying @***.pdl files between machines. This is unnecessary and ineffective: in a multi-client PCS 7 system, standard @ system faceplate pictures reside on the OS Server or in the client's local installation library (Siemens\WinCC\aplib); copying files will not fix a disabled script engine.
Missing Windows Security Group Rights: If the active Windows user on the new OS Client is not added to the local SIMATIC HMI group, the operating system blocks the inter-process COM communication required between pdlrt.exe and ccscript.exe.
Missing or Corrupt Server Packages: If the client has not loaded the OS Server data package, the script cannot resolve the tag prefix or block type.

Configuring Computer Properties and Runtime Startup Applications

To correctly configure the newly added OS Client station:

On the OS Client PC, close WinCC Runtime.
Open the OS Client project in WinCC Explorer.
In the left navigation pane, right-click Computer and select Properties.
In the Computer Properties dialog, select the Startup tab.
Under 'Start sequence of the WinCC Runtime applications', ensure the following checkboxes are selected:
- Global Script Runtime (Mandatory for faceplates, animations, and scripts)
- Graphics Runtime (Mandatory for visualization displays)
- Alarm Logging Runtime (Required for alarm line display)
Click OK to save the configuration.
Ensure that the active Windows login account is an explicit member of the SIMATIC HMI and SIMATIC NET local groups.
Restart the OS Client computer and launch WinCC Runtime.

Verifying Script Engine Health and Diagnostic APILOG Files

If faceplates still fail to open after enabling Global Script Runtime, diagnose the script execution layer:

Launch WinCC APILOG / Diagnostics: Navigate to C:\Program Files (x86)\Siemens\WinCC\diagnostics and open WinCC_Sys_01.log and PassC.log in a text editor.
Inspect for Script Syntax Errors: Search for lines containing ExecuteScript or OpenFaceplate. Look for errors such as Function not found or Tag prefix invalid.
Run APIDIAG: Launch apidiag.exe from the WinCC bin folder. In the diagnostic console, type dump to view currently running script tasks, queue lengths, and any frozen script execution threads.
Verify Server Package Assignment: In WinCC Explorer on the client, expand Server Data; right-click the server package, select Configure, and verify that the package is loaded and assigned as default for alarms.

Comparison of OS Client Startup Configuration Profiles

The following table compares the runtime behavior of an OS Client when various startup components are omitted:

Startup Application StateGraphic Screen DisplayFaceplate Calling (APL)Alarm Line UpdatesProcess Tag UpdatesGraphics + Global Script + Alarms (Standard)NormalFully FunctionalFully FunctionalNormalGraphics Only (Global Script Unchecked)NormalCompletely Broken (No Click Action)Static / No AlarmsNormalGlobal Script Only (Graphics Unchecked)No DisplayN/ABackground OnlyBackground OnlyGraphics + Global Script (No Alarms)NormalFully FunctionalBlank Alarm BannerNormal

Verification

Verify faceplate functionality on the new OS Client:
1. Activate WinCC Runtime on OS Client 6.
2. Navigate to a process graphic containing analog indicators, motor blocks, and control valves.
3. Left-click an analog monitoring block icon (MonAnL); confirm that @pg_MonAnL_standard.pdl immediately opens in the foreground.
4. Left-click a motor block icon (MotL); confirm that the motor faceplate appears and that operator control buttons (Start/Stop/Auto/Manual) are responsive to clicks.
5. Open Windows Task Manager; verify that ccscript.exe, pdlrt.exe, and CCAlarmLogServer.exe are running as active background processes under the current user session.

Limitations and Operational Precautions

Never manually copy .pdl graphic files directly into an OS Client's project directory unless it is a multi-client project with custom local screens. Modifying or overriding @ system faceplates locally on a single client creates operational inconsistencies across the control room, where operators see different faceplate versions depending on the workstation they occupy. Always manage system faceplates centrally on the Engineering Station and download projects using the official PCS 7 OS Loader.

Engineer FAQ

Why did copying @***.pdl files from a working client not fix the problem?

Because the problem was not missing files, but an inactive script engine. Standard @ faceplates are either loaded dynamically from the server package or from the local WinCC installation directory; copying PDLs has zero effect if ccscript.exe is not running.

Can Global Script Runtime be enabled without restarting the PC?

Enabling Global Script Runtime in WinCC Computer Properties takes effect the next time WinCC Runtime is activated. A computer reboot is only strictly required if user group memberships (such as adding the user to SIMATIC HMI) were changed.

Where are standard APL faceplate C-scripts located on the OS Client?

Standard C-scripts for APL faceplates reside in the global WinCC script library folder at C:\Program Files (x86)\Siemens\WinCC\aplib\FaceplateDesigner and aplib\PCS7.