Configuring WinCC 7.4 Graphics Runtime Autostart in Service Mode

Overview

WinCC 7.4 supports two distinct runtime hosting modes: interactive mode, in which a user logs in to Windows and starts the runtime from the WinCC Explorer or the system tray, and service mode, in which the SIMATIC WinCC runtime is launched as a Windows service at machine boot. Service mode is the deployment of choice for operator stations on the plant floor because it does not require a logged-in user and survives logoff/reboot cycles unattended.

A common commissioning question on Windows 7 / Windows Server 2008 R2 stations is: "If the WinCC service is already running, how do I autostart the Graphics Runtime (PdlRt.exe) when an operator logs in, without manually clicking Start Graphics Runtime in the tray icon?" The Siemens Knowledge Base article 23061262 covers WinCC's built-in autostart mechanism, but that mechanism restarts the entire WinCC runtime. When the runtime is already active as a service, that mechanism is a no-op for PdlRt.exe. This reference documents the field-proven procedure to launch PdlRt.exe at user logon while the rest of WinCC is hosted as a service.

Prerequisites

• WinCC 7.4 (Update 1 through Update 14) installed on Windows 7 SP1 / Windows Server 2008 R2 or later; this procedure is also valid for WinCC 7.4 SP1.
• WinCC project with an active runtime license (single-station or client/server).
• WinCC configured in Service Mode via the SIMATIC WinCC Service Mode tool or by registering the service manually. Confirm by opening services.msc and verifying CCStartService (or SIMATIC WinCC Service) is set to Automatic.
• Local Administrator rights on the engineering / operator station.
• A domain or local user account with Log on as batch job privileges if you implement the Scheduled Task method.
• The PdlRt.exe binary located at C:\Program Files (x86)\Siemens\WinCC\bin\PdlRt.exe. Confirm the path on x64 hosts; on 32-bit Windows the path is C:\Program Files\Siemens\WinCC\bin\PdlRt.exe.

WinCC 7.4 Process Architecture

Understanding the runtime topology is critical before touching the autostart configuration. A WinCC 7.4 runtime is not a single process; it is a coordinated set of executables managed by the WinCC Service Manager.

*PdlRt.exe starts with the service only when the WinCC project has Graphics Runtime selected in Computer Properties → Startup AND the service mode tool is configured to honor that flag. In many service-mode deployments PdlRt.exe is intentionally left out so that operators see a clean desktop before the HMI appears.

Why the Standard WinCC Autostart Procedure Fails

The procedure documented in Siemens KB 23061262 registers the entire WinCC runtime as the autostart target. The implementation creates (or modifies) the registry value

with the value

This works correctly when no WinCC runtime is running, because CCStartStop.exe will launch the complete runtime stack including PdlRt.exe. In a service-mode deployment, however, CCStartService.exe is already running and refuses to spawn a duplicate. The launcher short-circuits and the Graphics Runtime is never invoked. The operator still sees a clean Windows desktop with only the WinCC tray icon, and must click Start Graphics Runtime manually. The same logic explains why the WinCC Explorer menu Start Graphics Runtime behaves inconsistently in service mode – it issues a service-control request that may be ignored if the runtime is already considered "active".

Step-by-Step: Configure PdlRt.exe Autostart

1. Verify the WinCC service is running: open services.msc, locate SIMATIC WinCC / CCStartService, and confirm status = Running, startup type = Automatic.
2. Open the WinCC project once in WinCC Explorer and confirm the picture tree compiles without errors. PdlRt.exe reads the compiled PDL cache from the active project directory.
3. Identify the project directory. Typical locations are C:\WinCC\<ProjectName> or D:\Projects\<ProjectName>. Note this path.
4. Determine which startup picture should appear when PdlRt.exe is invoked. Open the project's Computer Properties → Graphics Runtime and record the Start Picture field (e.g. Startup.pdl).
5. Choose one of the autostart mechanisms below and implement only one of them. Implementing multiple methods causes duplicate PdlRt.exe instances.

Method A — Startup Folder Shortcut (Simplest)

This method works when the operator is required to log in interactively (no auto-logon).

1. Log in as the operator.
2. Open %APPDATA%\Microsoft\Windows\Start Menu\Programs\Startup in Windows Explorer.
3. Right-click → New → Shortcut.
4. Enter the target:
   "C:\Program Files (x86)\Siemens\WinCC\bin\PdlRt.exe"
5. Name the shortcut WinCC Graphics Runtime and click Finish.
6. Right-click the new shortcut → Properties → Shortcut tab. In Target, append the project switch if your environment requires it (see Command-Line Reference below). In Run, select Minimized so the console window does not flash on the operator's screen.
7. Log off and log back in to verify.

Method B — Registry Run Value (Most Compatible)

The Run-key approach survives most Group Policy user-configurations and does not depend on the explorer shell.

1. Open regedit as Administrator.
2. Navigate to HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Run.
3. Create a new String Value named PdlRt.
4. Set the value data to:
   "C:\Program Files (x86)\Siemens\WinCC\bin\PdlRt.exe"
5. Close the registry editor and log off / log on to test.

Method C — Scheduled Task (Recommended for Production)

Task Scheduler gives the cleanest control: the trigger fires on user logon, the task can run with highest privileges, and the historical log helps with audits.

1. Open taskschd.msc.
2. Click Create Task (not Create Basic Task).
3. General tab: name = Start WinCC Graphics Runtime. Tick Run whether user is logged on or not only if you have tested the resulting session-0 isolation; otherwise leave it off and tick Run with highest privileges.
4. Triggers tab: New… → At log on → Specific user → select the operator account. Tick Enabled.
5. Actions tab: New… → Start a program → Program/script:
   C:\Program Files (x86)\Siemens\WinCC\bin\PdlRt.exe
6. Conditions tab: untick Start only if on AC power if the station is a panel PC. Untick Start the task only if the computer is on AC power if relevant.
7. Settings tab: tick Allow task to be run on demand; If the task fails, restart every = 1 minute, up to 3 attempts – this recovers gracefully from a transient Explorer crash.
8. Click OK, supply the operator's password if prompted, and log off / log on to verify.

Method D — Group Policy Logon Script

For fleets of operator stations managed centrally, deploy the same trigger through Active Directory:

1. Create a batch file StartPDLRT.bat in \\<domain>\NETLOGON:
   @echo off
"C:\Program Files (x86)\Siemens\WinCC\bin\PdlRt.exe"
2. Open gpmc.msc, edit the GPO linked to the OU containing the operator stations.
3. Navigate to User Configuration → Policies → Windows Settings → Scripts → Logon.
4. Add StartPDLRT.bat as a Logon script.
5. Force a Group Policy refresh on the operator station (gpupdate /force) and log off / log on.

PdlRt.exe Command-Line Reference

Although the WinCC documentation focuses on configuration from WinCC Explorer, PdlRt.exe accepts a small set of command-line switches. The parameters below are documented for WinCC 7.4 in the WinCC Information System under Graphics Runtime → Calling Graphics Runtime from the Command Line.

Verification and Commissioning

1. Reboot the operator station and confirm Windows boots into the WinCC service (no interactive user required).
2. Log in as the operator. Within 10–20 seconds, the configured startup picture should fill the screen.
3. Open Task Manager → Details and confirm one and only one PdlRt.exe entry is listed. Multiple entries indicate that two autostart mechanisms are active.
4. Confirm tag updates are live: from the active picture, toggle a writable tag (e.g. motor start) and verify the change of state propagates.
5. Open the WinCC service log file C:\Program Files (x86)\Siemens\WinCC\diagnose\WinCC_Service_<ComputerName>.log and search for entries around the logon timestamp – they should show no "PdlRt duplicate instance" warnings.
6. Repeat the test after a planned power loss to confirm unattended recovery.

Troubleshooting Matrix

Field-Commissioning Notes

UAC on Windows 7. If the operator account is a standard user (recommended) and User Account Control is enabled, registry changes in HKCU\…\Run do not require elevation. Scheduled tasks that Run with highest privileges do require the operator's password at task creation but execute elevated at logon without prompting.

Session 0 isolation. On Windows Server 2008 R2 / Windows 7 with the default security baseline, scheduled tasks configured Run whether user is logged on or not execute in session 0 and will not display the HMI on the operator's interactive desktop. Always test this configuration with the operator present before declaring the station ready.

Auto-logon and silent reboot. When the operator station auto-logs-on, the Run-key / Scheduled Task mechanism fires after the desktop is built. To hide the brief black desktop background, set the wallpaper to the same .pdl picture rendered by the project, or enable the WinCC Desktop Background integration in Computer Properties → Graphics Runtime.

Redundant pairs. Some sites run two operator panels in parallel for redundancy. Configure each panel with its own Scheduled Task pointing to its own project copy; do not share the same project path across two panels because the CCStartService-level lock file will collide.

Migration to WinCC 8.x or TIA WinCC Professional. The same autostart logic applies; however the binary moves to PdlRt.exe under C:\Program Files\Siemens\Automation\WinCC RT\bin. Adjust all paths accordingly when migrating. For TIA Portal Runtime (WinCC Runtime Professional / Comfort), the equivalent process is RT_Adv.exe or WinCCRTPro.exe and is typically autostarted via AutoStart configuration inside TIA, not via the Windows mechanisms described here.