Resolving Web Navigator Client Picture Tree Navigation Failures in SIMATIC PCS 7 V8.0 SP2

In SIMATIC PCS 7 V8.0 SP2 (WinCC V7.2 / WebNavigator V7.2), when process screens operate correctly on the Web Server but Web Clients cannot navigate screens through the Picture Tree Manager, the root cause is either un-published WinCC navigation screens or restrictive Internet Explorer ActiveX security configurations. Web Clients cannot display graphic hierarchies unless all process pictures (*.pdl), faceplates, and system navigation templates (@screen.pdl, @overview1.pdl, @navig.pdl) are compiled and published via the Web View Publisher. To resolve this issue, execute the Web View Publisher on the OS Server, configure Internet Explorer Trusted Sites to allow signed ActiveX controls, and assign @screen.pdl as the operator's start screen in User Administrator.

Executive Summary

The SIMATIC WinCC/WebNavigator option in SIMATIC PCS 7 V8.0 SP2 (WinCC V7.2) enables remote operators, process engineers, and plant managers to monitor and control industrial operations over local intranets or corporate networks via web browsers. While the primary Web Server and local OS Clients function flawlessly, commissioning engineers frequently encounter a scenario where connecting via a remote Web Client results in a broken user interface: while the initial screen may load, the Picture Tree navigation bar is unresponsive, navigation buttons fail to switch screens, or graphic sub-areas remain completely blank. This technical article details the client-server publishing pipeline, explains browser security boundaries, and provides verified procedures to restore seamless navigation.

WinCC WebNavigator Architecture: Server Publishing vs Client Rendering

WinCC/WebNavigator differs fundamentally from standard WinCC OS Clients:

Standard OS Clients: Read native binary *.pdl graphic files directly from the OS Server network share and execute local C and VBScript routines natively.
WebNavigator Server: Must convert proprietary WinCC graphics into a web-optimized intermediate format using the Web View Publisher.
Web Client (Internet Explorer): Utilizes Microsoft ActiveX controls (WinCCViewer.cab, BasicProcessControl) hosted inside Internet Explorer to execute scripts and render graphic primitives. If system navigation screens were omitted during web publishing or blocked by browser security, the navigation tree fails.

Root Cause 1: Missing or Incomplete Web View Publishing

The most common cause of broken Picture Tree navigation is partial publishing:

Engineers often publish only user-created process screens (e.g. Boiler_Area.pdl) while omitting PCS 7 system screens.
The PCS 7 Picture Tree navigation bar is governed by standard system screens:
@screen.pdl: Master screen container.
@overview1.pdl: Alarm banner and top overview bar.
@navig.pdl: Picture Tree navigation button bar.
@area_*.pdl: Cascading area selector screens.
If the Web View Publisher was executed without selecting All pictures and referenced scripts, the Web Client cannot load @navig.pdl, rendering the navigation bar disabled.

Root Cause 2: Internet Explorer ActiveX and Security Zone Settings

Because WebNavigator relies on ActiveX technology, strict browser security blocks script execution:

Untrusted Zone: If the Web Server IP or hostname is not added to the Trusted Sites zone, Internet Explorer enforces enhanced security restrictions, blocking script calls between frames.
ActiveX Execution Blocking: Internet Explorer settings must explicitly allow: 'Download signed ActiveX controls', 'Script ActiveX controls marked safe for scripting', and 'Run ActiveX controls and plug-ins'.
Protected Mode: 'Enable Protected Mode' must be disabled for the Trusted Sites zone in Internet Explorer.

Root Cause 3: Web Client User Authorization and Start Screen Configuration

WebNavigator enforces user authentication independent of Windows sessions:

In WinCC User Administrator, each Web Navigator user must have the Web Navigator checkbox enabled.
Start Screen Definition: The user's assigned start screen must be set to @screen.pdl.
If a user is assigned an isolated process graphic (e.g. Plant_Overview.pdl) instead of @screen.pdl, the session starts without the PCS 7 Split Screen Manager shell, completely omitting the Picture Tree navigation bar.

Step-by-Step Procedure to Restore Picture Tree Web Navigation

To resolve Web Client navigation failures and restore full Picture Tree functionality:

Execute Web View Publisher on Web Server:
* In WinCC Explorer on the OS Server, right-click Web Navigator and select Web View Publisher.
* In the wizard, select All pictures and functions.
* Ensure that system screens beginning with @ are included in the publication list.
* Execute publishing and verify that all screens complete without conversion errors.
Verify User Settings in WinCC User Administrator:
* Open User Administrator on the OS Server.
* Select the target operator account.
* Under the Web tab, confirm that the start screen is set to @screen.pdl and language matches server runtime.
Configure Internet Explorer on Web Client:
* Open Internet Explorer (run as Administrator during first connection).
* Navigate to Tools -> Internet Options -> Security.
* Select Trusted Sites, click Sites, and add http://<Web_Server_IP_or_Hostname>.
* Under Security Level for Trusted Sites, click Custom level....
* Set Download signed ActiveX controls to Enable (or Prompt).
* Set Run ActiveX controls and plug-ins to Enable.
* Set Script ActiveX controls marked safe for scripting to Enable.
* Uncheck Enable Protected Mode for Trusted Sites.
Clear Browser Cache and Reconnect:
* Clear browser temporary files and close all browser windows.
* Launch Internet Explorer and log into the WebNavigator portal.

WebNavigator Navigation and Communication Troubleshooting Matrix

The following table provides diagnosis and remediation for Web Client operational faults:

Failure SymptomUnderlying DefectSpecific Setting AffectedRemediation WorkflowPicture Tree buttons missing or disabledNavigation system screens not published@navig.pdl, @screen.pdlRun Web View Publisher; publish All pictures and functionsBrowser displays red 'X' or blank boxActiveX controls blocked by browser securityIE Security -> Trusted SitesEnable signed ActiveX controls; disable Protected ModeWeb session opens without header barUser start screen misconfiguredWinCC User AdministratorSet operator start screen to @screen.pdl'Page cannot be displayed'IIS Web Server service stoppedWorld Wide Web Publishing ServiceStart IIS service and verify port 80/443 in firewallFaceplate opens but data values show '?'Server package not assigned or DCOM faultWinCC Server Data (*.pck)Assign server package and verify user in SIMATIC HMI

Verification

To verify that Picture Tree navigation operates cleanly on Web Clients:

Initial Login Verification: On the remote Web Client PC, connect to the Web Server via Internet Explorer. Log in with operator credentials. Confirm that the master @screen.pdl container loads with the top alarm line and bottom Picture Tree bar.
Hierarchical Navigation Test: Click different area buttons on the Picture Tree navigation bar. Confirm that sub-areas cascade and corresponding process graphics load within 1 to 2 seconds.
Faceplate Interaction: Click a motor or valve block icon. Confirm that the technological faceplate opens in a pop-up window, displays live process values, and accepts operator setpoints.

Preventive Web Client Maintenance and Windows Group Policy Guidelines

To maintain seamless web access across corporate engineering workstations:

Deploy Domain Group Policy (GPO): Centralize Internet Explorer security zone configurations and ActiveX trust policies via Active Directory GPO to prevent individual workstation drift.
Republish After Graphic Changes: Whenever process graphics (*.pdl) or plant hierarchy structures are modified, execute the Web View Publisher to push updates to the web server cache.
Use WebNavigator Diagnostics: Utilize the WinCC WebNavigator diagnostic tool (WebNavDiag.exe) to audit client-side plugin integrity.

Limitations and Operational Precautions

Never expose a WinCC WebNavigator Server directly to the public internet without an encrypted industrial Virtual Private Network (VPN) or reverse proxy firewall. WebNavigator communications must remain strictly confined to secure plant intranets.

When sizing WebNavigator Server licenses (e.g. 1, 3, 10, or 30 concurrent client connections), all software packages must be verified against official Siemens catalogs and confirmed through an authorized Siemens distributor quotation.

Engineer FAQ

Can WebNavigator run on Google Chrome or Microsoft Edge?

Classic WinCC V7.2 WebNavigator relies on ActiveX and requires Internet Explorer (or Edge in IE-Mode with ActiveX enabled).

What happens if I publish graphics while the Web Server is in runtime?

Web View Publisher can run during runtime, but clients actively viewing modified screens must refresh their browser to load new graphics.

Why must the start screen be set to @screen.pdl?

@screen.pdl is the master PCS 7 runtime frame containing the alarm line, working area, and Picture Tree navigation bar.

Does a Web Client consume an OS Client runtime license?

No. Web Clients consume concurrent WebNavigator licenses on the Web Server rather than dedicated OS Client RT PO licenses.

Resolving Web Navigator Client Picture Tree Navigation Failures in SIMATIC PCS 7 V8.0 SP2