Troubleshooting Empty APL Block Icons and Missing Alarm Texts on PCS 7 Web Navigator

In SIMATIC PCS 7 WinCC Web Navigator environments, Advanced Process Library (APL) block icons displaying as blank boxes and alarm message tables lacking text strings are caused by missing Web Navigator client plugins, incorrect graphic publishing order, or unassigned Internet Information Services (IIS) MIME types. Resolving this visualization breakdown requires installing the PCS 7 Web Navigator Plugins from the server download page and republishing server data pictures (@pictures) prior to user process mimics.

Architecture of SIMATIC PCS 7 Web Navigator and APL Visualization

SIMATIC PCS 7 Web Navigator provides thin-client process monitoring and control over intranet or internet networks using Microsoft Internet Explorer or the WinCC WebViewer application:
* The Web Server: Hosts the WinCC runtime project, converts PDL graphics to web-compatible XML/compressed formats, and manages client communication via Microsoft Internet Information Services (IIS).
* The Web Client: Downloads ActiveX controls, OCX components, and script engines from the Web Server to render process graphics locally.
* APL Controls: Unlike simple static shapes, PCS 7 Advanced Process Library (APL) block icons and faceplates rely on specialized ActiveX controls (such as Siemens.Simatic.ProcessControl.Faceplates and custom OCX libraries) to display dynamic status symbols, interlock flags, and internationalized alarm text strings.

Root Causes: Missing Client Plugins vs. Publication Incomplete

When a Web Navigator client renders user-drawn static graphics correctly but displays APL block icons as empty frames and alarm controls with blank text rows:
1. Missing Web Navigator Plugins on Client: The client machine has not installed the dedicated PCS 7 APL Web Plugins. Without these local ActiveX controls, the browser cannot interpret APL object models.
2. Incorrect Picture Publishing Order: When publishing the WinCC project via the Web Publishing Wizard, the system pictures (@*.pdl, @overview.pdl, @alarm.pdl) and server data were omitted or published after the process graphics.
3. IIS MIME Type or Security Restrictions: Microsoft IIS blocks downloading necessary file extensions (.ocx, .pdl, .xml) due to missing MIME type declarations or Windows User Account Control (UAC) restrictions.

Correct Web Publishing Sequence for Server Data and Graphics

Publishing a PCS 7 Web Navigator project requires a mandatory two-stage sequence in the Web Publishing Wizard:
1. On the WinCC Web Server, open WinCC Explorer and launch Web Navigator -> Web Publishing Wizard.
2. Stage 1 (Server Data and System Pictures):
* Select Publish Pictures and select all system files starting with @ (specifically @pg_*.pdl, @pcs7_*.pdl, and @screen.pdl).
* Select Publish Functions to publish all project and standard C-scripts and VBScripts.
* Complete the wizard. This generates the core visualization baseline.
3. Stage 2 (User Process Mimics):
* Relaunch the Web Publishing Wizard.
* Select your plant process mimics and graphics.
* Ensure the option Publish referenced pictures is enabled.
* Finish the wizard to generate compressed web assets in the Web Navigator web directory.

Installing PCS 7 Web Navigator Client Plugins and IIS Configuration

To ensure client PCs receive the necessary APL rendering engines:
1. Access Web Server Download Page:
* On the client PC, open Internet Explorer (or WinCC WebViewer) and navigate to http://<Web_Server_IP>/WebNavigator/.
* Log in with authorized Windows/WinCC credentials.
2. Download and Install Plugins:
* In the left-hand navigation pane, click Download Plugin (or Install Plugins).
* Locate the PCS 7 Web Navigator Plugins and APL Block Icons packages.
* Download and run the setup files with administrative privileges.
3. Configure Browser Security:
* In Internet Options, add the Web Server IP/hostname to the Trusted Sites zone.
* Under Custom Level for Trusted Sites, set Download signed ActiveX controls to Enable (or Prompt).
* Disable the Internet Explorer Pop-up Blocker for the Web Server URL.
4. IIS Configuration Check: On the Web Server, ensure the SimaticHMI user group has Read and Execute rights to the WebNavigator directory.

Verification

Launch the Web Navigator client session from the remote computer.
Open an operating process display containing APL motors, valves, and analog transmitters.
Verify that block icons render complete graphical symbols (pump impellers, valve bodies, bar graphs) and live numerical values.
Open the alarm banner or alarm page: verify that alarm timestamps, tag names, and message texts populate cleanly.
Click an APL block icon: verify that the APL faceplate opens smoothly in a pop-up window without ActiveX script warnings.

Limitations and Operational Precautions

Standard web browsers (such as Microsoft Edge or Google Chrome) require Edge IE Mode or the standalone WinCC WebViewer application to support ActiveX-based APL controls.
Installing client plugins requires local Windows administrator rights on the remote client machine.
Every time a PCS 7 service pack or APL library update is installed on the Web Server, client machines must re-download and install updated client plugins.

Engineer FAQ

Why do custom user graphics display properly while APL block icons remain blank?
User-drawn standard shapes rely on basic Windows drawing primitives, whereas APL icons require specialized Siemens ActiveX plugins.
Where are the installation files for Web Navigator client plugins stored on the server?
They are located in the web publishing directory, typically under C:/Program Files (x86)/Siemens/WinCC/WebNavigator/Server/Web/Install/.
Can WinCC Web Navigator run on modern Windows 11 client PCs?
Yes, using the WinCC WebViewer client application or Microsoft Edge in Internet Explorer Compatibility Mode.
Does a Web Navigator client require a dedicated PCS 7 runtime license?
Web clients utilize shared concurrent client licenses hosted on the Web Server (e.g., WinCC Web Navigator 3-client, 10-client license); no local license is required on the client PC.
Why is text missing from the WinCC alarm table on the Web Client?
Missing alarm text indicates that the language text library files or @alarm.pdl system screens were not published during web compilation.
What user group must the web operator account belong to in Windows?
The Windows account must be a member of the SIMATIC HMI and SIMATIC HMI Viewer local security groups on the Web Server.
How do I force Web Navigator to republish all graphics from scratch?
In the Web Publishing Wizard, check the box Publish all pictures completely instead of changes-only mode.
Does Web Navigator support multi-monitor client workstations?
Yes, multi-monitor layouts are supported when configured via WinCC OS Project Editor and launched through the WebViewer desktop application.
What should be done if ActiveX controls fail to register during plugin installation?
Run Command Prompt as Administrator and manually register the failed OCX components using regsvr32 <filename>.ocx.
Can APL faceplates be operated with the same security levels as a standard OS client?
Yes, user authorizations configured in WinCC User Administrator apply identically across standard OS clients and Web Navigator sessions.

Technical References

SIMATIC Process Control System PCS 7 Web Option for OS Manual (V9.0 / V9.1)
SIMATIC HMI WinCC Web Navigator Operating Instructions
Siemens Industry Online Support Entry: Web Navigator APL Plugin Configuration (Entry ID 298515)
SIMATIC PCS 7 Advanced Process Library (APL) Function Manual

Related Tags

PCS 7, WinCC, Web Navigator, APL, Block Icons, Plugins, ActiveX, IIS, Faceplates, Remote Client

Troubleshooting Empty APL Block Icons and Missing Alarm Texts on PCS 7 Web Navigator