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Diagnosing Missing Process Pictures and Terminal Bus Network Faults in Legacy WinCC OS Clients

Diagnosing Missing Process Pictures and Terminal Bus Network Faults in Legacy WinCC OS Clients

When a newly installed legacy SIMATIC PCS 7 OS Client (such as Windows XP with WinCC V6.1 and SQL Server 2000) prompts for login but fails to render process picture pages, displaying an empty gray background and the diagnostic error 'Iso Ind Ethernet cannot receive time signal', the failure is caused by broken Terminal Bus name resolution and improper SIMATIC Shell network adapter binding. To resolve this, configure the LMHOSTS file on the OS Client with #PRE entries mapping the NetBIOS names and IP addresses of the OS Servers, bind SIMATIC Shell explicitly to the active Terminal Bus network adapter, and assign and update the OS Server Data packages (*.pck) in the OS Client project.

Table of Contents

Executive Summary

During maintenance or disaster recovery of legacy process facilities running SIMATIC PCS 7 V6.1 on Microsoft Windows XP Professional, engineers occasionally reinstall the operating system, SQL Server 2000, and WinCC V6.1 on an OS Client station. Following successful project download from the Engineering Station (ES), the client launches WinCC Runtime, prompts for operator authentication, but then displays an empty gray workspace: Picture Tree navigation buttons and process graphics never appear. Concurrently, the WinCC diagnose log records communication faults such as 'Iso Ind Ethernet cannot receive time signal'. This issue occurs because the client cannot resolve or access the remote OS Server project directory across the Terminal Bus, caused by missing NetBIOS name caching in Windows XP and unassigned server data packages.

Architecture and Fundamental Mechanics

The architecture of distributed WinCC V6.1 client-server visualization depends on multiple legacy networking components:

1. Terminal Bus Name Resolution Mechanics (NetBIOS and LMHOSTS)

In legacy PCS 7 V6.1 environments operating within a Windows XP workgroup:
- Windows networking relies heavily on NetBIOS over TCP/IP (NetBT) for network share discovery.
- When an OS Client launches runtime, it does not hold local graphics files (*.pdl); it reads them remotely across the Windows network share of the OS Server (e.g., \\OS_SERVER_1\WinCC_Project\GraCS\).
- If DNS is absent, Windows XP broadcast name resolution frequently fails. Without a properly configured LMHOSTS file containing #PRE preload tags, the client cannot locate the server machine name, causing picture loading routines to timeout.

2. SIMATIC Shell Network Adapter Binding

WinCC client-server handshakes, Picture Tree synchronization, and time-signal distribution are coordinated by SIMATIC Shell:
- If the workstation has multiple network adapters (or disabled virtual adapters), SIMATIC Shell frequently defaults to the wrong NIC.
- When bound to an inactive adapter, SIMATIC Shell cannot receive multicast heartbeat packets or time signals, logging 'Iso Ind Ethernet cannot receive time signal' and failing to initialize the runtime picture hierarchy.

3. Server Data Package Assignment

The OS Client project must contain valid, compiled Server Data (*.pck) generated from the OS Server. If the package was generated under a different server name or not assigned in WinCC Explorer, the client project cannot map picture hierarchy requests to the server.

Step-by-Step Implementation Procedure

To resolve the missing picture display and network communication errors on the legacy OS Client:

Step 1: Configure LMHOSTS on the OS Client

  1. On the Windows XP OS Client, navigate to:
    C:\WINDOWS\system32\drivers\etc\
  2. Open the file lmhosts with Notepad (if only lmhosts.sam exists, save a copy named lmhosts without any extension).
  3. Add the IP addresses and computer names of all servers, appending #PRE to ensure persistent caching:
    text 192.168.1.10 OS_SERVER_1 #PRE 192.168.1.11 OS_SERVER_2 #PRE 192.168.1.20 ENG_STATION #PRE
  4. Save the file.
  5. Open Command Prompt and execute nbtstat -R to purge and reload the NetBIOS name cache.
  6. Execute ping OS_SERVER_1 to confirm name resolution succeeds.

Step 2: Configure SIMATIC Shell Network Binding

  1. On the OS Client desktop or in Windows Explorer, open My Computer.
  2. Locate SIMATIC Shell.
  3. Right-click SIMATIC Shell and select Settings....
  4. In the network adapter dropdown, select the physical network card physically connected to the Terminal Bus.
  5. Confirm and click OK.
  6. In the SIMATIC Shell window, verify that OS_SERVER_1 and OS_SERVER_2 become visible in the node browser.

Step 3: Regenerate and Assign Server Data Packages

  1. On the Engineering Station (ES), open SIMATIC Manager.
  2. Right-click the OS Server object -> select Server Data -> Generate.
  3. Open the OS Client project in WinCC Explorer on the ES.
  4. In the left navigation pane, right-click Server Data -> Assign....
  5. Ensure the newly generated server package is checked.
  6. Re-download the OS Client project (PLC -> Download -> OS) to the Windows XP client machine.

Step 4: Verify Windows User Rights and Launch Runtime

  1. Ensure the Windows user account on the client belongs to the local SIMATIC HMI and Administrators groups.
  2. Launch WinCC Runtime on the client.

Verification

To confirm that graphics and communication are fully restored:

  1. Runtime Picture Display Test:
    - Log in to WinCC Runtime.
    - Confirm that the Picture Tree navigation bar populates with plant area buttons.
    - Click area buttons; verify that process flow diagrams (*.pdl) render immediately with live tag data.

  2. Diagnostic Log Verification:
    - Inspect C:\Program Files\Siemens\WinCC\Diagnose\WinCC_Sys_01.log.
    - Confirm that communication status to the OS Server reports 'Connected / Established' and the 'cannot receive time signal' warning clears.

Limitations and Operational Precautions

Operational limitations and precautions:

  1. Windows XP and WinCC V6.1 End-of-Life: Windows XP and WinCC V6.1 reached end-of-support over a decade ago. Operating legacy systems exposes facilities to severe cybersecurity risks. System owners should prioritize upgrading to modern supported releases (PCS 7 V9.1).
  2. Workgroup Password Synchronization: In Windows XP workgroups, passwords between ES, OS Server, and Client must match identically; password discrepancies cause silent network share access rejections.
  3. Network Cable Speed Duplex: Ensure legacy network cards are set to fixed speed/duplex (e.g., 100 Mbps Full Duplex) if auto-negotiation fails on modern managed switches.
  4. Commercial Disclaimer: Verify all migration paths, upgrade packages, and legacy spare parts availability with an authorized Siemens distributor or the Siemens Industry Mall.

Engineer FAQ

Why do process pictures fail to appear on the OS Client even though login succeeds?

Login is validated locally, but process graphics reside on the remote OS Server share. If NetBIOS name resolution or SIMATIC Shell binding fails, the client cannot load pictures across the network.

What does 'Iso Ind Ethernet cannot receive time signal' mean?

It indicates that the station is not receiving broadcast time synchronization frames over the network adapter bound to SIMATIC Shell or WinCC TimeSync.

Why is the #PRE tag required in the LMHOSTS file?

The #PRE tag instructs Windows to preload the NetBIOS name and IP mapping into permanent RAM cache during startup, preventing name resolution timeouts.

Where is SIMATIC Shell configured?

Open 'My Computer' in Windows Explorer, right-click 'SIMATIC Shell', and select 'Settings' to bind the active network card.

What user group is mandatory for WinCC runtime operations on Windows XP?

The logged-in Windows user must belong to the local SIMATIC HMI group.

Technical References

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Related Tags

  • WinCC V6.1
  • Windows XP
  • SIMATIC Shell
  • LMHOSTS
  • OS Client Diagnostics
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