Troubleshooting Disappearing Server Names (0.0) and CEMAT Function Failure on WinCC OS Clients

In SIMATIC PCS 7 with CEMAT, if OS clients display '0.0' instead of the server name in the graphic banner following an OS download, the client has failed to resolve the active redundant OS server prefix. CEMAT functions such as 'Objects in group', bypassed interlocks, and simulation lists rely on internal variables (@RM_MASTER_NAME, @LocalMachineName) and the loaded Server Data package (.pdk). When '0.0' appears, the client cannot communicate with the CEMAT runtime server engine. To resolve this: regenerate Server Data on the primary OS server, assign the updated package to the OS client project, verify network name resolution (hosts/lmhosts) and Simatic Shell multicast encryption, and run the CEMAT OS Project Editor.

Executive Summary

In cement plants utilizing PCS 7 V8.1 and the CEMAT Minerals library, redundant OS server pairs provide high-availability visualization to multi-client operator stations. A critical operational failure occurs when, following an OS project download, operator stations display '0.0' in the top-right visualization banner instead of the valid active server name. While basic WinCC picture navigation may partially work, specialized CEMAT functions—including group status overviews, bypassed interlock listings, and simulated signal summaries—completely fail. This article identifies the root cause of the '0.0' unassigned server condition and provides the definitive resolution procedure.

Architecture and Fundamental Mechanics

The CEMAT visualization architecture relies heavily on symbolic server prefixes to aggregate technological objects across multiple automation systems. Rather than querying fixed tag addresses, CEMAT faceplates and global scripts (such as C_DRV_1D, C_GROUP, and CEMAT_GetServerName()) dynamically read the internal WinCC Redundancy tag @RM_MASTER_NAME and the loaded Server Data package (.pdk).

When an OS client initializes runtime, WinCC Redundancy and the Microsoft RPC subsystem establish connections to the active Master server. If @RM_MASTER_NAME evaluates successfully, the client displays the server hostname and routes CEMAT C-script queries to the server's central database.

The display of '0.0' indicates that the server prefix evaluation returned an uninitialized null pointer or fallback dummy string:
1. Server Data package mismatch: The OS client is operating with an obsolete or corrupted .pdk file downloaded while the OS server was offline.
2. Windows network adapter binding order: The client's Terminal Bus network card is not listed first in the Windows network binding priority, causing Simatic Shell RPC broadcasts to bind to a loopback or unrouted interface.
3. Simatic Shell communication failure: Encrypted multicast communication between the OS client and OS server is blocked by firewall rules or mismatched Simatic Shell encryption passphrases.

Step-by-Step Implementation Procedure

Verify Windows Network Binding and Name Resolution:
a. On all OS Clients and OS Servers, open the Windows Network Connections settings.
b. Ensure the network adapter attached to the Terminal Bus has top priority.
c. Open the hosts file (C:\Windows\System32\drivers\etc\hosts) and verify that all OS servers and clients have static, bidirectional IP-to-hostname mappings.
d. Ping each server from the client using the hostname (e.g., ping SERVER_A -4) to verify sub-millisecond response.
Configure Simatic Shell Settings:
a. On the OS client, open Windows Explorer, right-click 'Simatic Shell', and select 'Settings...'.
b. Verify that the correct Terminal Bus network adapter is selected.
c. Verify that 'Multicast settings' match across all stations and that encryption settings (if enabled in PCS 7 V8.1+) share identical passphrases.
Regenerate and Distribute Server Data Packages:
a. On the Engineering Station, open the primary OS Server project in WinCC Explorer.
b. Navigate to 'Server Data', right-click, and select 'Create...'. Verify that the .pdk package generates without errors.
c. Open the OS Client project in SIMATIC Manager, navigate to 'Server Data', select 'Assign...', and ensure the server package is selected.
d. Right-click the OS Client project and execute 'Download' to transfer updated project packages to the client PC.
Execute CEMAT OS Project Editor:
a. On both OS Servers and OS Clients, open WinCC Explorer with runtime deactivated.
b. Open 'OS Project Editor', verify that CEMAT standard screen layouts and scripts are selected, and click 'OK' to reapply CEMAT master templates.
c. Restart WinCC Runtime on the OS Server, verify synchronization, and then launch WinCC Runtime on the OS Client.

Verification

In WinCC Runtime on the OS Client, inspect the top-right corner of the screen: confirm the valid server hostname (e.g., SERVER_A or SERVER_B) is displayed instead of '0.0'.
Open Tag Management or WinCC Channel Diagnosis and verify that @RM_MASTER_NAME contains the active master server name.
Open a CEMAT Group faceplate and execute 'Objects in group': verify all drives, dampers, and sensors populate correctly.
Open the CEMAT bypassed interlock and simulation summary window: verify active signals populate from the AS controllers without communication errors.

Limitations and Operational Precautions

Never download an OS project to an OS Client while an OS Server delta download is in progress, as intermediate package states will corrupt client pointers. In redundant environments, always allow redundant synchronization (@RedundantServerState = 1 and 2) to complete before switching preferred servers. Sizing and procurement of CEMAT license packages should be validated with an authorized Siemens distributor or the Siemens Industry Mall.

Engineer FAQ

Why does '0.0' appear specifically after an OS download?

An OS download performed before server data regeneration distributes stale connection pointers, leaving the client unable to resolve the server prefix.

What does the tag @RM_MASTER_NAME represent?

It is an internal WinCC Redundancy tag that holds the Windows computer name of the current active Master OS Server.

Can Simatic Shell multicast encryption cause the '0.0' server error?

Yes. If an OS client has a mismatched encryption key or blocked multicast port (port 5225/135), it cannot discover the OS server, resulting in unassigned server pointers.

Do CEMAT standard scripts require running the OS Project Editor after updates?

Yes. CEMAT modifies standard WinCC picture templates and scripts; running the OS Project Editor ensures updated CEMAT scripts are properly bound.

Does preferred server configuration impact the '0.0' display?

If the client's preferred server is down and redundancy failover fails due to corrupted server data, the client cannot switch to the standby partner, defaulting to '0.0'.