Resolving PCS 7 V6.0 Client Alarm Filter 'No Connection' Errors

Problem Summary

In PCS 7 V6.0.1.1 multi-station configurations with two OS servers, one Engineering Station (ES), and four OS clients running Windows 2000, alarm messages are visible on the server and ES picture trees but every OS client reports no connection with server in the WinCC Alarm Control message window. As a result, operators on the client cannot filter the message list by plant zone or message class, even though the same PDL files render correctly on the server side. Within the OS Project Editor invoked on the client, several fields, check boxes, and option buttons appear greyed out and cannot be edited, while the identical dialog on the server remains fully editable.

The symptom set is specific to V6.0.x and earlier: WinCC Alarm Logging Runtime on the client opens, but the client cannot subscribe to the server-side tag archive or to the message archive because the OS package was either never imported, imported against the wrong server alias, or assigned with a client license that does not include OS Client RT with package import rights.

Affected Versions and Platforms

PCS 7 V6.0 OS Server/Client Architecture

PCS 7 V6.0 follows a strict client/server topology. The ES holds the master project database (the CFC/SFC engineering data and the WinCC graphics database). Each OS server hosts its own alarm logging runtime and tag logging runtime and is fed by an S7-400 AS via the S7 Protocol Suite channel. OS clients do not connect to the AS directly; they connect to the assigned OS server through the WinCC server data and read the published tags and messages from the server's package.

Each client must receive a compiled package from its preferred server. The package contains the alarm logging segment, the tag logging segment, the text library, the user administrator exports, and the picture tree topology. Without a valid, current package on the client, the WinCC Alarm Control reverts to no connection with server the moment an operator presses a message filter button.

Root Cause Matrix

Prerequisites

• Identical domain or workgroup membership across ES, both OS servers, and all four OS clients. Mixed workgroups (server in WORKGROUP, clients in a Windows 2000 domain) produce RPC authentication faults that surface as "no connection with server".
• Same Windows 2000 user account name and password used for the WinCC service login on every node (the WinCC service account, not the interactive user).
• OS Client Runtime licenses installed and active in Automation License Manager on every OS client.
• The ES project directory is shared read-only (\<ES>\<project>$) and reachable by all OS servers and OS clients.
• WinCC Alarm Logging and Tag Logging segments compiled on the OS server at least once after the most recent CFC / SFC download.
• Network connectivity: TCP port 102 (S7), TCP 135 (DCOM endpoint mapper), and the dynamic DCOM range (1024–65535) open between server and clients.

Step-by-Step Resolution Procedure

Step 1 — Verify OS Project Editor Is Operating Against a Client Computer Type

1. On the ES, open SIMATIC Manager and select the OS client station.
2. Right-click → OS Project Editor → confirm the dialog opens with the Computer target set to the correct client name (not the server).
3. Switch the Target OS Computer field at the top of the editor from the server to each client, in turn, and save.
4. If controls are still grey, the OS Client Runtime license is missing on that node (R3).

Step 2 — Enable Alarm Logging Runtime in the Client Startup List

1. On the OS client, open WinCC Explorer.
2. Right-click Computer → Properties → Startup tab.
3. Enable Alarm Logging Runtime. Optionally enable Graphics Runtime and Tag Logging Runtime if the client also displays trends.
4. Confirm the configured start order: Alarm Logging Runtime must start before Graphics Runtime, otherwise the Alarm Control subscribes before the segment is loaded and the connection attempt fails.

Step 3 — Import the Server Data on the Client

1. On the OS client, open WinCC Explorer.
2. Right-click Server Data → Import.
3. Browse to the server's compiled package, by default:
   \\<OS_SERVER>\<project_name>\OS\<server_name>\Packages\<server_name>_<yyyy-mm-dd>_<hh-mm>.pck
4. Choose the desired Import Type: Complete import with picture tree update for first-time clients; Update only for clients already synchronized.
5. Click Import. The progress bar must reach 100 % and report Import successful. Any Access denied, File not found, or License missing line stops the process.

Step 4 — Set the Preferred Server for the Client

1. Still on the client, open Server Data in WinCC Explorer.
2. Switch to the Preferred Server tab.
3. Select the OS server that owns the zone(s) the operator should monitor.
4. Verify the Server name field matches the Windows computer name exactly (case sensitive in some DCOM versions). Mismatched case is the most common cause of the "no connection with server" popup when the server is otherwise reachable.

Step 5 — Synchronize the User Administrator

1. On the OS server, open WinCC Explorer → User Administrator.
2. Right-click the user group that holds the operator level (typically OperatorLevel1).
   Verify Authorization for area: Authorization 6 — Operation for filter access, and Authorization 5 — Process controlling if the operator needs to acknowledge alarms.
3. Export the user list: File → Export → .udl file in \\<OS_SERVER>\<project>\OS\<server>\UserSvr.
4. On each OS client, open WinCC Explorer → User Administrator → File → Import and select the exported file.
5. Close and re-open WinCC Runtime on the client.

Step 6 — Configure DCOM Defaults on Every Node

1. Run dcomcnfg.exe on the OS server and each OS client.
2. Under Default Properties set:
     • Default Authentication Level = Connect
     • Default Impersonation Level = Identify
3. Under Default Protocols ensure Connection-oriented TCP/IP is listed first.
4. Restart the WinCC services: net stop "SIMATIC WinCC Runtime" && net start "SIMATIC WinCC Runtime".

Step 7 — Validate the Picture Tree Filter on the PDL

1. Open the alarm PDL on the ES in Graphics Designer.
2. Select the WinCC Alarm Control object.
3. In the configuration dialog open the Message Blocks tab and confirm Date, Time, Number, State, Class, Type, Text are visible.
4. Open the Selection tab. For each filter row, verify the Message Class and Plant Section columns reference server-side tag names, not local tags. A common bug is binding the filter to a client-internal tag such as @local::FilterPlant; this compiles, opens the dialog, but cannot evaluate, and the Alarm Control reports "no connection with server".

Verification Procedure

1. On the OS client, launch WinCC Runtime.
2. Trigger a test alarm: from the ES, force a process tag connected to a message class on the primary server (e.g., set a limit-violation flag).
3. Verify the alarm appears in the client message list within two seconds (default acknowledgement / display latency in PCS 7 V6.0).
4. Click the Filter dialog on the client, select a specific plant zone, click OK. The list must refresh without producing the "no connection with server" popup.
5. Switch the client preferred server to the redundant server. The list must continue to show historical and live messages.
6. Open Alarm Logging — Archive Browser on the client and verify short-term archive entries are visible. If only live messages appear, the alarm archive connection to the server-side Tag Logging is broken (R7).

Field-Proven Diagnostics

Quick Connectivity Test

From an OS client command prompt run the following. Successful output confirms DCOM, RPC, and the OPC server tunnel are open:

net view \\\\OS_SERVER_01
ping -n 2 OS_SERVER_01
telnet OS_SERVER_01 102
telnet OS_SERVER_01 135

WinCC Internal Diagnostics

Enable the WinCC channel diagnostics for the OS server's S7 Protocol Suite:

1. WinCC Explorer → Tag Management → right-click the S7 channel → System Parameters → Logging.
2. Set Trace mode = Short and Trace file = C:\Siemens\WinCC\Diagnose\S7_Trace.log.
3. Reproduce the "no connection with server" on the client, then inspect the log on the server for OPC_DA: read failed or connection timeout.

Registry Inspection

Confirm WinCC recognizes the OS Client Runtime license on the node:

reg query "HKLM\SOFTWARE\SIEMENS\AUTSW\WinCC\RT" /v "LicenseState"
reg query "HKLM\SOFTWARE\SIEMENS\AUTSW\WinCC\RT" /v "ProjectPath"

LicenseState must equal 0x01. ProjectPath must point to the client project folder that contains the imported package.

Licensing Pitfalls

Operating-System-Specific Pitfalls (Windows 2000)

• ForceGuest registry. Windows 2000 defaults to ForceGuest = 1 under HKLM\System\CurrentControlSet\Control\Lsa. Set this to 0 on every node, otherwise the WinCC service account is mapped to the Guest profile and the Alarm Control cannot write back acknowledgements.
• DCOM port range. On Windows 2000 the default dynamic port range is 1024–5000. If a corporate firewall only opens 1024–2000, narrow the client/server conversation and break the alarm subscription.
• DEP and ATSvc. Disable Data Execution Prevention on the OS server's WinCC process if service packs introduced it; WinCC V6.0 was not tested with hardware DEP.
• Time skew. Kerberos rejects requests when client/server clocks differ by more than 5 minutes. PCS 7 V6.0 alarms carry a UTC stamp; a 10-minute drift will cause the server to drop the client subscription silently.

Troubleshooting Matrix

Differences from PCS 7 V7.0 and Later

If the project is upgraded in-place to PCS 7 V7.0 or later, the OS Project Editor is replaced by the Plant View in SIMATIC Manager, and the "no connection with server" popup is replaced by the Server not available status indicator inside the WinCC Alarm Control footer. The package import model also changes: V7.0 uses the Server Data — Automatic Update dialog and per-server publication of picture tree segments. The procedures above apply only to V6.0.x; for V7.0+ refer to the current PCS 7 Operator Station manual.

References in Engineering Notes

• Siemens Industry Online Support — portal for PCS 7 V6.0 service packs and KB articles.
• PCS 7 V6.0 OS Configuration Manual (entry ID 23315944) — canonical reference for OS Project Editor usage.
• WinCC V6.0 Information System — Server/Client Configuration — licensing, package import, and DCOM prerequisites.

FAQ