Troubleshooting PCS 7 OS Client 'No Connection to Server Data'

Problem Statement: "No Connection to Server Data"

In a SIMATIC PCS 7 V7.0 SP1 plant with an S7-400H automation system, the typical runtime topology consists of one OS Server, one OS Backup/Mirror Server, an Engineering Station (ES), and several OS Clients. After an OS compile and a server-data download, an OS Client that is started on a live system displays a banner reading "No Connection to Server Data" across the top of the runtime window. The user cannot open any graphics, cannot acknowledge or filter alarms, and cannot open trend or user archives from the assigned OS Server. The exact same project archive, when retrieved on a demo system, runs the same OS Client without the message.

This symptom is almost always caused by one of three root causes:

1. The WinCC server package (.pck) on the OS Server has not been (re)generated with the current project, or the file is missing or older than the project on the ES.
2. The OS Client cannot reach the OS Server via the WinCC terminal bus; either the SIMATIC Shell entry for the server is wrong, or the share used to fetch the package is not accessible to the user running the client runtime.
3. The local Windows security context (workgroup vs. domain, missing SIMATIC HMI user rights, blocked DCOM, or firewall) prevents the client from reading the package from the server's share.

PCS 7 V7.0 SP1 Server Data Architecture

In PCS 7 the WinCC server package is the compressed, runtime-ready image of the configured picture tree, tag list, archive configuration, message configuration, user administration, and global scripts. It is created on the ES during the OS compile step and is then transferred to the OS Server. From there, every OS Client downloads a copy at runtime start so that pictures, archives, and messages can be opened without round-tripping every request back through the server.

The package is a single binary file with the project name as the base name and .pck as the extension, for example Plant_Prj.pck. Its timestamp on the server should advance each time a successful OS compile has been downloaded to the server. If the timestamp does not move, the package has not been regenerated even if the project on the ES has changed.

Where Server Packages (.pck) Are Stored

During normal PCS 7 operation you should observe the following:

If the only .pck file you find is under the OSC (OS Client) folder on the ES, that file is the client-side local package generated when the OS Client project is compiled on the ES — not the server-side package that the live OS Client is trying to download. The package on the OS Server itself is the file that must be regenerated, served, and timestamped.

Root Cause Analysis

Walk through the following hierarchy in order. Stop at the first check that fails and resolve it before moving on:

1. OS Server runtime state. The OS Server service must actually be running on the server computer. From the ES, open WinCC Explorer on the server (via SIMATIC Shell) and confirm Runtime is active. If the OS Server is not in runtime, every client will display "No Connection to Server Data" because the package endpoint is not serving.
2. Package presence and freshness. On the OS Server, confirm the .pck exists under Packages and that its modification time is later than the latest ES edit.
3. Terminal bus reachability (SIMATIC Shell). On the OS Client, open the SIMATIC Shell from the notification area. Every OS Server and OS Client in the project must be visible with a green status indicator. A red indicator means the terminal-bus name resolution or the WinCC channel is broken.
4. Share access. From the OS Client, type \\<OSServerName>\<ProjectName>_Prj in Windows Explorer and verify you can open the Packages folder. If you cannot, you will not be able to download the package either.
5. User context. The Windows account under which the WinCC client runtime is started (typically SIMATIC HMI) must have read access to the server share. On a domain, ensure the account exists on every machine. On a workgroup, recreate identical local accounts with the same password on every node.
6. Network and name resolution. ping <OSServerName> from the client must resolve to the server's terminal-bus IP. Verify IP/subnet and that the server firewall allows SMB (TCP 445) and that no third-party endpoint protection blocks WinCC traffic.

Step-by-Step: Generating Server Data Correctly

Per the Siemens Support entry on server data generation, the package is produced automatically during the OS compile, but it can also be produced on demand from the menu. The recommended sequence on the ES is:

1. Open the PCS 7 project on the ES in SIMATIC Manager and switch to the component view.
2. Select the OS Server object in the tree (e.g., OS1) and open the OS Project Editor.
3. Make a deliberate, cosmetic change (e.g., add and remove a single comment in the picture tree) so the editor marks the project as modified. This guarantees the next compile is non-trivial.
4. Right-click the OS Server → Compile OS. In the dialog, leave Generate server data enabled. This is the path the Siemens KB describes as the automatic flow.
5. If you want to regenerate the package without running a full compile, use the menu path Options → OS → Generate server data. This writes the new .pck into the OS Server project's Packages folder via the terminal bus.
6. Watch the progress dialog. A successful generation reports the timestamp of the new .pck; a failed generation reports an error code (commonly related to DCOM, share access, or the OS Server not being in runtime).
7. On the OS Server, verify with Windows Explorer that D:\Projects\ServerName\ServerComputerName\Packages\<ProjectName>.pck now has the new timestamp.

Step-by-Step: Loading Server Data on the OS Client

The download from the OS Server to the OS Client happens automatically the first time the client runtime is started, provided the server is reachable and the share is readable. The sequence is:

1. On the OS Client, start WinCC Runtime. The startup screen shows the message "Connecting to server data...".
2. WinCC reads the assigned server list (configured on the ES under OS Client → Server Assignment) and connects to the master OS Server over the terminal bus.
3. WinCC compares the local cached .pck (if any) with the server's .pck. If the server's package is newer or missing locally, WinCC copies it to %ALLUSERSPROFILE%\Application Data\Siemens\WinCC\<ServerName>\ on the client.
4. If the copy succeeds, runtime continues and pictures, alarms, and archives become available. If the copy fails, the banner "No Connection to Server Data" stays on screen.

Force a clean re-download by stopping the WinCC client runtime, deleting the local cached package directory on the client, and restarting the runtime. This isolates whether the problem is a stale local cache versus an actual server-side issue.

SIMATIC Shell and Terminal Bus Configuration

The SIMATIC Shell is the diagnostic and configuration tool for the WinCC terminal bus. Open it from the Windows notification area (icon SIMATIC Shell) or from Start → SIMATIC → SIMATIC Shell. Each entry in the list represents a WinCC station that the local machine can reach over the terminal bus.

To assign a Windows computer name to an OS Server or OS Client object in the project:

1. On the ES, in the component view, select the OS Server or OS Client object.
2. Open Object Properties → Computer Name.
3. Enter the exact Windows hostname of the target machine (case-sensitive on some WinCC internal paths). This is the name that the SIMATIC Shell will resolve.
4. Recompile and download the OS.

Windows User Rights, Shares, and Services

Three Windows-level configurations must be correct on every PCS 7 computer:

A common field finding is that the SIMATIC HMI user was created on the OS Server with one password and on the OS Client with another. When the OS Server is started with one credential and the client tries to attach via the share, the authentication fails silently and WinCC reports "No Connection to Server Data". Confirm both sides by signing in interactively as SIMATIC HMI on each machine and browsing to the server share.

Domain vs Workgroup Considerations

Moving PCS 7 computers between a Windows domain and a workgroup changes which authentication authority is consulted for every connection. The two configurations have different requirements:

Network and Diagnostic Verification

The minimum set of checks that should always pass before you conclude a "No Connection to Server Data" problem is environmental:

1. Hostname resolution: from the OS Client, run ping -a <OSServerName> and confirm the response matches the server's terminal-bus IP.
2. SMB reachability: net view \\\\<OSServerName> from the client must list the project share.
3. WinCC channel reachability: in WinCC Explorer on the client, Tools → Channel Diagnosis must show the S7 channel as OK.
4. Server-side listener: on the OS Server, run netstat -an | findstr 445 and confirm TCP/445 is in LISTENING.
5. Firewall: temporarily disable the Windows firewall on the server and the client, repeat the runtime start. If the error disappears, add a precise inbound rule for TCP 445 and the WinCC DCOM ports rather than leaving the firewall off.
6. Time skew: confirm all PCS 7 computers are within 5 minutes of each other. Kerberos in particular fails when client and server clocks diverge.

.pck Timestamp and Recompile Behavior

The "timestamp never changes" complaint is a red flag that the OS compile is producing an empty result. Common causes:

Small Test Project Validation

If the production project refuses to cooperate, build a minimal project on the same computer to validate the OS Server's ability to serve packages at all:

1. On the ES, create a new PCS 7 project with one OS Server object and one OS Client object on the same terminal bus.
2. Add one AS (any CPU type) so the project passes the wizard.
3. Compile the OS, generate server data, start runtime on the OS Server, then start runtime on the OS Client.
4. If the test project works, the live project has a project-specific problem (most often a stale WinCC internal path in the picture tree or an archive configuration pointing to a removed drive).
5. If the test project also fails with "No Connection to Server Data", the issue is environmental (shares, SIMATIC HMI user, firewall, terminal-bus adapter) and must be fixed at the Windows/network layer.

Troubleshooting Matrix

Verification Checklist

Before declaring the incident resolved, confirm each line item below:

• OS Server shows Runtime active in WinCC Explorer.
• \...\<Project>_Prj\wincproj\OS\Packages\<Project>.pck on the OS Server has a timestamp that matches the latest ES edit.
• SIMATIC Shell on the OS Client lists the OS Server with a green status.
• OS Client WinCC Runtime starts without "No Connection to Server Data" and opens at least one picture from the picture tree.
• An alarm generated on the AS appears in the OS Client's message line within one polling cycle.
• A restart of the OS Client (with the OS Server still in runtime) re-downloads the package without manual intervention.

FAQ