Persisting and Reverting OnlineTrendControl Properties in SIMATIC PCS 7 v8.1 WinCC OS

In SIMATIC PCS 7 v8.1 WinCC, runtime modifications made by operators to WinCC OnlineTrendControl (such as curve scaling, trend colors, time axes, and tag assignments) are no longer saved directly into the master graphic picture inside the server GraCS folder as in legacy versions. Instead, runtime trend configurations are stored client-locally in user-specific configuration files or the local WinCC client project directory. To persist operator adjustments permanently, operators must utilize the 'Save configuration' toolbar icon, while engineers can revert to the pristine engineering baseline by deleting the local configuration override or re-exporting the master picture from the Engineering Station.

OnlineTrendControl Architecture and Storage Mechanisms in PCS 7 v8.1

In SIMATIC PCS 7 v8.1, historical and real-time process trending utilizes the WinCC OnlineTrendControl ActiveX control:
* Legacy Behavior (PCS 7 v6.x / v7.0): Clicking 'Save' on a trend control during runtime modified the static .pdl graphic file directly inside the server's GraCS directory. This frequently caused multi-client contention where one operator's zoom level permanently altered the screen for all other operators in the plant.
* Modern Architecture (PCS 7 v8.1 / v8.2 / v9.x): Siemens decoupled runtime operator adaptations from static engineering graphics. Master pictures (*.pdl) remain read-only on the OS Server. Operator-specific trend adjustments are serialized into independent XML/INI configuration streams stored locally per client workstation or Windows user profile.

Client-Side vs Server-Side Trend Configuration Persistence

The storage destination of trend adjustments depends on the configuration mode:
1. Local Client Persistence: When an operator adjusts curve limits and clicks Save configuration (disk icon on the trend toolbar), WinCC saves an XML profile in the client's local user directory:
C:\Users\<User>\AppData\Local\Siemens\WinCC\ or the local project path.
2. Server-Wide Template Persistence: If an automation engineer requires trend adjustments to become the universal default across all OS Clients, the trend must be configured in WinCC Graphics Designer on the Engineering Station (ES) and deployed via an Entire OS Download.
3. Reverting to Engineering Defaults: When a shift change occurs, an operator can click the toolbar button Load original configuration to immediately discard temporary zooms and restore the engineered trend baseline.

Procedure to Persist or Restore Engineering Trend Baselines

Follow this procedure to manage trend configurations in PCS 7 v8.1:

[Phase 1: Configure Master Trend Template on Engineering Station]
   │  • On ES: Open WinCC Graphics Designer -> Open the trend picture (*.pdl)
   │  • Double-click WinCC OnlineTrendControl -> Configure permanent default curves,
   │    axes, colors, and archive tag assignments
   │  • Save picture -> Compile OS and download to target OS Servers
   │
[Phase 2: Enable Operator Toolbar Persistence Functions]
   │  • In WinCC OnlineTrendControl Properties -> "Toolbar" tab:
   │      - Ensure button "Save configuration" (ID 1002) is enabled
   │      - Ensure button "Load configuration" (ID 1003) is enabled
   │      - Ensure button "Restore original configuration" (ID 1004) is enabled
   │
[Phase 3: Clear Corrupted Local Trend Overrides on OS Clients]
   │  • If an OS Client displays a distorted or locked trend:
   │  • Close WinCC Runtime on the client
   │  • Navigate to the client's project directory or user profile
   │  • Delete the local trend configuration file (*.con / *.xml)
   │  • Re-open WinCC Runtime -> The client loads the clean server baseline!

Trend Storage Location and Persistence Behavior Matrix

Compare trend persistence mechanisms across PCS 7 versions:

Architecture / VersionSave Action DestinationImpact on Other ClientsRestoration MethodLegacy PCS 7 (v6.x / v7.0)Server GraCS\*.pdl fileUniversal (Overwrites all screens)Re-download picture from ESPCS 7 v8.1 (Default)Client User Profile / Local XMLIsolated to local workstationToolbar button: 'Restore original'PCS 7 v8.1 (Server GraCS)Read-only during RuntimeNoneServer file remains intactWinCC WebUX / WebNavigatorBrowser Cookie / Web Server CacheIsolated to browser sessionClear browser session cache

Verification

To confirm that trend properties persist and revert accurately:
1. On an OS Client, open the process trend screen in WinCC Runtime.
2. Modify curve scaling (e.g. change Y-axis limits from 0-100 to 20-80); click Save configuration.
3. Close the picture and reopen it; verify that the custom 20-80 scaling is retained.
4. Click the toolbar button Restore original configuration; verify that the trend immediately reverts to the 0-100 engineering baseline.
5. On a neighboring OS Client, open the same trend; confirm that the first client's adjustments did not alter the second client's display.

Limitations and Operational Precautions

Never grant operators direct file system write access to the server GraCS directory across network shares. Overwriting server .pdl files during active runtime can cause graphical rendering lockups and invalidate OS project checksums. Always use standard WinCC OnlineTrendControl toolbar commands for runtime persistence.

Engineer FAQ

Where does WinCC v8.1 save the trend configuration file?

It is saved locally on the client machine under C:\Users\<Username>\AppData\Local\Siemens\WinCC\ or in the client project folder under file extension .con or .xml.

Why did 'Save configuration' not affect other OS Clients?

PCS 7 v8.1 intentionally isolates runtime trend modifications to the local workstation to prevent one operator's display adjustments from disrupting other control room operators.

How do I make a trend modification permanent for all users across the plant?

Open the graphic in WinCC Graphics Designer on the Engineering Station, configure the trend properties in edit mode, save the picture, and perform an OS download to all servers.

What toolbar button restores the factory engineered trend settings?

The 'Load original configuration' button (represented by an open folder with an arrow or default curve icon) resets the display to the baseline .pdl file.