Synchronizing Trend Groups Across OS Clients and Servers in SIMATIC PCS 7

Displaying identical runtime trend groups simultaneously across all OS Clients and an OS Server in SIMATIC PCS 7 requires understanding how WinCC scopes .trg trend configuration files stored in the project's TRG directory. By architectural design, trend groups created online at an OS Server have local server scope and are not broadcast to OS Clients, while trend groups created at an OS Client are stored with client scope and made available across all connected OS Clients referencing the server package. To achieve universal trend availability across both server and client monitors, engineers must embed standardized WinCC Trend Controls within shared process pictures (.pdl) or distribute standardized .trg definitions across both scopes using controlled engineering workflows.

WinCC Trend Group Storage Architecture and TRG Scoping

In SIMATIC PCS 7 OS (WinCC), operators and engineers can create ad-hoc trend groups during runtime to compare multiple process values, archive curves, and setpoints. When a user saves an online trend configuration, WinCC creates a formatted configuration file with the extension .trg inside the project's TRG\ directory.

A frequent source of operational confusion is that a trend group saved directly on an OS Server runtime screen does not appear in the trend selection dialog on OS Clients, and vice versa. Inside each .trg file header, WinCC encodes an internal location property:

[Location] = {1}: Scoped specifically to local OS Server runtime sessions.
[Location] = {2}: Scoped specifically to multi-client runtime sessions referencing the loaded server data package.

Manually editing this parameter or toggling between {1} and {2} simply swaps visibility between server-only and client-only modes, but does not achieve simultaneous visibility across both environments.

Architectural Role of OS Servers vs OS Clients

The isolation between server and client trend groups reflects the architectural separation of roles established in the SIMATIC PCS 7 Operator Station system manual:

Station TypePrimary System RoleMaximum Recommended ClientsTrend Group ScopeOperating RecommendationOS Server (Dedicated)Process communication, Tag Logging, Alarm LoggingUp to 64 OS Clients per server pairServer local ([Location] = {1})Headless operation; operators should not monitor directly on serverOS Single StationCombined Server and Operator StationUp to 4 OS ClientsLocal single station scopeSupported only in small plants due to CPU and graphics loadOS ClientDedicated operator control and monitoringConnects to multiple OS ServersMulti-Client shared ([Location] = {2})Standard operator console; trend groups shared across all clients

According to Siemens system guidelines (PCS 7 OS System Manual Chapter 3), an OS Server should only run active operator control and monitoring graphics if a maximum of four OS clients access the server. In medium to large plants, the OS Server runtime should run headless, and operators should exclusively interact via OS Clients.

Methods to Standardize Trend Views Across All Stations

To provide unified trend visualizations accessible to both control room clients and engineering/server stations, engineering teams can implement two proven architectures:

Picture-Embedded WinCC Trend Controls (Recommended): Rather than relying on runtime .trg files, configure pre-defined WinCC Online Trend Controls directly inside process pictures (.pdl). Because process pictures are compiled into the OS project and distributed via OS Client packages, every client and server displays identical, pre-engineered trend curves.
Client-Centric TRG Authoring: Instruct operators to author runtime trend groups exclusively from an OS Client station. When saved from any OS Client, the trend group is written back to the OS Server's TRG\ folder with client scope ([Location] = {2}). All other OS Clients that load that server package can immediately open, view, and modify that trend group.
Automated Dual-Scope Synchronization Script: For small installations where an OS Server acts as a combined single station alongside clients, a scheduled script can duplicate .trg files in the TRG\ folder, maintaining one version with {1} for server runtime and an identical copy with {2} for connected clients.

Procedure for Deploying Pre-Configured Picture Trends

To engineer permanent, globally synchronized trend views:
1. Open WinCC Explorer on the Engineering Station.
2. In Graphics Designer, open or create a dedicated trend picture (e.g., Trends_Boiler_Area.pdl).
3. From the Object Palette, select Controls -> WinCC Online Trend Control and drag it onto the canvas.
4. Open the control properties; configure trend curves by linking directly to Tag Logging archive tags (e.g., FIC101/PV.Value#Archive or TIC102/PV.Value#Archive).
5. Save the graphic and add it to the Plant Hierarchy navigation tree.
6. Run Compile OS and download the server project and client packages.
7. The trend picture is now accessible identically across all OS Clients and the OS Server.

Verification

To verify trend synchronization across stations:
1. On an OS Client, open the trend view and save a new trend group named Shift_Audit_T1.
2. On a second OS Client, open the Trend Selection dialog and confirm that Shift_Audit_T1 appears immediately in the available list.
3. On the OS Server, verify that Shift_Audit_T1.trg is present in <OS_Project_Path>\TRG\.
4. Open the pre-configured process picture trend (.pdl) on both an OS Client and OS Server; confirm that archive curves, ruler cursors, and time ranges display identical process data.

Limitations and Operational Precautions

Never manually edit the internal syntax of .trg files while WinCC Runtime is active. Corrupted trend group files can cause the WinCC Split Screen Manager or trend selection dialog to crash. Furthermore, avoid running complex, high-frequency trend queries directly on a heavily loaded redundant OS Server, as intensive SQL tag logging queries can impact real-time AS-OS communication performance.

Engineer FAQ

Can a trend group created on an OS Client be viewed by other OS Clients?

Yes. When an OS Client saves a trend group, it writes the .trg file to the OS Server's TRG directory with multi-client scope. All other clients connected to that server package can view it.

Why did Siemens separate server and client trend group scopes?

Because in standard industrial architecture, OS Servers are server-class database and communication engines that should not be used as operator consoles. Client trends are separated to support user-specific workstation personalization.

How many OS Clients can connect to a single OS Server?

A dedicated PCS 7 OS Server can support up to 64 OS Clients. However, if the OS Server is also used as an operator station (Single Station), it should support a maximum of 4 clients.