Resolving PCS 7 WinCC Online Trend Control White Box Display

Problem Overview

After upgrading SIMATIC PCS 7 V6.1 from SP1 to SP4, the WinCC Online Trend Control on Operator Station (OS) clients stops rendering trend curves and shows only an empty white box where the trend area should appear. The trend objects compile without errors, the tag connections are valid, and the runtime project loads successfully on both the OS server and the OS clients — yet the trend window is blank, contains no axes, no time scale, and no measured value curves.

The root symptom is visual only: the WinCC picture switches, button actuation, message display, and archive acquisition continue to function normally. Only the Online Trend Control object itself fails to populate its display window. Recreating the trend picture from scratch does not resolve the issue, and incremental or full OS compiles do not clear the fault. The fault is reproduced on multiple client stations, pointing to a server-side configuration drift between the pre-upgrade SP1 baseline and the post-upgrade SP4 deployment.

Affected Versions and Environment

Root Cause Analysis

WinCC Online Trend Control renders curves based on two coupled data sources: the trend configuration (axes, time range, line color, value source) stored inside the OS picture, and the runtime server data generated by the OS compile/download sequence. In PCS 7 V6.1 SP4, the trend parameters for tags planned in PCS 7 are applied as Online Trend Control properties from the master data library at OS compile time. The mechanism is documented in the Siemens support entry How to apply the configuration of trend parameters from PCS 7 (109760739).

When a project is upgraded from SP1 to SP4, three distinct drift conditions can leave the client trend window blank:

1. Stale server data. The OS project on disk still contains SP1-era runtime files. The picture-level trend objects were migrated in the ES, but the generated runtime databases (configuration files, archive mapping) on the OS server were never refreshed, so the client receives a picture that points at archived tags whose runtime metadata does not match the new control version.
2. Mismatched GENERAL tab settings between OS servers. In a redundant OS server pair (OS Server 1 / OS Server 2), the GENERAL tab settings on the Online Trend Control differ between the two servers after upgrade. Only one server's picture contains the fully-applied trend parameter block; the partner server holds a partial configuration that resolves to an empty control. The first time the operator opens the trend, the white-box symptom is reported on whichever server hosts the session.
3. Trend parameter inheritance not refreshed. PCS 7 applies trend parameters (sampling rate, archive selection, time base) from the CFC/SFC chart I/O to the WinCC Online Trend Control during the OS compile. If the compile was performed with "Changes only" and the relevant chart blocks were not marked dirty, the trend property block in the picture is not regenerated, leaving the SP1-era property values in place.

Diagnostic Procedure

Perform the checks below in sequence. Each check confirms or eliminates one root-cause candidate.

1. Compare GENERAL tab settings on both OS servers. Open the affected picture in Graphics Designer on the ES, connect to each OS server in turn via "OS Project Editor → Assign OS Server", and dump the Online Trend Control properties. Look for empty trend name fields, missing time base, or undefined archive selection on one server but not the other.
2. Inspect the WinCC diagnostic files. On the OS server, open <OS_Project>\<Server>\<Project>.log and the WinCC alarm logging AlarmLog.txt. Search for entries referencing the trend control's CCAxTrendControl ActiveX, missing archive segments, or property binding failures.
3. Verify archive configuration. In WinCC Explorer on the OS server, open Tag Logging and confirm that the tags referenced by the trend control are mapped to a process value archive and that the archive is enabled for runtime. A white box with no error message typically indicates the tag resolves but the archive query returns an empty result set.
4. Check the trend parameter block. In the ES, right-click the Online Trend Control → Properties → Trend. Confirm that every configured trend has a populated Tag Name (or Archive Tag) field, a valid Time Range, and a defined Source (online tag, archive tag, or user archive).
5. Review OS compile log. Open the ES and run OS → Compile OS with full compile. Inspect the resulting OS_Compile.log for warnings about unresolved tag references or dropped trend bindings.

Resolution: Regenerate Server Data and Re-Download the OS

The primary corrective action recommended by Siemens support for this class of fault is to regenerate the OS server data and perform a full OS download. This step rewrites every runtime file on the OS server from the ES master, including the trend property blocks, archive bindings, and picture binaries.

Step-by-Step Procedure

1. On the Engineering Station, open SIMATIC Manager and select the OS project in the component view.
2. Right-click the OS and choose OS → Compile OS. Select Entire OS (not "Changes only"). Wait for the compile to complete without errors.
3. Open the OS Project Editor (Start → SIMATIC → PCS 7 → OS Project Editor). Verify that all operator stations (OS Servers, OS Clients, OS Single Stations) are listed and assigned to the correct computer names.
4. On each OS server, stop the WinCC Runtime (right-click the WinCC Explorer tray icon → Stop Runtime).
5. On the ES, right-click the OS and choose OS → Download. Select Entire OS in the download dialog. Confirm when prompted that the download will overwrite the OS server's runtime project.
6. Repeat the full download for every OS server in the project (OS Server 1, OS Server 2, OS Server N). In a redundant pair, both servers must receive a fresh download — partial downloads leave the partner server with the stale property block.
7. On each OS server, start WinCC Runtime. Verify that the trend picture renders on the local OS first.
8. On each OS client, open the trend picture. The white box should be replaced with the configured axes, time scale, and trend curves.

Resolution: Manual Trend Parameter Re-Application

If the full OS download does not clear the fault — typically because the ES master data library itself still holds the SP1-era trend parameters — the trend properties must be re-applied manually to the picture. The Siemens support article 109760739 describes the parameter mapping that PCS 7 performs between the CFC/SFC chart I/O and the WinCC Online Trend Control properties.

1. Open the affected picture in WinCC Graphics Designer on the ES.
2. Select the Online Trend Control and open Properties → Trend.
3. For each configured trend, re-enter or verify the following parameter block:
   • Tag Name: Must be the full WinCC tag name (e.g., Plant/Unit1/Tag1) or an archive tag reference.
   • Source: Set to Online Tag (live value) or Archive Tag (historical) per the design intent.
   • Time Range: Defines the x-axis span (e.g., 1 h, 30 min). Must be a valid WinCC time literal.
   • Update: Sampling interval. For process trends, typical values are 500 ms to 5 s.
   • Color / Line Style: Per the HMI style guide.
4. Re-link the trend to the PCS 7 chart I/O by selecting Properties → Trend → Apply PCS 7 Trend Parameters. This action re-applies the master data library parameters to the control and is the equivalent of a fresh OS compile for that property block.
5. Save the picture, run a full OS compile, and download to the OS server.

Resolution: Repairing a Redundant OS Server Pair

When the GENERAL tab mismatch between two OS servers is the dominant symptom, treat each server as an independent runtime target. The PCS 7 OS Project Editor assigns picture packages by unit; a unit that was added or modified between SP1 and SP4 may have been assigned to only one server's package list.

1. Open OS Project Editor on the ES.
2. On the Operator Stations tab, verify the package assignments for every unit. Ensure that the unit containing the affected trend picture is assigned to both OS servers.
3. If the unit is missing from one server, add it and recompile.
4. Perform a full download to both servers in sequence.
5. Verify trend rendering on each server by connecting the OS client to each server manually (right-click client tray icon → Server Selection).

Verification Checklist

OS Compile and Download Reference

Trend Parameter Mapping Reference

The table below summarizes how PCS 7 applies trend parameters from the CFC/SFC chart to the WinCC Online Trend Control. Each row must resolve to a populated property in the trend control's property block; an empty value in any field can produce the white-box symptom.

Common Error Scenarios and Mitigations

Preventive Maintenance

1. After every PCS 7 service pack or hotfix application, perform a full OS compile followed by a full OS download on every OS server before placing the system back in service.
2. Maintain a baseline copy of the ES project immediately before any SP upgrade. This allows rapid rollback if the upgrade introduces a trend control regression.
3. Audit the OS Project Editor assignments after every structural change to the plant hierarchy. A unit added to one server's package list but not the other is the most common cause of asymmetric trend faults.
4. Periodically review the OS_Compile.log and WinCC runtime logs for unresolved tag or trend binding warnings. A non-fatal warning logged today becomes a white box on the operator console during the next plant disturbance.
5. Verify archive retention and segment time settings against the trend picture time range. A trend requesting 1 h of data from an archive with a 500 MB segment size will render correctly today but may produce an empty control once the segment rotates.

Cross-Reference: WinCC Unified Trend Control

For projects migrating from PCS 7 V6.1 to a current PCS 7 release (V9.x) or to the WinCC Unified SCADA platform, the trend control object has been re-implemented as a native RT Unified control. The functional equivalent is documented in the TIA Portal WinCC Unified Trend Control reference. New deployments should use the Unified control; legacy PCS 7 V6.1 installations remain on the classic ActiveX Online Trend Control described in this article.