Restore Archived Values in a PCS 7 PID Faceplate Trend

If a PID faceplate trend reports “Tag value invalid or no connection” while the WinCC archive trend itself is available, check that the PID block I/Os are marked for archiving and that the corresponding archive tags were generated in the OS project. Siemens documents that archive-relevant CFC I/Os become WinCC archive tags during OS compilation when archive options are enabled. In the reported case, selecting long-term archiving, compiling CFC and OS, and downloading the updated OS restored the faceplate trend.

Why the General Archive Trend Can Work While the Faceplate Fails

The general WinCC trend can use a separately configured archive tag, while an APL faceplate may expect archive tags generated from the block I/Os. If an I/O is not marked for archiving or the OS was not compiled with archive-tag creation enabled, the faceplate can lack the tag it expects even though other archive data are available.

Mark the Block I/O for Archiving

In CFC, identify the PID block I/O that should appear in the faceplate trend.
Open the I/O properties and select the required archiving mode. In the reported case, “Long-term archiving” was selected.
Save and compile the CFC chart so the project reflects the archive attribute.
In the OS compile workflow, ensure the archive-tags option is selected and the OS property to create/update archive tags is enabled.
Compile the OS from the component view and inspect Tag Logging > Archives > Process Value Archives > System Archives for the generated tag.
Download the updated OS to the target station using the approved project procedure.

Choose the Correct Archiving Mode

The CFC manual distinguishes “No Archiving,” “Archiving” (short-term archive), and “Long-term archiving.” Select the mode that matches the plant's retention and archive design. Long-term archiving is not merely a display setting; it can imply additional archive handling and storage.

Check the Faceplate

Open the PID faceplate's Archives view after the OS update. Confirm the expected archive tag is present, the selected time range contains data, and the trend displays a connected value. If the tag is missing from System Archives, revisit the CFC attribute and OS compile options before troubleshooting the graphics.

Verification

Confirm that the faceplate trend plots the intended PID value over a known time period. Compare it with the corresponding WinCC archive trend and check that new values continue to be archived after the update.

Limitations and Operational Precautions

The source does not identify the PID block type or exact PCS 7 version. The exact archive options and OS compile dialogs vary by release. Archive retention affects storage and performance; use the project's archive design rather than enabling long-term storage indiscriminately.

Engineer FAQ

Mark the intended CFC I/O for archiving, compile the OS with archive-tag generation enabled, verify the generated tag under System Archives, and update the OS. The source reports this resolved the faceplate trend.

Technical References

Siemens, CFC for SIMATIC S7 (V9.0 SP5), §10.10.2 “Configuring archive tags”: https://support.industry.siemens.com/cs/attachments/109782631/s7cfcs7b_en-US.pdf
Siemens, PCS 7 – OS Process Control (V9.1), OS archives and process-value display: https://support.industry.siemens.com/cs/attachments/109794375/ps7osp_b_en-US.pdf