Displaying Historical PID Trend Curves for Archived Tags in WinCC Faceplates

Displaying historical trend curves for PID parameters (PV_In, SP, LMN) upon opening a WinCC faceplate requires configuring cyclic tag archiving within SIMATIC PCS 7 Tag Logging. By default, faceplate trend views display only real-time online buffer values that accumulate while the faceplate remains open and reset upon closing. To view historical curves, select the controller block parameters in Continuous Function Chart (CFC), enable the 'Archive' attribute with an appropriate sampling cycle, and perform an OS Compilation with Archive Tags selected. When the faceplate opens in runtime, WinCC OnlineTrendControl automatically queries the historical archive database, rendering continuous historical performance curves.

Online Real-Time Trends vs Historical Archive Trends

When an operator opens a standard PID controller faceplate (e.g., @PG_PIDConL_Trend.pdl or @PG_CTRL_PID_Trend.pdl), the integrated WinCC OnlineTrendControl can operate in two distinct modes:

Online Tag Mode (Temporary): The control plots values sampled directly from the AS controller in real time. Historical data prior to opening the faceplate is completely blank, and all plotted data is discarded when the window closes.
Archive Tag Mode (Historical): The control links to historical archives maintained by the WinCC Tag Logging subsystem. Upon opening, the trend instantly queries circular SQL database segments, displaying minutes, hours, or days of historical tuning behavior.

Configuring CFC Block Parameter Archiving

To enable historical trend logging directly from the engineering system:

Open the target Continuous Function Chart (CFC) hosting the PID controller (PIDConL or CTRL_PID).
Right-click the block parameter (e.g., PV_Out.Value, SP.Value, or MV.Value / LMN.Value) -> select Object Properties.
In the parameter properties dialog, navigate to the Archive dropdown:
- Select Archiving (or Long-term archiving).
- Configure the acquisition cycle (e.g., 1 s for fast loops or 5 s for slow temperature loops).
Repeat for all three core PID variables (PV, SP, LMN).
Save the chart and close CFC.
In SIMATIC Manager, initiate an OS Compilation (Changes Only), ensuring the checkbox for Archive Tags is checked.

WinCC Tag Logging Integration Matrix

The following table specifies archiving settings for PID controller variables:

PID ParameterTypical CFC PinArchive Tag Name FormatAcquisition CycleArchive TypeProcess ValuePV_Out.Value (or PV_In)<ChartName>/<BlockName>#PV_Out.Value1 second / CyclicTag Logging Fast / SlowSetpointSP.Value<ChartName>/<BlockName>#SP.Value1 second / CyclicTag Logging Fast / SlowManipulated OutputMV.Value (or LMN)<ChartName>/<BlockName>#MV.Value1 second / CyclicTag Logging Fast / Slow

Verification

To verify historical trend operation in WinCC Runtime:

In WinCC Explorer, open Tag Logging and verify that archive tags exist for PV, SP, and LMN under the Process Value Archive.
Activate WinCC OS Runtime and navigate to the process graphic containing the PID block icon.
Click the block icon to open the PID faceplate, then click the Trend View icon.
Confirm that historical curves immediately populate across the trend axis showing preceding process behavior.
Use the trend ruler tool to inspect past timestamps and verify continuous data acquisition without gaps.

Limitations and Operational Precautions

Operational boundaries for faceplate trend archiving:

Fast Archive Buffer Sizing: High-frequency archiving (1-second intervals on thousands of tags) rapidly fills the Tag Logging Fast buffer. Ensure circular archive disk allocations match plant retention requirements.
OS Compile Overwrite: Never manually configure faceplate archive tags directly in WinCC Tag Logging editor if the project uses PCS 7 OS Compilation. Manual entries will be overwritten or orphaned during subsequent OS compiles.
Tag Logging Licensing: Each archived analog variable consumes an archive tag license count. Verify available WinCC Archive Tag license capacity via Automation License Manager.

Engineer FAQ

Why is the trend window blank when I first open a PID faceplate?

If the PID parameters are not marked for Archiving in CFC, the trend control operates in online buffer mode, which only starts plotting data from the exact moment the faceplate opens.

How do I change the time range displayed in the faceplate trend window?

In the APL trend view, click the time range dropdown or configuration button on the WinCC OnlineTrendControl toolbar to select time spans (e.g., 10 minutes, 1 hour, 8 hours).

Can User Archives be used instead of Tag Logging for PID curves?

While User Archives can store tabular batch records, standard WinCC faceplate trend controls are tightly coupled to Tag Logging process value archives for graphical curve rendering.

Do archive tags consume WinCC runtime licenses?

Yes. WinCC packages include a base number of archive tags (typically 512). Archiving additional process variables requires WinCC Archive Tag license upgrades.