Configuring Fixed Decimal Precision on CEMAT C_MEASUR Trend Windows in PCS 7

In SIMATIC PCS 7 installations utilizing the CEMAT cement automation library (such as CEMAT V8.2), the trend window for the analog measurement block C_MEASUR frequently displays integer-only values or inconsistent decimal digits along the Y-axis. This behavior is governed by the value axis formatting in the underlying WinCC Online Trend Control embedded in the CEMAT faceplate template picture @C_MEASUR_Trend.pdl. To enforce fixed decimal precision (e.g., displaying 819.2 at all times), open @C_MEASUR_Trend.pdl in Graphics Designer, open the WinCC Online Trend Control properties, select the Value Axes tab, and change the Number Format setting from integer (%d) to floating-point with specified decimal places (%.1f or 1 decimal place).

CEMAT C_MEASUR Technological Functionality and Trend Display

The CEMAT industry library is the Siemens standard control system solution tailored for cement manufacturing, mining, and mineral processing facilities. Within CEMAT, the function block C_MEASUR (FB1006) manages analog instrumentation (temperatures, silo levels, kiln pressures, motor currents, vibration sensors).

When an operator clicks the measurement value on a CEMAT overview graphic, the system displays the block icon and offers a direct callup button to open the associated trend curve window. This trend window is powered by the standard WinCC Online Trend Control hosted inside the CEMAT template picture @C_MEASUR_Trend.pdl (or @C_Trend.pdl). The trend control queries archived historical values from the WinCC Tag Logging database.

Root Causes of Integer Y-Axis Rounding in CEMAT Trends

Operators monitoring critical process variables often notice that the Y-axis value scale displays whole integers only (e.g., 819 instead of 819.2), obscuring subtle process variations. This occurs because:

Default Number Formatting String: In factory CEMAT template pictures, the WinCC Online Trend Control value axis property Number format defaults to Auto or standard integer format (%d / 0 decimals) to accommodate wide ranges without label clipping.
Decoupled Archive Precision: WinCC Tag Logging archives floating-point numbers (FLOAT / 32-bit real) with full 7-digit IEEE 754 precision. The truncation occurs purely at the presentation layer in the trend control.
Template-Wide Propagation: Because CEMAT utilizes centralized faceplate templates, modifying the number format inside @C_MEASUR_Trend.pdl automatically applies the decimal precision formatting to every C_MEASUR trend window project-wide.

WinCC Online Trend Control Formatting Syntax Matrix

The following table details formatting syntax for the WinCC Online Trend Control Value Axis:

Format Syntax StringDisplay Output ExampleDecimal BehaviorTypical Engineering Application%d or 0 Decimals819Integer Only (Rounds to nearest whole)Motor speeds (RPM), discrete counts%.1f or 1 Decimal819.2Fixed 1 Decimal PlaceKiln temperatures, draft pressures, flows%.2f or 2 Decimals819.25Fixed 2 Decimal PlacesGas analysis percentages, lab chemistryAutoDynamically shiftsExpands/contracts with zoomGeneral trend overviews%e8.192e+02Scientific Exponential NotationUltra-low concentration analyzers (PPM)

Step-by-Step Procedure to Apply Fixed Decimal Formatting

To configure fixed decimal precision across all CEMAT C_MEASUR trend windows:

Locate and Open the CEMAT Trend Template:
- In WinCC Explorer on the Engineering Station or OS Server, open Graphics Designer.
- Open the picture named @C_MEASUR_Trend.pdl (or @C_Trend.pdl depending on the CEMAT release version).
Open WinCC Online Trend Control Properties:
- Double-click the embedded WinCC Online Trend Control object in the workspace.
- In the configuration dialog, navigate to the Value Axes (Y-Achse) tab.
Configure Number Format:
- Under the Value Axis property group, select the primary Y-axis.
- Locate the parameter Decimal places (or Number format).
- Change the value from 0 to 1 (or enter format string %.1f).
- If ruler / cursor value displays are present, verify that the Ruler / Coordinate Value format is also configured for %.1f.
Save Picture and Distribute to OS Clients:
- Save the picture @C_MEASUR_Trend.pdl.
- If operating in a multi-client or server architecture, ensure the modified PDL is copied to the GraCS directory of all OS Servers and Standby Servers, or downloaded from SIMATIC Manager.

Verification

Verify trend decimal rendering:
1. Open WinCC Runtime on the Operator Station.
2. Click a C_MEASUR block icon or faceplate to open the trend window.
3. Verify that the Y-axis scale markers display formatted decimals: e.g., 818.0, 818.5, 819.0, 819.5.
4. Move the trend ruler cursor over historical curves; confirm that the ruler tooltip displays the measurement with exact decimal precision (e.g., 819.2).
5. Open multiple different measurement trends (e.g., temperature vs pressure) to confirm universal template inheritance.

Limitations and Operational Precautions

Template Overwrites During CEMAT Upgrades: Applying CEMAT service packs or running the OS Project Editor with template replacement enabled may overwrite @C_MEASUR_Trend.pdl. Always maintain project backups of modified templates.
Y-Axis Width Constraints: Increasing decimal places from 1 to 3 expands the horizontal pixel width of axis labels. Ensure sufficient axis margin is configured to avoid truncating leading digits.
High-Frequency Noisy Signals: Displaying multiple decimal places on un-filtered, high-noise measurements (such as draft pressure) can cause distracting visual jitter on trend scales; apply deadbands where appropriate.

Engineer FAQ

Does modifying @C_MEASUR_Trend.pdl require an OS Compile?

No. Graphic templates in GraCS are presentation files. Modifying picture properties does not affect WinCC Tag Management and requires zero OS compilation.

Why did my changes disappear after compiling the OS Project Editor?

If the OS Project Editor is executed with the option 'Update Picture Files' enabled, it restores factory CEMAT PDLs. Deselect this option or restore the customized template afterward.

Can I configure different decimal places for different C_MEASUR blocks?

The template picture sets a global format. To vary decimals per measurement, the number format must be dynamically bound to an internal block attribute (such as DecPlaces) via a C/VBS script.

Does this change apply to standard APL trend controls as well?

Yes, the identical procedure applies to standard APL trend windows hosted in @pg_apl_trend.pdl by modifying the WinCC Online Trend Control properties.