Retaining Custom Block Icon Changes in PCS7 WinCC OS Compile

Problem Statement

When a SIMATIC PCS 7 engineer modifies properties on automatically generated block icons in a WinCC picture (label text, position, color, SAFE_ID1, SAFE_ID2, custom prefix/suffix fields, hidden diagnostics, or any non-default attribute), the next execution of Create/Update Block Icons during OS compilation resets those properties back to default values. The block icon regenerates from the CFC (Continuous Function Chart) block schema and overwrites the manually tuned HMI element.

This is one of the most common day-2 complaints on PCS 7 sites that follow the @PCS7typicals picture template pattern but need localized visual deviations from a single block instance (for example, renaming a faceplate caption for an operator-facing label, setting a yellow background for an alarm-class override, or wiring SAFE_ID1 for the S7 F-Systems safety block acknowledgement).

The symptom is not a fault code or a WinCC runtime error. It is silent overwrite. Engineers see it only after a routine OS Compile & Download, typically during a plant change management window, when all of the cosmetic or safety property edits vanish.

Root Cause Analysis

The WinCC OS Compile in PCS 7 runs the compiler wizard Create/Update Block Icons against every WinCC picture contained in the OS area referenced by the S7 program. The compiler regenerates block icon instances by reading:

1. The CFC block type definition (chart-in-chart instance or shared block library).
2. The block-icon SymbolLibrary entry shipped in the PCS 7 master data library (@PCS7typicals namespace).
3. The picture's existing block icon instance DB pointer slot referenced through BlockIconType + BlockIconInstance.

If a picture-level option Create/Update Block Icons is set (the default for the first compile), every block icon on that picture is regenerated as a fresh instance from the library source. The PCS 7 OS Compiler does not compare the runtime picture to the source template — it overwrites properties deterministically. Initialization properties such as SAFE_ID1, SAFE_ID2, Label, Tooltip, BackColor, ProcessTagName, custom Dynamic C-action VB-scripts, and any picture-object Property not serialized in the CFC block type are reset to library defaults.

Architectural Constraints

The PCS 7 design assumes one block icon picture + one CFC chart-in-chart block instance pair. The compiler does not natively support partial preservation of a single block icon inside an otherwise auto-generated picture. There are three compiler states for any given picture:

The user's requirement — "I want one picture, dozens of auto-generated icons, and one icon with a single custom property preserved" — is therefore not directly supported in the picture-level toggle. The workaround patterns below bridge that gap.

Solution Method A — Per-Block TYPE Override (Recommended)

This is the cleanest field-proven method and is supported from PCS 7 V8.0 onward (also works on V6 SPx / V7 with manual procedure steps).

Procedure

1. Open the WinCC picture in the Graphics Designer that contains the block icon you need to protect.
2. Select the block icon instance you want to deviate.
3. Open the Object Properties dialog (right-click → Properties, or press Enter on a selected object).
4. Navigate to Properties → Miscellaneous → Block icon TYPE.
5. Change the TYPE field from the library-default value (for example 1 for a CTRL_PID block) to a free user value (for example 100). Each TYPE number is treated by the OS Compiler as a custom instance variant.
6. Save the picture.

Once the TYPE field is set to a non-default value, the OS Compiler's Create/Update Block Icons pass no longer overwrites the instance; it skips it because the icon's TYPE is not in its matching set. The CFC block instance link remains valid (the process tag connection survives), but the picture object keeps every property you set.

Verification

1. Run OS Compile — Complete with Overwrite on the OS server.
2. Activate the WinCC Runtime and open the picture.
3. Confirm the protected icon retains the modified property (label, color, safe ID, etc.).
4. Confirm any newly added CFC blocks still appear (the compile is still adding to the picture).

Solution Method B — Picture Attribute "Do Not Modify"

If the entire WinCC picture must be locked (e.g., a fully hand-tuned overview panel with no auto-generation), use the picture-level attribute in the technical hierarchy of PCS 7 ES.

1. In SIMATIC Manager / PCS 7 Engineering Station, expand S7 Program → OS → Pictures in the component view.
2. Right-click the target picture and choose Object Properties.
3. On the Block Icons tab, clear the checkbox Create/update block icons.
4. Click OK and save the project.

This sets the picture-level flag that the OS Compiler reads during the block icon regeneration pass. The compiler will skip the picture entirely. Use this when you need absolute protection of an entire picture and you accept that new CFC blocks will not auto-generate icons there.

Solution Method C — Disabling the Wizard Globally for the Compile Pass

For PCS 7 V6 / V7 systems where the dynamic wizard Connect faceplate to process tag was historically used, the same end result is achieved by:

1. First compile the OS to generate all block icons.
2. Apply your manual property edits in the Graphics Designer.
3. For every subsequent OS Compile, open the OS Compile dialog and uncheck Create/update block icons before clicking Compile.
4. Manually re-apply only the icons for newly added CFC blocks.

This is operationally tedious for plants with frequent CFC changes but it is the only fully supported path on legacy V6 systems where TYPE override behavior differs across service packs.

Solution Method D — Post-Compile Editing with Process Tag Reconnection

If the engineer already lost properties and must restore the icon to its previous tuned state without a fresh OS Compile, follow this recovery procedure.

1. Open Graphics Designer with the picture open.
2. Delete the regenerated (default-property) block icon.
3. From the @PCS7typicals library, drag the master block icon onto the canvas at the saved X/Y position.
4. Wire the icon to the CFC instance again via Libraries → PCS 7 → Dynamic Wizard → Connect faceplate to process tag (V5.x) or via the manual Dynamic dialog (V6+) where the C-script SetTagMultiStateWait handles the link.
5. Re-apply custom properties.
6. Set TYPE to a non-default value (Method A) so future compiles preserve them.

Property Protection Matrix

Pictorial Workflow

Version-Specific Notes

Always confirm the exact behavior on the actual installed Service Pack. The TYPE field semantics changed between V6.0 and V7.0; the pattern remains valid but specific values that act as "non-default" differ. A safe choice across all versions is any integer value that is not in the library's internal TYPE table (a value such as 9001 for a CTRL_PID icon is conventionally unused).

Troubleshooting Matrix

Operational Checklist

1. Before any OS Compile, snapshot the WinCC picture with custom edits (file copy of *.PDL from the WinCC project folder).
2. Document each protected icon's Type value in the project's engineering log so operators and other engineers know it is intentional.
3. Never delete a protected icon during an OS Compile — the compiler will recreate it as a default and TYPE override is lost.
4. Verify the change in WinCC Runtime, not just in Graphics Designer; some dynamic attributes only render in runtime.
5. For S7 F-Systems blocks (F-CPU, F-DI/DO), confirm that SAFE_ID1 / SAFE_ID2 attributes are still wired correctly after the compile; safety-related HMI displays have audit-trail implications.

Related WinCC Explorer Settings

The OS Compile dialog is reachable in SIMATIC Manager via OS → Compile → Complete (with Overwrite). The dialog includes per-OS settings that affect the icon regeneration pass:

• Computer name mapping — controls which ES objects generate icons on which OS pair.
• Time stamp handling — forces a full or incremental compile.
• Block icon generation scope — controlled per picture object property or per Picture node in component view.

For larger plants, integrating the TYPE-override list into a project-specific engineering guideline (stored in the project documentation folder or in @PCS7typicals as a readme PDF) avoids the situation where a junior engineer unprotects an icon because they thought a non-default property meant a fault.

When to Escalate

If Method A fails on a specific icon type — for example, custom user block types (UserBlock family) developed in the customer library — escalate to Siemens Industry Online Support with a WinCC project export. The TYPE override semantics for custom block types depend on the library vendor's block-icon declaration in the SymbolLibrary; some user block libraries explicitly override the default TYPE comparison.

FAQ