Reading and Editing User-Defined Block Icon Attributes via VBA in WinCC Graphics Designer

Attempting to read user-defined attributes such as 'TagNameDisplayed' using 'objObject.TagNameDisplayed' in WinCC Graphics Designer VBA produces runtime error 438 ('Object doesn't support this property or method') because 'TagNameDisplayed' is not a native COM property of 'HMIObject'. To correctly read and modify user-defined or dynamic properties in VBA, access the object's 'Properties' collection using the syntax 'objObject.Properties("TagNameDisplayed").Value'. This allows automated batch auditing and renaming of APL block icon labels across all process displays.

Executive Summary

During large-scale PCS 7 commissioning or plant standardization projects, automation engineers frequently write Visual Basic for Applications (VBA) macros inside WinCC Graphics Designer to automate repetitive tasks, such as renaming tags or updating display labels on hundreds of block icons. However, developers attempting to read customized APL properties—such as TagNameDisplayed—often hit a programming roadblock: the standard VBA object accessor throws Error 438: Object doesn't support this property or method. This article explains the internal object model of WinCC Graphics Designer, contrasts native COM properties with dynamic property collections, and provides production-ready VBA scripts to batch-edit block icon attributes.

Architectural and System Mechanics

WinCC Graphics Designer Object Model Architecture:

HMIObject Interface: Represents any graphical element (rectangle, circle, customized block icon, OLE control) placed on a .pdl picture screen.
Native Properties vs. Dynamic Property Collection:
Native Properties: Directly exposed via COM interface methods (e.g., objObject.ObjectName, objObject.Layer, objObject.Width, objObject.Height, objObject.Type).
Dynamic / User-Defined Properties: Custom attributes added to grouped or customized objects (such as TagNameDisplayed, ServerName, Type, HighlightColor) do NOT exist as direct COM methods. Instead, they reside in the objObject.Properties collection.
Correct Access Syntax: objObject.Properties("TagNameDisplayed").Value.
Error 438 Mechanism: Calling objObject.TagNameDisplayed forces VBA to query the early-bound COM dispatch table of HMIObject, which lacks this member, throwing Error 438 immediately.

Step-by-Step Engineering and Implementation Procedure

Step 1: Open the VBA Editor in Graphics Designer

Open any process display picture in WinCC Graphics Designer.
Press Alt + F11 to launch the integrated Microsoft Visual Basic for Applications (VBA) editor.
Insert a new module under VBA-Project (<PictureName>.pdl) -> 'Modules' -> 'Module1'.

Step 2: Implement the Safe Attribute Reader Macro

Write a VBA routine that iterates through all objects on the screen, checks for the existence of TagNameDisplayed, and reads its value:

Sub ReadAllTagNamesDisplayed()
    Dim objObject As HMIObject
    Dim objProp As HMIProperty
    Dim strTag As String

    For Each objObject In ActiveDocument.HMIObjects
        On Error Resume Next
        Set objProp = objObject.Properties("TagNameDisplayed")
        On Error GoTo 0

        If Not objProp Is Nothing Then
            strTag = objProp.Value
            Debug.Print "Object: " & objObject.ObjectName & " | TagNameDisplayed: " & strTag
            Set objProp = Nothing
        End If
    Next objObject
End Sub

Step 3: Implement Batch Attribute Modification Script

To batch-modify prefixes or strip chart names across all icons on the screen:

Sub BatchModifyTagNameDisplayed()
    Dim objObject As HMIObject
    Dim objProp As HMIProperty

    For Each objObject In ActiveDocument.HMIObjects
        On Error Resume Next
        Set objProp = objObject.Properties("TagNameDisplayed")
        On Error GoTo 0

        If Not objProp Is Nothing Then
            ' Example: Replace prefix "OLD_" with "NEW_"
            If InStr(objProp.Value, "OLD_") > 0 Then
                objProp.Value = Replace(objProp.Value, "OLD_", "NEW_")
            End If
            Set objProp = Nothing
        End If
    Next objObject
    ActiveDocument.Save
End Sub

Step 4: Execute Macro and Review Output

Run the macro via F5 in the VBA editor. Inspect the Immediate Window (Ctrl + G) to verify all parsed tags.

Verification

To verify macro execution:
1. Check the Immediate Window in the VBA editor; confirm that all block icons report their custom display strings without throwing Error 438.
2. Switch to Graphics Designer; select a modified block icon and inspect its Object Properties window under 'System' -> 'TagNameDisplayed'.
3. Confirm that the text field reflects the script's updated string.
4. Save the picture and verify display appearance in WinCC Graphics Runtime.

Limitations and Operational Precautions

Operational precautions:
- Modifying TagNameDisplayed alters only the text label shown on screen; it does NOT alter the underlying runtime connection tag (Tag), leaving process communication unaffected.
- Always create a backup of the .pdl picture file before executing batch modification macros.
- Rerunning 'Create/Update Block Icons' in SIMATIC Manager will overwrite custom TagNameDisplayed values unless block icon rules in the Plant Hierarchy are synchronized.

Engineer FAQ

Q: Why did `objObject.TagNameDisplayed` trigger Error 438?

A: Because TagNameDisplayed is a user-defined property stored within the Properties collection, not a direct COM method of HMIObject.

Q: Can this VBA script run in WinCC Runtime?

A: No. VBA macros execute inside Graphics Designer during engineering. For runtime actions, use C-Script or VBScript (using ScreenItems("Object").TagNameDisplayed).

Q: How do I check if an object possesses a specific property?

A: Use On Error Resume Next, attempt to set objProp = objObject.Properties("PropertyName"), and check If Not objProp Is Nothing.

Q: Can VBA edit properties across multiple `.pdl` files automatically?

A: Yes, by utilizing Documents.Open within a VBA loop over all files in the GraCS directory.

Q: Does changing this property modify CFC block comments?

A: No. VBA edits the WinCC graphic display properties only; controller CFC configurations are unchanged.

Technical References

Related Tags

WinCC VBA, TagNameDisplayed, HMIObject, Error 438, Graphics Designer

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Reading and Editing User-Defined Block Icon Attributes via VBA in WinCC Graphics Designer