WinCC Grey Out Picture Elements: Parameter Disable via Script

Problem Overview: Greying Out WinCC Picture Parameters

In Siemens WinCC HMI/SCADA projects, operator panels commonly expose a group of parameters as I/O fields or symbolic text fields on a Picture (the WinCC term for a screen). When the design requires that only one parameter in a set of seven be adjustable at any moment, the remaining six fields must remain visible but become inoperable. The visual effect mirrors that of a disabled command button: the field background shifts to a neutral grey tone and the cursor no longer triggers the configured input mechanism, while the displayed value continues to update from the underlying tag.

The challenge is producing this behaviour on parameter elements that are not buttons — particularly on standard I/O fields and symbolic text fields where the runtime does not expose a built-in toggle identical to a command button's Operator-Control Enable. Two distinct approaches resolve the issue across WinCC V7 (Classic), WinCC Runtime Advanced (TIA Portal), and WinCC Runtime Professional (TIA Portal):

1. Set the Operation property of the I/O field to No and switch the BackColor to a defined grey RGB constant. The element remains on screen but accepts no operator input.
2. Use a VBScript or C script procedure invoked from a button-click, value-change, or picture-open event to iterate over a known set of items on the Picture and toggle each item's Operation and BackColor attributes dynamically.

This article documents both approaches with field-tested code samples, parameter tables, version compatibility notes, and a troubleshooting matrix that addresses the most common script errors encountered during commissioning.

Prerequisites and WinCC Environment

Software and Runtime Versions

Hardware Targets

• SIMATIC Comfort Panels: TP700, TP900, TP1200, TP1500, TP1900, TP2200
• SIMATIC Advanced Panels: KTP400, KTP700, KTP900, KTP1200
• SIMATIC IPC series for PC Runtime
• Standard Windows 10/11 PC stations running Runtime Professional

Licensing

• WinCC V7: Engineering license + Runtime license (RC 1024 / 8192 / 65536 tags)
• Runtime Advanced: Panel-specific license embedded in panel firmware
• Runtime Professional: ES + RT 128 / 512 / 2048 / 4096 tags
• WinCC Unified: ES + RT 500 / 1500 / 5000 / 10 000 / 50 000 / 100 000 PowerTags

Picture Element Naming Requirements

Each parameter field must carry a unique object name. Adopt a deterministic naming convention such as IOField_1, IOField_2, ..., IOField_7. The naming convention lets the script locate elements through the ScreenItems collection without relying on the object's display position. For faceplate-based panels, propagate the parameter index through the faceplate tag interface.

Static Configuration: Set the Operation Property Manually

The simplest approach disables the field at configuration time. Open the I/O field properties dialog in the Graphics Designer (WinCC V7) or the HMI screen editor (TIA Portal). Navigate to Properties > Miscellaneous and set the Operation property to No. To match the visual appearance of a disabled button, change Background > BackColor to a grey RGB constant such as RGB(192, 192, 192).

This static approach is suitable when the disabled state never changes at runtime — for example, when only an engineer password unlocks the field. When the disabled state must toggle based on operator input, use the dynamic VBScript approach documented in the next sections.

Dynamic Approach: VBScript for Individual Parameter Disabling

Trigger the Script on Button Click

Configure a button on the Picture and assign a Click event. From the event list, select VB Script (or C Script in WinCC V7). Paste the following VBScript as the procedure body:

Sub OnClick(ByVal Item)
    Dim sScreenPath, sItemName
    Dim intSelected
    Dim i
    
    sScreenPath = "MainPicture"     ' Replace with the actual Picture name
    intSelected = 3                 ' Selected parameter index 1..7
    
    For i = 1 To 7
        sItemName = "IOField_" & i
        Dim objItem
        Set objItem = HMIRuntime.Screens(sScreenPath).ScreenItems(sItemName)
        
        If i = intSelected Then
            objItem.Operation = True
            objItem.BackColor = RGB(255, 255, 255)
        Else
            objItem.Operation = False
            objItem.BackColor = RGB(192, 192, 192)
        End If
    Next
End Sub

The loop binds the parameter count (1 to 7) to the naming convention (IOField_1 through IOField_7). The Operation property is exposed by I/O field, text field, and symbolic I/O field objects.

Runtime Advanced Variant for Comfort Panels

In WinCC Runtime Advanced, the script interface uses the same HMIRuntime.Screens namespace. The selected index is typically read from an HMI tag rather than a literal constant:

Sub Click(ByVal Item)
    Dim i, objItem
    
    For i = 1 To 7
        Set objItem = HMIRuntime.Screens("MainPicture").ScreenItems("IOField_" & i)
        
        If i = SmartTags("TagSelectedParam") Then
            objItem.OperatorControl = True
            objItem.BackColor = RGB(255, 255, 255)
        Else
            objItem.OperatorControl = False
            objItem.BackColor = RGB(192, 192, 192)
        End If
    Next
End Sub

Another control writes the operator's selected parameter index to TagSelectedParam. The Click event on the I/O field or a dedicated selection button updates the tag, and the procedure re-evaluates all seven fields.

Generic Loop Routine: Iterating the ScreenItems Collection

To avoid hard-coding the seven I/O field names, iterate over the ScreenItems collection. The collection supports the standard For Each loop in VBScript:

Sub GrayOutAllExcept(ByVal sScreenName, ByVal sSelectedItem)
    Dim objScreen, objItem
    Set objScreen = HMIRuntime.Screens(sScreenName)
    
    For Each objItem In objScreen.ScreenItems
        If TypeName(objItem) = "HMIIOField" Or TypeName(objItem) = "HmiTextField" Then
            If objItem.Name = sSelectedItem Then
                objItem.Operation = True
                objItem.BackColor = RGB(255, 255, 255)
            Else
                objItem.Operation = False
                objItem.BackColor = RGB(192, 192, 192)
            End If
        End If
    Next
End Sub

Inline SVG Flow Diagram

Passing the Picture Name as a Parameter

Sub UpdateParameterStates(ByVal sScreenName, ByVal intSelected)
    Dim i, objItem
    
    For i = 1 To 7
        Set objItem = HMIRuntime.Screens(sScreenName).ScreenItems("IOField_" & i)
        
        If i = intSelected Then
            objItem.Operation = True
            objItem.BackColor = RGB(255, 255, 255)
        Else
            objItem.Operation = False
            objItem.BackColor = RGB(192, 192, 192)
        End If
    Next
End Sub

Call this routine from any event handler on any picture:

Sub OnClick(ByVal Item)
    UpdateParameterStates "MainPicture", 3
End Sub

For pop-up screens launched through the OpenScreenInPopup or picture-window mechanism, pass the active screen name via HMIRuntime.BaseScreenName or the picture-window's ScreenName property.

Alternative: Semi-Transparent Overlay Box

Another engineering pattern is to overlay a rectangle (or graphic view) on top of the parameter group with a semi-transparent fill. The overlay blocks mouse input to the underlying fields and produces an immediate visual grey effect. Implementation steps:

1. Add a Rectangle object to the Picture and size it to cover the parameter group bounding box.
2. Set the rectangle's BackColor to RGB(200, 200, 200) and apply a transparency attribute of approximately 50 percent through the colour palette transparency slider.
3. Place the rectangle on the topmost z-order layer (right-click > Bring to Front).
4. Show or hide the rectangle via objRect.Visible = True/False in the script.

The advantage is no per-element loop and immediate coverage of any new fields placed under the rectangle. The disadvantage is that the rectangle intercepts all clicks, so the selection button must reside outside the rectangle's area, or the rectangle must allow click-passthrough in Runtime Advanced (set Operator-Control Enable = No on the rectangle).

Color Reference: BackColor RGB Values

The RGB values must match the project colour palette defined in the Graphics Designer. Use the Tools > Customise > Colour Palette dialog to centralise custom colours and keep references consistent between design-time and runtime.

WinCC Version Compatibility Matrix

C Script Equivalent for WinCC V7

WinCC V7 also supports ANSI-C scripts. The equivalent routine uses SetPropBOOL to flip Operation and SetBackColor via the dynamic dialog function set:

// WinCC V7 - C Script
#include "apdefap.h"

void GrayOutParameters(const char* lpszPictureName, int nSelectedIndex)
{
    int i;
    char szItemName[32];
    
    for (i = 1; i <= 7; i++)
    {
        sprintf(szItemName, "IOField_%d", i);
        
        if (i == nSelectedIndex)
        {
            SetPropBOOL(lpszPictureName, szItemName, "Operation", TRUE);
            SetBackColor(lpszPictureName, szItemName, CO_RGB(255, 255, 255));
        }
        else
        {
            SetPropBOOL(lpszPictureName, szItemName, "Operation", FALSE);
            SetBackColor(lpszPictureName, szItemName, CO_RGB(192, 192, 192));
        }
    }
}

C scripts require the include header apdefap.h and the runtime function library distributed with WinCC V7. Documented APIs include SetPropBOOL, GetPropBOOL, SetBackColor, and SetForeColor for colour manipulation.

WinCC Unified JavaScript Equivalent

WinCC Unified uses a JavaScript-based runtime API. The property Enabled replaces Operation, and the screen object is accessed through the Screen module:

// WinCC Unified V19+ - JavaScript
export function Click_Trigger_1(item) {
    let screen = Tags("ScreenNumber").Read();
    let selected = Tags("TagSelectedParam").Read();
    
    for (let i = 1; i <= 7; i++) {
        let ioField = Screen.FindItem("IOField_" + i);
        if (i === selected) {
            ioField.Enabled = true;
            ioField.BackColor = 0xFFFFFFFF; // ARGB white
        } else {
            ioField.Enabled = false;
            ioField.BackColor = 0xFFC0C0C0; // ARGB grey
        }
    }
}

WinCC Unified uses ARGB colour encoding (alpha + RGB). The alpha channel supports the semi-transparent overlay pattern directly without a separate transparency slider.

Verification Steps

1. Compile the project in the Engineering Station and download it to the target panel or start the PC Runtime.
2. Navigate to the picture containing the parameter group.
3. Verify the initial state: all seven fields appear in their default colour, and only the configured active field accepts operator input.
4. Tap a different field. The previously active field should grey out (BackColor = RGB(192,192,192), Operation = False), and the newly tapped field should accept input.
5. Check the WinCC diagnostic window (WinCC V7) or the HMI trace (TIA Portal) for any script errors. Common errors include Object doesn't support this property or method when the property name does not match the runtime version.
6. Confirm that the back colour persists across picture changes. WinCC resets runtime properties when a picture is closed and reopened. Re-apply the property in the Picture Open event by reading a persistent tag (TagSelectedParam) and updating the BackColor accordingly.
7. Test edge cases: parameter index out of range (0 or 8), non-existent screen name, empty parameter set, picture change while a script is mid-loop.
8. Verify that the script does not produce screen flicker by avoiding BackColor updates from a high-frequency tag-change event.

Performance Considerations

For pictures with hundreds of screen objects, prefer explicit name references over enumeration. For pictures with ten or fewer items, enumeration is acceptable and yields more maintainable code.

Troubleshooting Matrix

Best Practices for Commissioning

• Naming convention: Prefix all parameter elements with a common identifier (param_ or IOField_) so the script can iterate deterministically without relying on visual position.
• Event selection: Attach the script to a discrete event (button Click) rather than a periodic tag update, to avoid runtime overhead and screen flicker.
• BackColor stability: Avoid animations that reapply BackColor every cycle; this causes visible flicker and increases CPU load on Comfort Panels.
• Read-only display: For elements that should remain visible but never accept input, set Operation = False and skip the loop entirely with a single static configuration.
• Audit trail: Log the operator's parameter selection to a tag with a timestamp; this supports GxP / CSV-regulated environments and traceability audits.
• Migration verification: When migrating a project from WinCC V7 to TIA Portal, the property Operation may map to OperatorControl or Enabled depending on the target panel. Verify each screen object after migration with the project diff tool.
• Style templates: Use the TIA Portal Style template feature (WinCC Unified) or the WinCC V7 style editor to centralise the enabled/disabled colour palette across all parameter panels.

Migration from WinCC V7 to TIA Portal

After migration, recompile the project and test each parameter panel. The TIA Portal Project > Compile > Software (all) tool reports unused references and obsolete API calls. Pay special attention to CO_RGB macro calls in C scripts — these require manual conversion to RGB literals when migrating to Runtime Advanced.

Documentation References

Siemens official WinCC documentation is published through the Siemens Industry Online Support portal. Search the portal for "WinCC V7.5 manual", "WinCC Runtime Advanced manual", "WinCC Unified V19", and "WinCC scripting reference". The WinCC object model (HMIRuntime, Screens, ScreenItems) is documented in the WinCC Information System help installed with the engineering software.

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