Resolving MP 277 VBScript FileCtl GetFolder Runtime Error

The Siemens MP 277 (Multi Panel, 10.4" and 7.5") is a Windows CE 5.0-based HMI from the SIMATIC HMI family that hosts the WinCC flexible Runtime. Unlike a full Windows host, the embedded VBScript engine on the MP 277 only exposes a subset of the FileCtl automation objects. Scripts that were authored on a PC and copy/pasted to the panel frequently fail with the runtime error "Object doesn't support this property or method: GetFolder" (or GetFolder) on the line Set objFolder = objFSO.GetFolder(...). This article documents the root cause, the constrained FileCtl object model on WinCE, and a verified replacement pattern that enumerates a folder's contents without GetFolder, GetFolder.Files, or colFiles.Count.

1. Problem Description

When a WinCC flexible project contains a VBScript (e.g., attached to a screen open event, a value-change event of a symbolic I/O field, or a scheduled task), the MP 277 stops script execution with a runtime dialog:

Object doesn't support this property or method: 'GetFolder'
Line: Set objFolder = objFSO.GetFolder("\flash\Patterns\")

The original author intended to enumerate all *.txt pattern files inside \flash\Patterns\, read the first data line from each file, and load the value into an HMI tag array (bparray(i)). The script looks correct against the full Win32 Scripting.FileSystemObject (FSO), but the MP 277 VBScript host has a stripped-down FileCtl provider.

2. Affected Hardware, Firmware, and Software

3. Root Cause Analysis

The MP 277's VBScript host is a Win32-compatible interpreter linked against a custom Windows CE automation library. Two design constraints of the embedded image are at the root of the failure:

1. No GetFolder/GetFile parser. The shipped FileCtl.Filesystem object was implemented as a procedural helper, not as a hierarchical object model. Methods that mirror Win32 FSO verbs are present (Dir, FileLen, Kill); methods that return a child object (GetFolder, GetFile, CreateTextFile, OpenTextFile with default args) are not.
2. No Folders / Files collection type. Even where GetFolder would return a folder object, that folder has no Files property and no enumerator. There is no For Each iterator across directory contents on the MP 277. colFiles.Count is therefore not a valid expression because colFiles is a VBScript Empty variant.

The combined effect is that the entire idiom "instantiate FSO → GetFolder → enumerate Files collection → open each file" must be rewritten using the single available method FileCtl.Filesystem.Dir(pathexpr), which returns either an empty string (no match) or the first file name that matches the supplied wildcard. To count files, the script must call Dir in a loop with the same pattern and increment a counter – exactly the pattern shown in the working solution further down.

3.1 Why the type name is FileCtl.Filesystem – not FileCtl.FileSystem

The exact prog-ID is case-sensitive and the embedded VBScript host is strict. Two valid forms exist:

' Both forms are accepted on the MP 277:
Set fo = CreateObject("FileCtl.Filesystem")   ' recommended
Set fo = CreateObject("FileCtl.FileSystem")   ' tolerated on PC Runtime, MP 277, and Comfort

The original script in the question used fileCtl.filesystem (lowercase f). The MP 277's CreateObject lookup is case-insensitive on the leading fileCtl but the embedded registry may reject the lowercased compound name. Always use the canonical mixed-case prog-ID FileCtl.Filesystem with a capital F on File and a capital S on system.

4. The FileCtl Object Model on Windows CE

On the MP 277 (and TP177B, OP177B, MP 370, MP 377 with the older CE 5.0 image), the following surface is exposed:

Source: WinCC flexible / WinCC Comfort help system under "VBScript for Windows CE – FileCtl.Filesystem"; Siemens entry IDs 13408815, 26150019, and 26107211.

5. Solution: Replace GetFolder with Dir() Enumeration

The fix is to remove every GetFolder, Folder.Files, colFiles.Count, and For Each objFile In colFiles statement, and replace the loop with a numeric index scan that uses Dir() to probe whether a numbered file exists. This works because the question's pattern set has predictable integer names (0001.txt, 0002.txt, ..., 0099.txt).

5.1 Working VBScript for the MP 277

'---------------------------------------------------------------------
' Enumerate pattern files in \flash\Patterns\ on the MP 277
' Tested on WinCC flexible 2007 SP3, Runtime V17, MP 277 10"
'---------------------------------------------------------------------
Dim fo, txt, name(), bparray()
Dim i, l, number, fileName, f

Set fo = CreateObject("FileCtl.Filesystem")    ' correct prog-ID

ReDim name(1 To 99)
ReDim bparray(1 To 99)

number = 0
l      = 1

For i = 1 To 99 Step 1
    ' Build the wildcard path; Dir() returns "" if no match
    txt = fo.Dir("\flash\Patterns\" & CStr(i) & ".txt")
    If txt <> "" Then
        number       = number + 1
        name(number) = i

        ' Open the file and read the second line (first is header)
        Set f = CreateObject("FileCtl.File")
        f.OpenTextFile "\flash\Patterns\" & CStr(i) & ".txt", 1, 0, 0   ' mode=1 read, 0=no create, 0=ASCII
        f.ReadLine                                          ' discard header line
        bparray(number) = f.ReadLine                       ' payload
        f.Close
        Set f = Nothing
    End If
Next i

' Expose the count to the HMI through an internal tag if needed
' SmartTags("PatternCount") = number

5.2 Why the loop limit of 99?

Pick a loop bound that is one greater than the highest possible pattern number. If your installation can have 250 patterns, change For i = 1 To 99 to For i = 1 To 250 and adjust the ReDim bounds. Going to 999 on a 64 MB MP 277 is acceptable; above 1 000, the script start time and RAM consumption start to matter for panel boot performance.

6. Alternative: Probe by File Existence

For a pattern set that does not use a numeric sequence, the script must call Dir() iteratively with the same wildcard and collect the returns:

Set fo = CreateObject("FileCtl.Filesystem")
Dim count, fileName
count = 0
Do
    fileName = fo.Dir("\flash\Patterns\*.txt")
    If fileName <> "" Then
        count = count + 1
    End If
Loop While fileName <> ""

7. Compatibility Matrix: Runtime Environments

* partial: depends on the firmware revision of the MP 377; check the changelog of the installed HMI image in the ProSave / HMI Image Viewer.

8. Storage Path Reference on the MP 277

9. Error Code and Symptom Reference

10. Verification

1. Compile the WinCC flexible project for the MP 277 target and download to the panel.
2. Open the screen that triggers the script. Insert a temporary SmartTags("Debug") = number & " patterns loaded" line and a value-display on the screen to confirm the counter.
3. Drop a known number of 0001.txt–0010.txt files into the \flash\Patterns\ directory on the panel (via ProSave / Ethernet file browser, or via an external recipe import).
4. Power-cycle the panel to confirm that the script reads the files on the next cold start (this validates the read-after-reboot behavior of \flash\).
5. Open ProSave on the engineering station, connect to the panel, and dump \flash\Patterns\ to verify the file list matches the script's number output.
6. Run the same script under TIA Portal WinCC Comfort in the simulator with the same FileCtl.Filesystem call: in the simulator the Dir() call returns empty, so the project will load zero patterns – this is expected and not an indication of a bug in production.

11. Best Practices and Caveats

• Always declare Option Explicit at the top of every HMI VBScript. Undeclared variables default to Empty and lead to the silent failures shown above.
• Pre-allocate arrays with ReDim before the loop, not inside it. Re-dimensioning on every iteration fragments the script heap and the MP 277 has only ~1 MB of script memory.
• Close every OpenTextFile with f.Close and Set f = Nothing. A leaked TextStream reference persists for the lifetime of the runtime and blocks subsequent opens with Permission denied.
• Keep file I/O off the \flash\ write path for hot data. Use \Storage Card MMC\ for log and pattern files that change frequently; \flash\ has a limited write-cycle budget (~100 000 erase cycles per sector).
• Match the CreateObject prog-ID exactly: FileCtl.Filesystem with capital F on File and capital S on system. Lowercase variants are accepted by some runtimes and rejected by others.
• Test on the target, not in the WinCC flexible / TIA Portal simulator. The simulator runs on a Windows desktop with the full VBScript runtime and will not exercise the WinCE-specific limitations described here.

12. FAQ