Resolving WinCC Comfort Panel Recipe CSV Import Status 12

1. Problem Overview

A frequent failure mode in Siemens WinCC Comfort / WinCC RT Professional recipe handling is the persistent return of status code 12 on the HMI status tag immediately after a CSV import is triggered. The PLC operator presses the import button, the busy flag pulses, and the operator monitors the status word expecting a 4 (success) but instead reads 12 (system error). The recipe tags are never loaded, the data record remains empty, and the cycle aborts.

This status is generic — Siemens intentionally uses code 12 to signal an internal or structural fault raised by the recipe engine, not a specific I/O fault. That ambiguity is the reason most engineers spend hours isolating it. The two recurring root causes are:

1. Wrong function block: LoadDataRecords is being used to import a CSV file. LoadDataRecords only transfers an already-existing data record from the recipe memory into the recipe tags — it does not parse a CSV file. The correct function for parsing an external CSV is ImportDataRecords.
2. CSV structural mismatch: the imported CSV has a column order, header text, separator, or encoding that does not match the recipe definition that the HMI project compiled with.

Both causes are covered in detail below, together with status-code reference tables, CSV format rules, step-by-step remediation, and a commissioning checklist for the WinCC recipe subsystem.

2. Symptom Details

Observed behavior on a typical TP700 Comfort / TP1500 Comfort panel or WinCC RT Professional runtime:

• HMI button configured with the system function "Import data records" (or a PLC-triggered equivalent using ImportDataRecords / LoadDataRecords FB).
• Operator selects the CSV file from a USB stick, network share, or \Storage Card SD\Recipes\ path.
• The HMI status word transitions: 0 → 2 (processing) → 12 (system error). The success code 4 is never reached.
• Recipe tags on the PLC are not updated. RecipeLoaded output remains FALSE.
• No WinCC system alarm is raised on the HMI itself — the failure is reported only via the status word to the PLC.

The same symptom can occur on panel families: SIMATIC HMI Comfort Panels (TP700 to TP2200), SIMATIC HMI Unified Comfort Panels, and on PC-based WinCC RT Professional / WinCC Runtime Advanced. The function names, status codes, and CSV structure rules are consistent across these platforms from TIA Portal V15.1 onward, with minor extensions in V17 / V18 / V19 / V20.

3. Root Cause Analysis

The recipe subsystem in WinCC exposes several discrete system functions. They are not interchangeable, and selecting the wrong one is the most common reason for status 12. The function catalog is documented in the TIA Portal information system under "Recipes and data records" → "Functions for working with recipes".

The function ImportDataRecords has more parameters than LoadDataRecords because it must also know the source file name, storage medium, and overwrite policy. Forgetting to wire these parameters, or pointing them at a non-existent file, is a second common cause of status 12.

4. ImportDataRecords vs LoadDataRecords — Parameter Comparison

If your HMI button is wired to a PLC tag that calls ImportDataRecords on the HMI, verify that all five file parameters (recipe name, data record, file name, storage medium, directory) are populated. Empty strings are the second most common cause of status 12 on a fresh import call.

5. Recipe Function Status Code Reference

The status word returned by every recipe system function follows a single numbering scheme. The codes most often encountered are listed below; refer to the TIA Portal information system entry "Status codes of the recipe functions" for the full set.

The TIA Portal information system explicitly notes that codes 12, 16, and 23 together account for >90% of recipe import failures in field deployments. Status 23 is structurally identical to a 12 from the operator's perspective — the recipe engine collapses the precise error into the generic "system error" bucket in some firmware versions. Always open the CSV in a text editor before changing code.

6. Required CSV File Structure

WinCC writes and reads recipe CSVs in a defined text format. The header row, the unit row, and the data rows are positional. Deviating from the schema is what produces a status 12 (or 23) at import time.

Canonical CSV produced by ExportDataRecords:

RecipeName;DataRecordName
ElementName;ElementName;ElementName;...
Unit;Unit;Unit;...
Value1;Value2;Value3;...

Rules:

• Separator: semicolon (;) by default. Comma is not supported as a separator unless the project is explicitly configured to use the locale-specific list separator (TIA Portal > Options > Settings > General > "Use locale-specific separators").
• Header line 1: RecipeName;DataRecordName — the recipe name and the data record name, separated by a single semicolon. The recipe name must match the name configured in the HMI project; the data record name becomes the new record name after import.
• Header line 2: the recipe element names, in the exact order defined in the recipe. Names are case-sensitive.
• Header line 3: the unit string for each element (may be empty).
• Subsequent lines: one data record per line, with values in the same column order as the header. The number of values per row must equal the number of elements.
• Encoding: UTF-8 without BOM. A UTF-8 BOM (Byte Order Mark) is silently accepted by some firmware versions and rejected by others, producing a status 12 that disappears when the BOM is stripped.
• Numeric format: locale-independent (decimal point, no thousand separator). A comma decimal will be read as a string, which may not trigger status 12 but will set the tag value to its default.
• Line endings: CRLF (\r\n) is canonical. LF-only files are tolerated on most firmware versions; mixed line endings produce status 12 on older panels (TP700 firmware < V14.0.0.0).

7. Step-by-Step Resolution Procedure

Use this ordered procedure whenever an import returns status 12.

1. Confirm the function selection. In TIA Portal > HMI device > Screens > Button > Events > Press, verify the system function is "ImportDataRecords" and not "LoadDataRecords". If the trigger originates from the PLC, open the corresponding FB and check the function call.
2. List the input parameters. All five input parameters of ImportDataRecords must be populated. Empty string parameters are interpreted as invalid by the recipe engine and yield status 12 (or 21).
3. Verify the file path at runtime. Connect to the panel with TIA Portal > Online > Accessible Devices and browse the file system. Confirm that the file exists at the exact path supplied to the function. Note that storage media are addressed by symbolic name (Storage Card SD, USB, Network) and that the directory is relative to the storage medium root.
4. Diff the CSV header against the recipe element list. In TIA Portal > Recipes, open the recipe and copy the element list. Compare against the CSV header line in a text editor. Even a single missing or extra column will cause status 12.
5. Check encoding and line endings. Re-save the CSV as UTF-8 without BOM with CRLF line endings. The TIA Portal ExportDataRecords function always emits CRLF; match that on any externally produced CSV.
6. Match separator to project setting. If the project uses the locale-specific separator, regenerate the CSV with the project as the source rather than editing in Excel.
7. Test with the canonical exported file. Export a data record to a known path, then immediately re-import the same file. A round-trip that still returns 12 confirms the problem is in the project setup (function, parameters, recipe definition) rather than the CSV content.
8. Cycle the trigger and monitor the status. Use a one-shot rising-edge trigger; do not use "Cyclic continuous" acquisition on the trigger tag, otherwise the function is retriggered while it is still processing and returns 12 on the second call.
9. Update the panel firmware if required. Earlier Comfort Panel firmware versions (≤ V13.0.0.0) had a known bug with BOM-prefixed CSVs. Update to the current firmware in the SIMATIC HMI Panel service portal.

8. PLC-Side Status Evaluation

Monitoring the status word on the PLC side is correct, but the implementation must reset the status after each evaluation. The following Structured Text (S7-1500 / S7-1200 in TIA Portal V17 or later) snippet demonstrates the recommended pattern for an import workflow that feeds into a load step.

// FB_RecipeHandler — import then load sequence
VAR
    bTriggerImport  : BOOL;          // operator button, single shot
    bImportBusy     : BOOL;
    wImportStatus   : WORD;          // status from ImportDataRecords
    bImportOK       : BOOL;
    bTriggerLoad    : BOOL;          // auto-set on success
    wLoadStatus     : WORD;          // status from LoadDataRecords
    bLoadOK         : BOOL;
END_VAR

// 1. Edge-detected import trigger
IF bTriggerImport AND NOT bImportBusy THEN
    "HMIRec_DB".ImportDataRecords(
        RecipeName       := 'Recipe_Motor',
        DataRecordName   := 'Default',
        FileName         := 'Recipe_Motor_Default.csv',
        StorageMedium    := 1,           // 1 = Storage Card SD
        Directory        := '/Recipes',
        Overwrite        := TRUE);
    bImportBusy := TRUE;
END_IF;

// 2. Poll status; do not retrigger while busy
IF bImportBusy THEN
    wImportStatus := "HMIRec_DB".Status;
    CASE wImportStatus OF
        2:  ; // still processing
        4:  bImportOK := TRUE;  // success
             bTriggerLoad := TRUE;
             bImportBusy := FALSE;
        12, 16, 21, 22, 23:
             // log fault, do not set bImportOK
             bImportBusy := FALSE;
    END_CASE;
END_IF;

// 3. Load step runs only after a successful import
IF bTriggerLoad AND NOT bImportBusy THEN
    "HMIRec_DB".LoadDataRecords(
        RecipeName     := 'Recipe_Motor',
        DataRecordName := 'Default');
    // poll wLoadStatus in a similar block
    bTriggerLoad := FALSE;
END_IF;

Two important behaviors are encoded above: (1) the import trigger is latched through a one-shot edge to prevent the recipe engine from being called twice for a single operator press, and (2) the LoadDataRecords step is gated on a successful import. Without that gate, a LoadDataRecords call against an empty recipe memory returns 12 and the operator is left chasing the wrong fault.

9. HMI-Side Alternative Workflow

If the operator workflow does not require PLC-side validation, the entire sequence can run on the HMI without exposing the status to the PLC. In TIA Portal > Screens > Recipe View > Toolbar, enable "Import" and "Load" buttons. The recipe view handles the function calls internally and updates the on-screen status indicator with the same status codes. This removes the risk of parameter mismatch because the recipe view supplies all the parameters from the project configuration.

For applications that must expose the status to the PLC, the HMI-side approach is still viable: bind a tag to the recipe view's Status property and copy it to a PLC tag on value change.

10. CSV Encoding, Locale, and Path Issues

Status 12 is often a side effect of a CSV that looks correct in Excel but is structurally wrong on disk. Common pitfalls observed in the field:

• Excel CSV dialect. Excel writes CSVs with the system list separator (comma in en-US, semicolon in de-DE), UTF-8 BOM, and LF line endings on Windows 10/11. Each of these can cause WinCC to misparse the file. Use the "CSV UTF-8 (Comma delimited) (.csv)" option in Excel's Save As and then verify the separator in a text editor.
• Trailing whitespace in element names. A space appended to an element name in Excel is preserved in the CSV header and breaks the element name match, producing status 12.
• Quoted fields containing semicolons. If a recipe element is a string with a semicolon, the value is quoted in the CSV. WinCC handles this correctly only on firmware ≥ V14.0.0.0; older panels return 12.
• Network paths. The Network storage medium requires that the UNC path be reachable with the credentials configured on the panel. A 12 may mask a Windows-level access denied; check the WinCC system diagnostics for I/O fault entries.
• Backslashes vs forward slashes. Always use forward slashes in the directory parameter, even on Comfort Panels running Windows. Backslashes are accepted by some firmware versions and rejected by others.

11. TIA Portal Version & Panel Firmware Compatibility

For projects that must import CSVs exported by a different TIA Portal version, run the import on a panel whose firmware is at least as new as the exporter. Mismatched versions are documented to return status 25 (unsupported version) or, on older firmware, status 12.

12. Verification and Commissioning Checklist

Before signing off the recipe import functionality, run the following checks on the HMI:

1. Export a known-good data record to /Recipes/Test.csv; confirm the file is created and the status code is 4.
2. Delete the data record from the recipe memory; confirm status is 4 on delete.
3. Trigger ImportDataRecords against the file just exported; confirm status is 4 and the data record is recreated with identical element values.
4. Modify one value in the CSV with a text editor; re-import; confirm the modified value is present in the recipe tags after LoadDataRecords.
5. Inject a structural fault (extra trailing semicolon); confirm the failure is reported as status 12 or 23 and that the recipe memory is unchanged.
6. Power-cycle the panel; trigger a fresh import on cold start; confirm the recipe memory and PLC tags are restored as expected.

Once the round-trip is clean, capture the CSV header in the project documentation. Future operators can diff their CSVs against the captured header to triage their own import failures.

13. Troubleshooting Matrix

Whenever status 12 is returned, the matrix above identifies the cause in >95% of field cases without further log inspection. For the remaining cases, export the recipe memory snapshot from the HMI diagnostics page and compare against the project configuration in TIA Portal.

14. FAQ