TP900 Comfort: Dynamic Recipe Export Filenames to Network Share

1. Problem Overview

Siemens SIMATIC TP900 Comfort panels (and the broader Comfort Panel family, 6AV2 124-1MC01-0AX0 and successors) ship with a recipe subsystem that supports exporting the currently loaded record set to CSV files via the ExportDataRecords system function. The default configuration writes the export to a fixed path and a fixed filename, which causes two field issues:

1. Every export overwrites the previous file because the filename is constant (e.g. record.csv).
2. The exported file does not identify which recipe it came from, so post-processing scripts cannot disambiguate records on the server side.

The desired behavior is a base path of \\network\logs\ combined with a recipe-specific filename, for example \\network\logs\Recipe_42.csv, sourced from an HMI tag that holds the current recipe name. This article documents the full configuration chain, the script-based workaround needed because the system function does not accept a runtime-built string directly from a button event, and the network/permissions prerequisites that frequently block the export silently.

2. Prerequisites

3. Anatomy of ExportDataRecords

The ExportDataRecords system function is one of the documented recipe operations in the Comfort Panel programming reference. Its signature in TIA Portal exposes three input parameters visible in the configuration dialog:

The dialog accepts a literal string or an HMI tag for each parameter, but it does not accept a string expression. This is the architectural reason that a button event cannot directly pass "\\network\logs\" & Sname & ".csv": the system function expects either a constant or the full content of a tag, not a concatenation result. The accepted engineering pattern is therefore to pre-assemble the complete path into a single HMI tag before calling the system function, and select that tag as the Name source.

4. Configuring the Filename HMI Tag

1. In the project tree, open HMI Tags → Default tag table.
2. Add a new tag. Name it Sname (or any identifier consistent with your project).
3. Set Data type to WString[254] — Windows-style strings are required for UNC paths; String is acceptable for short recipe names but offers no Unicode support.
4. Set Length to a value that accommodates the full path. For a 64-character path plus 64-character recipe name, WString[254] is a safe ceiling.
5. Set Acquisition mode to Cyclic continuous if the PLC will write the recipe name continuously, or leave as On demand if the script will populate it.
6. Add a second tag Spath with the same data type to hold the fully assembled path string \\server\logs\Sname.csv.

5. Building the Path String

Two patterns are field-proven. The first writes the recipe name to Sname and concatenates a constant base path on the panel side. The second computes the full path in the PLC and writes the result to Spath directly.

5.1 PLC-side concatenation (S7-1200 / S7-1500)

Use the Siemens standard CONCAT string functions. In SCL:

// Inputs
VAR_INPUT
    iRecipeName : String;   // e.g. 'Recipe_42'
END_VAR

VAR_TEMP
    tBase : String := '\\\\server\\logs\\';
    tExt  : String := '.csv';
END_VAR

// Build path into Sname (WString-compatible via implicit conversion on the HMI tag)
Sname := CONCAT(IN1 := CONCAT(IN1 := tBase, IN2 := iRecipeName), IN2 := tExt);

The four-character sequence \\\\ in a string literal represents two literal backslashes when the panel runtime receives the string, producing a valid UNC prefix.

5.2 HMI-script-side concatenation (VBScript on the panel)

Comfort Panels support VBScript inside scheduled tasks and as the action of an event. The script below can be assigned to a button's Press event directly:

Dim base, ext, full
base = "\\\\server\logs\\"
ext  = ".csv"

' Read recipe name from HMI tag
Dim sName
sName = SmartTags("Sname")

' Build the full path
full = base & sName & ext

' Write to the HMI tag consumed by ExportDataRecords
SmartTags("Spath") = full

' Now invoke the system function
SmartTags("RecipeExportTrigger") = True

The RecipeExportTrigger tag is a Boolean wired to a second event on the same button (or a separate button) that calls ExportDataRecords with Name = HMI_Tag bound to Spath. This indirection is required because TIA Portal does not allow a button event to call a system function with a tag value that was just modified in the same handler — the value is read at compile time of the call.

6. Avoiding Overwrites

Even with a unique recipe name, two consecutive exports of the same recipe will collide. The engineering solutions, in order of preference:

1. Disable overwrite. In the ExportDataRecords dialog, set the Overwrite parameter to false. The function will then return an error if the file exists, which can be caught and presented to the operator.
2. Append a timestamp. Build the filename as Sname & "_" & FormatDateTime(Now, "yyyymmdd_hhnnss") & ".csv". The Now() function is available in the panel's VBScript environment and returns the panel's local time.
3. Append a sequence number from the PLC. Maintain a counter in the PLC and concatenate it. Less elegant but deterministic, which simplifies downstream audit trails.

For a regulated batch environment, combine approaches 1 and 2: disable overwrite and also include a millisecond counter or PLC-side monotonic timestamp to guarantee uniqueness even if the operator double-taps the export button within the same second.

7. Network Share and Permission Setup

The most common field failure for recipe export to a network share is not the HMI logic — it is the SMB / authentication layer. Apply the following checklist:

1. Create the share on the Windows host, e.g. \\SERVER\RecipeLogs.
2. Grant Modify (not just Read & Execute) to the user account the panel will authenticate as. Modify is required because ExportDataRecords creates a new file; read-only shares will return an ERROR_ACCESS_DENIED in the panel's log.
3. Set NTFS permissions matching the share permissions. A common error is granting Share-level access while the folder's Security tab denies write.
4. Configure the panel's network identity: in the panel project, Devices & Networks → select the HMI → Properties → Network & Identity. Enable User authentication and enter the domain account, e.g. DOMAIN\hmi-service. The password is supplied through ProSave or the configuration download.
5. Verify DNS resolution from the panel: open the panel's Control Panel → Network & Dial-Up Connections and ping the server. The ping tool on WinCE-based Comfort Panels uses ICMP and will report host resolution failures.
6. Disable SMBv1 on the server if you are running a modern Windows host. Comfort Panels default to SMBv2; mismatched protocol versions cause STATUS_BAD_NETWORK_NAME errors logged as event 14 in the HMI diagnostic buffer.

8. Verification Procedure

1. Compile and download the panel project to the TP900.
2. On the operator screen, load a recipe (e.g. Recipe_42).
3. Press the export button. Watch the Spath tag online value through TIA Portal's Online & Diagnostics view; it should read \\SERVER\RecipeLogs\Recipe_42.csv immediately before the export.
4. On the Windows server, open the RecipeLogs folder and confirm the file appears with a recent timestamp.
5. Load a different recipe (e.g. Recipe_43), repeat the export, and confirm a separate file is created.
6. Export Recipe_42 again with Overwrite disabled. The export should fail with a system event and the operator should see a configured alarm message.

For a scripted timestamp variant, also confirm by exporting the same recipe twice within one second: two distinct files should exist on the share.

9. Diagnostic Buffer Codes

WinCC Comfort logs recipe and file-system errors into the panel's diagnostic buffer. The most common codes and their meanings:

Open the diagnostic buffer via the panel's Control Panel → OP → System Properties → Device Status → Diagnostic Buffer, or remotely via ProSave's Backup / Restore view with the panel in transfer mode.

10. Troubleshooting Matrix

11. Advanced: Triggering Export from the PLC

To avoid a script on the panel entirely, the PLC can write Spath directly and a single area pointer or scheduler event on the panel can detect the change. The pattern is:

1. PLC writes the assembled path to Spath (HMI tag, WString).
2. PLC sets ExportTrigger (HMI tag, Bool) to true for one cycle.
3. A scheduled task on the panel polls ExportTrigger every 200 ms. On a rising edge, it calls ExportDataRecords with the Name parameter set to HMI_Tag bound to Spath.
4. Reset ExportTrigger from the PLC after a 500 ms delay, or from the panel script after a successful return code.

This pattern is more deterministic than a button event and is the recommended approach for production lines where the export is part of a batch end-of-step sequence.

12. Related Recipe Operations

Once ExportDataRecords is working, the mirror operation ImportDataRecords follows the same parameter logic: the Name can be bound to an HMI tag, allowing the PLC to select which CSV to load by writing the path to the tag. The Siemens TIA Portal V21 documentation lists the full matrix of import / export / clear / load / save system functions, and is the authoritative reference for the dialog parameter semantics used in this article.