Configuring Data Logging and Trend Recall on Siemens Comfort

1. System Overview and Use Cases

Continuous process monitoring on a Siemens SIMATIC Comfort Panel (TP700, TP900, TP1200, TP1500, TP1900, TP2200) requires three coordinated functions inside TIA Portal and WinCC:

1. A live trend view that plots the current value of one or more tags against the time axis at the panel runtime.
2. A data log that archives the same tag values to a non-volatile file (typically CSV) on the SD card or internal flash, triggered by time or by a tag-driven event.
3. A historical trend view that re-reads the archived log file and displays the value curves for a user-selected start and end time.

For the spec in the source post (5 process tags, continuous plot, user-initiated archive recall, printable export), the Comfort Panel family handles the entire workflow natively - no separate SCADA server is required when the trend volume fits the SD card budget. When volume, multiple users, central reporting, or external database access are required, the design must escalate to WinCC Runtime Professional on a PC or to a SCADA such as AVEVA. This article covers the embedded Comfort Panel path, including the SD-card sizing, file format, report job, and CSV export procedures that satisfy the original five-tag requirement.

2. Hardware Prerequisites

3. Software Prerequisites

• TIA Portal with the "WinCC Comfort" or "WinCC Advanced" option package installed (the Comfort package covers all panels up to TP1500; Advanced is required for PC Runtime and for tag counts above the Comfort limit).
• Panel image version equal to or newer than the TIA Portal version generating the project. Each TIA Portal release ships a specific WinCC RT image; the project download only succeeds if the panel image version is >= the project's RT version.
• Access to the panel's Control Panel via the Maintenance menu to enable the data log path and to confirm the file system after the first download.

Refer to the official SIMATIC HMI Comfort Panels Operating Instructions entry on the Siemens Industry Online Support portal for hardware and image compatibility.

4. TIA Portal Project Configuration

1. Open TIA Portal and add the Comfort Panel device to the project tree. Select the device version that matches the physical hardware (TP700 Comfort, 6AV2 124-1GC01-0AX0, firmware matching your installed TIA Portal).
2. Right-click the HMI device and choose Properties > General > HMI device information and verify the Runtime version.
3. Open Runtime settings > Services > Data log and set the storage path to \Storage Card SD\Logs\. Internal flash path \Flash\Logs\ is also available, but the SD card is recommended because it survives a panel firmware update.
4. Under Runtime settings > Services > Report, confirm the PDF storage path: \Storage Card SD\Reports\.

5. Configuring HMI Tags as Trend Sources

The five process tags can be sourced from any HMI tag whose value originates from the PLC. Each tag needs to be declared in the HMI tag table with the appropriate acquisition mode.

For an S7-1500, link the tag to a DB element via the PLC tag. For an S7-1200 or third-party PLC, link to a defined DB or holding register. The HMI tag's PLC tag column auto-populates when the connection is configured.

6. Configuring the Data Log

1. In the project tree, open HMI tags > Data logs and add a new data log named ProcessArchive.
2. Add a column for each of the five process tags. Set column format to Float or Integer matching the tag type.
3. Open the data log properties and configure:
   • Storage path: \Storage Card SD\Logs\
   • Storage mode: Sequential (circular) for continuous overwrite, or segmented for one file per day
   • Trigger: Time-based, 1 s, or a tag-driven event using a Boolean trigger tag from the PLC
   • Record count per file: 86,400 (one row per second for 24 hours if cycle = 1 s)
4. For the segmented mode, set the segmentation to Day; the panel automatically rolls over at midnight and creates a new file ProcessArchive_YYYYMMDD.csv.

6.1 CSV Layout Produced by WinCC Comfort

The default separator is a tab character when opened inside the panel; when exported to a Windows PC the file is a UTF-8 CSV with the structure:

Date;Time;ms;Tag1;Tag2;Tag3;Tag4;Tag5
01.05.2024;14:23:01;000;12.345;67.890;1;0;45.6
01.05.2024;14:23:02;000;12.367;67.910;1;0;45.6
...

The millisecond column provides sub-second resolution if the trigger cycle is below one second. Locale (DD.MM.YYYY vs MM/DD/YYYY) follows the panel's regional setting.

7. Configuring the Trend View (Live)

1. Add a Trend view object to the desired screen from the toolbox under Controls > Trend view or Controls > f(x) trend view for math overlays.
2. Insert five trend rows. For each row, set the source to the corresponding HMI tag (not the data log column - the live view reads directly from the HMI tag's value buffer).
3. Set the time axis range to a 10-minute window for live viewing. Enable the right-side toolbar with Properties > Toolbar > Show so operators can zoom in/out and scroll.
4. Set value-axis limits to the engineering range of the process to avoid auto-scaling drift.

8. Configuring the Historical Trend View (Archive Recall)

The historical trend view reads from the data log, not from the live tag buffer. This is the feature that satisfies "recall for any selected start and end time."

1. Add a second trend view on a dedicated screen called Archive.
2. Configure the trend rows to read from the data log columns (each row's Source is set to the data log column rather than an HMI tag).
3. Set the time axis source to the data log.
4. Add operator input fields ArchiveStartTime and ArchiveEndTime of type Date/Time. Wire each to the trend view's TimeRange_Start and TimeRange_End properties using a direct connection or a small script.
5. Add buttons for zoom in/out, scroll forward/backward, and "Jump to start."

For projects on a TP1200 or larger, the OnlineTrendControl and FunctionTrendControl are available in addition to the basic Trend view. These expose multi-axis ranges and curve coloring per row.

9. Configuring the Report Layout and Report Job

The report path provides a printable, time-bounded export of the trend data.

1. Open Report layouts under the HMI device, add a new layout ProcessReport.
2. Insert a Trend view report object onto the layout; bind it to the same data log as the historical trend view.
3. Open Report jobs and add a new job ProcessReportJob with these settings:
   • Trigger: Operator button (Bit-triggered by an HMI tag)
   • Storage path: \Storage Card SD\Reports\
   • Format: PDF (recommended) or printer
   • Time range: Bound to ArchiveStartTime and ArchiveEndTime tags

When the operator sets the start/end inputs and presses the Generate report button, the panel writes a PDF that contains the trend plots for the selected window.

10. CSV Export Procedure for External Print and Analysis

1. Stop the panel's data logging temporarily (toggle a runtime tag or stop the HMI via Control Panel > Stop Runtime).
2. Remove the SD card from the panel.
3. Insert the card into the engineering PC and copy the file \Logs\ProcessArchive_YYYYMMDD.csv to a Windows folder.
4. Open the CSV in Microsoft Excel, LibreOffice Calc, or import with pandas: pd.read_csv('ProcessArchive.csv', sep=';', parse_dates=[['Date','Time']]).
5. For repeated exports without removing the SD card, enable the FTP/SMB services on the panel and pull the CSV over the network. The FTP service is activated under Control Panel > Services.

An analogous save-trend workflow on AVEVA is described in the official AVEVA documentation: Save trend data to a .CSV file. Operators who are migrating from a Siemens Comfort Panel to AVEVA System Platform can reuse the same CSV ingest path on the SCADA side.

11. Storage Capacity Planning

Use the following formula to size the SD card before deployment:

rows_per_day = 86400 / cycle_seconds
bytes_per_row = 40 + sum(strlen(tag_value_as_string) + 1)  // approximate
mb_per_day = (rows_per_day * bytes_per_row) / (1024 * 1024)
usable_card_gb = 0.93 * card_size_gb                  // FAT32 overhead

Worked example for 5 Float tags at 1 s cycle:

rows_per_day  = 86400
bytes_per_row ~= 70  // '01.05.2024;14:23:01;000;12.345;67.890;1;0;45.6\r\n'
mb_per_day    = (86400 * 70) / 1048576 ~= 5.77 MB/day
32 GB card    = 29.8 GB usable
days_of_log   = 29800 / 5.77 ~= 5165 days  (14 years)

For the conservative 8 GB card referenced in the field report, the same calculation yields roughly 1,285 days (3.5 years) of continuous logging. Always reserve 20% free space on the SD card for wear leveling; never let the partition reach 100% capacity.

12. Verification and Commissioning Procedure

1. Download the project to the panel and start Runtime.
2. Confirm the data log path exists: open Control Panel > Storage; the SD card must show as OK with the configured free space.
3. Trigger the trend view to a fast cycle (e.g., 500 ms) and verify each of the five rows is plotting live values from the PLC.
4. Wait at least two trigger cycles and open the SD card on the engineering PC. Confirm ProcessArchive_YYYYMMDD.csv exists in \Logs\ and contains at least two rows.
5. Generate a report via the operator button. Confirm ProcessReport_YYYYMMDD_HHMMSS.pdf is present in \Reports\.
6. Open the historical trend view, set start and end times spanning the recorded window, and verify the curves display.
7. Export the CSV (via FTP or by removing the card), open in Excel, and plot Tag1 vs time to confirm the column structure.

13. Troubleshooting Matrix

14. Cross-Platform Reference Notes

The same five-tag data-logging requirement can be implemented on other HMI families with comparable capability. AutomationDirect's C-more HMI Line Trend Graph data-logging demonstration shows a similar 24-hour CSV-per-day pattern, where a new file is created at midnight. The CSV-per-day segmentation strategy is therefore a common industry convention and is the recommended default for the Siemens Comfort Panel implementation as well.

When the embedded panel becomes insufficient (multi-user access, central archiving, regulatory compliance requiring immutable storage), escalate the design to WinCC Runtime Professional on a PC, or to a SCADA such as AVEVA. The CSV export path described above is preserved across the escalation - only the storage backend changes.

15. FAQ