Customizing PCS 7 System Messages and Hardware Diagnostic Text in WinCC Alarm Logging

In SIMATIC PCS 7 (including V8.1 SP1 and V9.x), system messages for hardware diagnostics (e.g., PROFIBUS/PROFINET node failures, rack faults) derive device names from HW Config but truncate identifiers to 16 characters in standard alarm views due to fixed message text formatting. To customize system message formatting across the project, edit the language-specific master template CSV files (e.g., LTMDatenEnu.CSV for English) located in C:\Program Files (x86)\Siemens\WinCC\bin, or concatenate extended strings in user diagnostic blocks.

Architecture of Automated System Message Generation in PCS 7

In SIMATIC PCS 7, process automation architectures automatically supervise thousands of distributed hardware components (distributed I/O racks, power supplies, interface modules, communication processors, and fieldbus slaves). When an ET 200M station or PROFIBUS-DP slave fails, the operating system triggers a System Message in WinCC Alarm Logging without requiring the engineer to author custom alarm logic.

This automation is managed by the Generate Module Drivers compiler wizard:
1. During CFC compilation, the wizard queries HW Config to extract the symbolic names, station numbers, and slot addresses of all configured hardware.
2. It instantiates diagnostic driver blocks (MOD_..., OB_..., RACK_...).
3. It maps hardware diagnostic events to standard System Message Numbers (e.g., Message 1000500: Rack failure, Message 1000501: Module removed).
4. In WinCC Alarm Logging, the station name from HW Config is passed dynamically into the message text via Associated Values (Process Values 1, 2, or 3).

Engineers frequently observe that while a slave in HW Config is named ET200M_WATER_TREATMENT_SKID_01 (29 characters), the alarm line displays only the first 16 characters, truncating the identifier. Furthermore, engineers seek to adjust the wording, alarm class, or priority of these system messages.

System Message Master Template and Language File Matrix

System messages are defined centrally within language-specific comma-separated value (CSV) baseline files in the WinCC binary installation folder:

File NameLanguage IDTarget LanguagePath LocationSystem PurposeLTMDatenEnu.CSV1033 (0x0409)English (United States)C:\Program Files (x86)\Siemens\WinCC\bin\Master template for English system messagesLTMDatenDeu.CSV1031 (0x0407)German (Standard)C:\Program Files (x86)\Siemens\WinCC\bin\Master template for German system messagesLTMDatenFra.CSV1036 (0x040C)French (Standard)C:\Program Files (x86)\Siemens\WinCC\bin\Master template for French system messagesLTMDatenChs.CSV2052 (0x0804)Chinese (Simplified)C:\Program Files (x86)\Siemens\WinCC\bin\Master template for Chinese system messages

Caution: Never edit LTMDaten files with Microsoft Excel; Excel alters delimiter formatting and corrupts the file.

Why Node Identifiers Are Truncated to 16 Characters in Alarm Logging

The truncation of fieldbus node names occurs due to the formatting string embedded within the system message definition:
* In LTMDatenEnu.CSV, the message text for a node failure is formatted as:
@1%16s@: Station Failure
* The string @1%16s@ instructs the WinCC Alarm Logging print parser to take Associated Value 1 (the node name string) and format it into a field width of strictly 16 characters (%16s).
* Any characters beyond the 16th character are truncated to ensure that the alarm text fits within standard PCS 7 alarm banner screen allocations without overlapping timestamp columns.

Step-by-Step Procedure to Edit LTMDaten.CSV Master Templates

To customize system message text, formatting, or expand the character width:

Back Up Original CSV Files:
* Navigate to:
C:\Program Files (x86)\Siemens\WinCC\bin\
* Create a backup copy of LTMDatenEnu.CSV (e.g., LTMDatenEnu_ORIGINAL.CSV).
Edit Master Template with Plain Text Editor (Notepad / Notepad++):
* Open LTMDatenEnu.CSV in a plain text editor (never Excel).
* Search for the specific message text or message number (e.g., search for %16s or Station Failure).
* Locate the formatting string:
csv 1000500,1033,"@1%16s@: Station Failure",...
* To prevent truncation, expand the string width to 24 characters:
csv 1000500,1033,"@1%24s@: Station Failure",...
* You can also prepend plant-specific identifiers or adjust the descriptive wording.
* Save the file with standard UTF-8 / ANSI encoding.
Synchronize Changes into WinCC Alarm Logging:
* Open the OS project in WinCC Explorer.
* Open Alarm Logging.
* In Alarm Logging, select Tools > Update System Messages (or toggle the project runtime language back and forth once to force a reload from the updated CSV template).
* Verify that the updated message definitions appear in the system messages list.

Verification

Verify customized system message rendering:
1. In HW Config, configure a slave with a 24-character name (e.g., ET200M_WATER_TREAT_01).
2. Disconnect the PROFIBUS/PROFINET cable from the slave to induce a simulated station failure.
3. Open WinCC Alarm Logging in Runtime:
4. Confirm that the incoming alarm displays the complete 24-character node identifier without truncation, reflecting the updated formatting string from LTMDatenEnu.CSV.

Limitations and Operational Precautions

Installing WinCC updates, service packs, or PCS 7 hotfixes may replace LTMDatenEnu.CSV with default Siemens catalog files; always retain an external backup of your customized CSV templates.
Expanding message string widths can cause text to clip on low-resolution operator screens; verify that WinCC AlarmControl column widths are expanded to accommodate longer strings.
Do not alter the numeric Message Number column in LTMDaten<Lang>.CSV; modifying system message IDs breaks internal operating system diagnostic bindings.

Engineer FAQ

Can I customize system messages on a per-project basis rather than globally?

Yes. Once system messages are loaded into the OS project's Alarm Logging database, you can edit individual system messages directly in the WinCC Alarm Logging editor; however, running 'Update System Messages' will revert them to the master CSV templates.

Why does Excel corrupt the LTMDaten CSV file?

Microsoft Excel automatically converts string columns, strips leading zeroes, and replaces standard comma delimiters with local regional semicolons, causing the WinCC parser to reject the file.