Troubleshooting Missing STEP 7 Text Database Descriptions and Hex Diagnostic Events in PCS 7

To troubleshoot missing STEP 7 text database descriptions in the SIMATIC PCS 7 diagnostic buffer, update your STEP 7 text database files by installing the latest Hardware Support Packages (HSP) and STEP 7 updates on the Engineering Station, or decode the raw event hexadecimal parameters manually. When the diagnostic buffer shows 'No Entry in text database', the raw 16-bit Event ID and Additional Information words provide the exact operating system fault code. Cross-referencing these hex values with the SIMATIC S7-400 System and Standard Functions Reference Manual identifies the originating subsystem, whether peripheral I/O, communication, or user program logic.

Executive Summary

In SIMATIC PCS 7 maintenance and operations, the CPU diagnostic buffer is the primary window into controller health. When unfamiliar hexadecimal codes appear accompanied by the disclaimer 'No Entry in text database. Hexadecimal values will be displayed', engineers often struggle to determine if an urgent plant intervention is required. This condition arises when the Engineering Station's STEP 7 installation lacks the NLS (National Language Support) text definitions for specific firmware builds or communication processor events. This article provides a comprehensive methodology for decoding raw diagnostic events, explains how to restore missing text databases, and details diagnostic buffer log analysis.

Architectural and System Mechanics

The STEP 7 Diagnostic Text Database architecture:

Text Database Files: Located within the STEP 7 installation folder (typically C:/Program Files (x86)/Siemens/Step7/S7DATA/S7TEXT/), these indexed files map 16-bit hex Event IDs to multilingual descriptive text.
Structure of Hex Diagnostic Records:
Event ID: 2 bytes. The high nibble defines the event class (e.g., 1 = Start/Stop events, 2 = Asynchronous errors, 3 = Synchronous errors, A/B = Communication/CP events).
OB Number: Identifies the Organization Block triggered by the event (e.g., OB1, OB82, OB85, OB86).
PK (Priority Class): Specifies the execution priority of the triggered interrupt.
DatID: Differentiates incoming (error occurred) vs outgoing (error cleared) transitions.
Additional Info 1, 2, 3: Context-specific registers containing error codes, module addresses, or channel numbers.

Step-by-Step Engineering and Implementation Procedure

Step 1: Export and Isolate the Hexadecimal Record

Open Module Information in STEP 7, select the Diagnostic Buffer tab, check 'Hexadecimal view', and click 'Save As...'. Note the exact Event ID, OB, PK, DatID, and Additional Info fields.

Step 2: Decode the Event Class and Originating Subsystem

Evaluate the high nibble of the Event ID:
- 16#1xxx: Operating mode transitions (STOP, RUN, memory reset).
- 16#2xxx: Errors in the operating system or hardware faults (power supply, backup battery).
- 16#3xxx: Program execution errors (addressing errors, area length violations).
- 16#4xxx: Module and rack faults (distributed I/O station return, rack failure).
- 16#Axxx / 16#Bxxx: Communication processor and S7 connection diagnostic events.

Step 3: Map Additional Info to Siemens Status Codes

If the event belongs to Class A or B, look up Additional Info 1 in the S7 System Software manual under 'Communication SFC/SFB Status Codes'. For example, code 80C3 identifies resource bottlenecks, while 8090 signifies invalid connection IDs.

Step 4: Reinstall or Update STEP 7 Hardware Support Packages

Close SIMATIC Manager.
Open HW Config, navigate to 'Options' -> 'Install Hardware Updates'.
Download and install all relevant updates for your CPU and communication processor MLFBs.
Reopen the diagnostic buffer; verified events will now display clear text explanations instead of the missing database message.

Verification

To verify diagnostic restoration:
1. Reopen Module Information -> Diagnostic Buffer on the target CPU.
2. Verify that previously unresolved events now display descriptive titles and localized explanatory text.
3. Confirm that the 'Help on Event' button functions properly, opening the exact Siemens reference manual page for that diagnostic event.

Limitations and Operational Precautions

Operational precautions:
- Some custom OEM blocks and third-party DP/PN communication modules deliberately generate user-defined diagnostic entries (16#8xxx or 16#9xxx) that will never exist in the standard Siemens text database.
- Updating HSPs on the Engineering Station updates display text only; it does not change the running controller firmware unless a firmware update is explicitly performed.

Engineer FAQ

Q: Can missing text database entries damage the controller?

A: No. The text database resides entirely on the Engineering Station PC and has zero impact on CPU execution or real-time control.

Q: Why does 'Help on Event' say 'No help available'?

A: This occurs when the corresponding event ID has no mapped HTML/text help file in the installed STEP 7 documentation language.

Q: Are diagnostic buffer records preserved across a CPU power cycle?

A: Yes, S7-400 CPUs retain diagnostic buffer entries in non-volatile memory or battery-backed RAM.

Q: How many events does an S7-400 diagnostic buffer hold?

A: Depending on the CPU model, the diagnostic buffer holds between 120 and 3200 entries (configurable in CPU properties).

Q: Can WinCC Alarm Logging receive these hex events?

A: System events compiled via AS-OS engineering (such as module faults) generate WinCC alarms automatically, but internal OS debug events remain in the CPU buffer.

Technical References

Related Tags

Diagnostic Buffer, Hex Event Codes, STEP 7 HSP, Hardware Diagnostics, S7-400 Troubleshooting

`S7-400 Troubleshooting`

20 respuestas

Troubleshooting Missing STEP 7 Text Database Descriptions and Hex Diagnostic Events in PCS 7