C135 PCS 7 (PCS7)
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Switching Between AnaTxt and TextOP Limit Labels on APL Analog Faceplates

Switching Between AnaTxt and TextOP Limit Labels on APL Analog Faceplates

APL analog faceplates switch from displaying descriptive limit texts (AnaTxt: 'High Warning') to abbreviated operational codes (TextOP: 'HH', 'H', 'L', 'LL') when the PCS 7 Message System is adapted to priority-based alarming in SIMATIC Manager. The underlying C-script 'APL_GetAlarmLimitText' invokes 'CCACDIsPriorityBasedEnabled()'; if priority-based alarming is enabled in the WinCC database, TextOP is permanently enforced. Once adapted, this setting cannot be globally reverted via project toggles; restoring descriptive labels requires modifying the WinCC Text Library or editing standard faceplate text templates.

Table of Contents

Mechanics of APL Alarm Limit Texts and the CCACD Function

In SIMATIC PCS 7 Advanced Process Library (APL), analog monitoring blocks (MonAnL, PIDConL) display operational alarm limits within the view picture @PG_MonAnL_Limit.pdl.

The textual labels assigned to high and low limits are retrieved dynamically via the WinCC C-function APL_GetAlarmLimitText:
* AnaTxt (Legacy / Descriptive Mode): Returns long descriptive text strings extracted from the WinCC Text Library, such as "High Alarm", "High Warning", "Low Warning", and "Low Alarm".
* TextOP (Priority / Abbreviated Mode): Returns standardized abbreviated technical codes: HH (High-High Alarm), H (High Warning), L (Low Warning), and LL (Low-Low Alarm).

Inside APL_GetAlarmLimitText, the script queries CCACDIsPriorityBasedEnabled(). This internal API checks whether the active WinCC project has been configured for the modern PCS 7 Priority-Based Alarm System compliant with ISA-18.2. If active, the function bypasses AnaTxt and returns the TextOP string array.

Adapting the PCS 7 Message System and Irreversible Conversions

The transition from AnaTxt to TextOP occurs when an engineer executes the message adaptation wizard in SIMATIC Manager:
1. In SIMATIC Manager, selecting Options -> Plant Configuration -> Message System triggers the message configuration wizard.
2. Enabling Standard PCS 7 Message System with Priority rewrites the internal message classes, priorities (1 to 16), and message attributes across the entire multiproject database.
3. Irreversibility: Once the message system is adapted and compiled to WinCC, the project database flags priority mode as active. There is no automated "Undo" or revert check box to return to the legacy AnaTxt scheme.

To restore descriptive limit texts when priority mode is active:
* Option 1: Modify WinCC Text Library: Open Text Library in WinCC Configuration Studio. Locate the text IDs assigned to TextOP (e.g., HH, H) and replace the string values with custom descriptive phrases ("High Warning").
* Option 2: Faceplate Graphic Template Modification: In WinCC Graphics Designer, customize @PG_MonAnL_Limit.pdl (saved without the @ prefix in user projects) to bypass APL_GetAlarmLimitText and read static text labels.

Verification

  • In WinCC Runtime, open the faceplate for an analog monitoring block (MonAnL).
  • Navigate to the Limit view.
  • Confirm that limit rows display the intended labels (e.g., High Alarm vs HH) adjacent to their respective numerical setpoint input fields.
  • Trigger an analog alarm limit violation and confirm that incoming messages in the Alarm Control reflect matching alarm classes and priority colors.

Limitations and Operational Precautions

  • Modifying @ system screens directly in GraCS is unsupported because running the OS Project Editor overwrites them. Always customize via the WinCC Text Library whenever possible.
  • International multi-language plants must update both English and regional language columns in the Text Library to maintain consistent operator displays.
  • ISA-18.2 recommends abbreviated limit designations (HH, H) in high-performance HMI displays to reduce clutter and accelerate operator response.

Engineer FAQ

  • What does CCACD stand for in WinCC?
    CCACD refers to the Central Component Alarm Configuration Database, the internal WinCC subsystem responsible for managing alarm classes, types, and priority routing.
  • Why did Siemens shift from AnaTxt to TextOP?
    Modern process safety standards (ISA-18.2, EEMUA 191) favor concise, standardized alarm identifiers (HH, H, L, LL) over multi-word sentences to improve operator cognitive processing during alarm floods.
  • Can I keep priority-based alarms while using descriptive limit names?
    Yes. By editing the TextOP string entries directly inside the WinCC Text Library, you retain full 16-level alarm prioritization while displaying descriptive words on faceplates.

Technical References

  • SIMATIC PCS 7 Advanced Process Library (APL) Function Manual (A5E43360408-AA).
  • SIMATIC PCS 7 OS Process Control System; Message System Architecture Manual.
  • ANSI/ISA-18.2: Management of Alarm Systems for the Process Industries.

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Related Tags

PCS 7, APL, WinCC, MonAnL, Alarm Limits, Text Library, AnaTxt, TextOP

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