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How to Resolve 'Parameter Assignment Not Successful' Faceplate Warnings in Migrated PCS 7 V8.1

How to Resolve 'Parameter Assignment Not Successful' Faceplate Warnings in Migrated PCS 7 V8.1

In SIMATIC PCS 7 V8.1, faceplates of migrated Advanced Process Library (APL) drive blocks (such as MotL, VlvAnL, and VlvL) displaying warning texts like 'Parameter assignment not successful' or 'Cir Parameter ass...' are caused by outdated faceplate picture files (@PG_*.pdl) in the OS project or invalid parameter bounds on newly introduced block inputs in the AS. When projects are migrated across major versions, legacy faceplate scripts fail to evaluate newly added status and error words (ErrorNum / ParaErr). The issue is resolved by running OS Project Editor to update all APL faceplate templates in the OS GraCS directory and verifying parameter ranges (e.g., Scale.High > Scale.Low) in CFC.

Table of Contents

APL Parameter Assignment Error Architecture

The SIMATIC PCS 7 Advanced Process Library (APL) incorporates rigorous automated validation of engineering parameters configured on technological blocks (including MotL, MotRevL, VlvL, and VlvAnL).

Within each block's algorithmic code, the controller continuously evaluates parameter sanity:
* Verifying that scale limits are logically ordered (Scale.High > Scale.Low).
* Verifying that monitoring times are strictly positive (MonTiDynamic > 0, MonTiStatic > 0).
* Verifying that control pulses and transition timers are within valid bounds.

If an invalid parameter combination is detected, the block asserts an internal error flag:
* ErrorNum: Error Number output parameter (integer code identifying the configuration fault).
* ParaErr: Parameter Assignment Error boolean flag.

On the WinCC Operator Station, standard APL faceplates parse ErrorNum and ParaErr to display descriptive operator messages in the faceplate header banner and preview view.

Root Cause Analysis for Garbled Faceplate Text After Migration

When a PCS 7 project is migrated from an older release (e.g., PCS 7 V7.1 or V8.0) to PCS 7 V8.1, opening drive block faceplates frequently results in truncated or garbled warning texts such as:
'Parameter not assign successful' or 'Cir Parameter ass...'

Primary Root Causes

  1. Outdated Faceplate PDL Files in the OS Project: When a project is imported into PCS 7 V8.1, the WinCC project's graphics directory (GraCS) still contains older @PG_*.pdl and @PL_*.pdl faceplate files from the previous library version. The V8.1 AS block sends an expanded 32-bit status word structure, but the legacy V7.x/V8.0 faceplate script expects an older bit offset, misinterpreting normal operating flags as parameter assignment faults.
  2. Newly Introduced Block Inputs with Zero Defaults: Upgrading block types from older APL versions introduces new technological parameters. If an upgraded instance has uninitialized inputs (e.g., Scale.High and Scale.Low both defaulting to 0.0, or SafePos set to an illegal enum value), the AS block triggers ErrorNum = 51 (invalid scale configuration), asserting the parameter fault.
  3. Missing or Corrupted OS Project Editor Execution: If the OS Project Editor was not run after the migration, the standard system scripts (apdefap.h, APL_*.fct) and Text Library translations remain out of synchronization with the installed APL version.

Step-by-Step Remediation Procedure

To resolve parameter assignment warnings and restore proper faceplate display:

Step 1: Verify Technological Parameter Ranges in CFC

  1. Open the CFC chart containing the affected drive block (MotL, VlvAnL, etc.).
  2. Inspect the block's input parameters online:
    * Scale Limits: If using analog feedback or setpoints, ensure Scale.High > Scale.Low (e.g., Scale.High = 100.0, Scale.Low = 0.0). Setting both to 0.0 triggers an immediate parameter assignment fault.
    * Monitoring Times: Ensure MonTiDynamic and MonTiStatic are > 0.0 if monitoring is enabled (Monitor = 1).
    * Pulse Durations: Verify PulseWidth > 0.0.
  3. Check the block output ErrorNum:
    * If ErrorNum = 0, the AS block is logically sound; the error originates entirely from an outdated OS faceplate script.

Step 2: Update WinCC Faceplate Templates via OS Project Editor

  1. In WinCC Explorer on the OS Server (or ES), open OS Project Editor.
  2. Navigate to the Basic Data tab.
  3. In the file list, ensure that all @PG_*.pdl, @PL_*.pdl, and @PCS7_*.pdl files are marked with 'Update' (or select the radio button 'All project pictures with factory settings').
  4. Click OK.
  5. OS Project Editor copies the fresh, certified PCS 7 V8.1 APL faceplate templates from the Siemens installation folder (Siemens\WinCC\Options\Pdl\Base_Data_Pool) into the project's GraCS directory, overwriting legacy files.

Step 3: Update Text Library and Compile OS

  1. In SIMATIC Manager, right-click the OS project and select Compile.
  2. Select Entire OS (or Changes only with 'Tags and messages' enabled).
  3. The compiler synchronizes the Text Library with all official V8.1 multilingual error strings.
  4. Download the updated OS project to the operator stations.

APL Drive Block Error Codes and Faceplate Indicators

The following table outlines common ErrorNum values on APL drive blocks and their corrective actions:

ErrorNum CodeMeaning / Configuration FaultAffected BlocksResolution Action0No Error (Normal operation)All APL BlocksIf faceplate displays error, update @PG_*.pdl51Invalid Scale (Scale.High <= Scale.Low)VlvAnL, MotSpdCLSet Scale.High strictly greater than Scale.Low52Invalid Monitoring Time (MonTiDynamic <= 0)MotL, VlvLSet positive monitoring duration in seconds53Invalid Safe Position ConfigurationVlvL, VlvAnLSet SafePos to valid state (0 or 1)61Feedback Channel Configuration ErrorMotL, MotRevLCheck feedback interconnections (FbkRun, FbkOpen)

Ensuring valid parameters in CFC clears ErrorNum to 0 and extinguishes the faceplate warning.

Verification

To verify that the faceplate error has been permanently cleared:
1. In WinCC Runtime, open the faceplate of the previously affected drive block (MotL, VlvAnL).
2. Verify that the warning string 'Parameter assignment not successful' has completely disappeared from the header banner and preview view.
3. Verify that operating modes (Manual, Automatic, Out of Service) can be selected without restriction.
4. In CFC Editor, check the block output ErrorNum online and confirm it reads 0.
5. Open multiple other migrated blocks across different areas to ensure system-wide template alignment.

Limitations and Operational Precautions

  • Running OS Project Editor with 'All project pictures with factory settings' overwrites customized system templates; if custom modifications were made to @screen.pdl or @Overview1.pdl, back them up prior to running the editor.
  • Parameter assignment errors prevent automatic operations; while ErrorNum > 0, the block typically forces safe position or locks automatic commands.
  • If custom language fonts are installed on the OS PC, ensure Windows Regional Settings match the project compilation language to avoid character truncation in faceplate banners.
  • Always recompile the OS after updating block types or running OS Project Editor to ensure tag alignment.

Engineer FAQ

Why does the faceplate show an error if ErrorNum in CFC is 0?

If ErrorNum is 0 in the controller but the faceplate shows 'Parameter assignment not successful', the OS graphics folder contains outdated faceplate PDL files from a previous PCS 7 version that misinterpret the V8.1 status word.

How do I update faceplate PDLs without losing custom process mimic diagrams?

OS Project Editor only updates system templates prefixed with @ (such as @PG_*.pdl, @Overview1.pdl). User process pictures (without @ prefix) are completely untouched.

What causes ErrorNum = 51 on a VlvAnL valve block?

ErrorNum = 51 indicates that the analog scale configuration is invalid, specifically that Scale.High is less than or equal to Scale.Low.

Technical References

Related Articles

Related Tags

  • APL_Faceplates
  • Parameter_Assignment
  • ErrorNum
  • OS_Project_Editor
  • PCS7_V8_1
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