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4503

Weighting of the velocity pre-control not allowed

Beckhoff · TwinCAT 2 NC

What does 4503 mean?

The value specified for the percentage weighting of the velocity pre-control is not allowed, as it must be within the range [0.0 ... 1.0]. This parameter, typically preset to 1.0 (100%), influences the feedforward control of velocity. An invalid value can lead to poor motion tracking, instability, or overshoots/undershoots.

Common Causes

  • The velocity pre-control weighting parameter (e.g., P5-10, V-pre-control Weight) is configured outside the valid range of [0.0 ... 1.0].
  • Manual entry error: A value greater than 1.0 (e.g., 100) or less than 0.0 (e.g., -0.5) was entered via the HMI or software.
  • Scaling or unit conversion issue: A percentage value (e.g., 100%) was entered, but the parameter expects a fractional value (e.g., 1.0).
  • Configuration file corruption, causing the parameter to default to an invalid, out-of-range value.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    1. Access the velocity pre-control weighting parameter (e.g., P5-10) and set its value to be between 0.0 and 1.0 (e.g., 1.0 for 100% pre-control).

  2. 2

    2. Verify the input method (e.g., HMI, software) handles decimal values correctly and is not inadvertently converting input (e.g., 100 to 100.0).

  3. 3

    3. Review the system's tuning guidelines to determine the optimal pre-control weighting for the specific mechanical setup and application.

  4. 4

    4. Perform a parameter download from the configuration software to the controller to ensure the corrected value is properly applied.

  5. 5

    5. Monitor motor velocity response (e.g., using diagnostic D-01) after adjustment to ensure smooth motion and reduced tracking error.

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Verified technical data. Last updated: April 2026

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Source: Beckhoff TwinCAT 2 NC
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