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ErrorLib — Industrial Fault Code Library

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7

Length Error

Allen-Bradley · MicroLogix 1400 Programmable Controllers

What does 7 mean?

The total output pulses to be generated (TOP) for the PTOX instruction are less than zero. This error faults the controller and indicates an invalid motion parameter, as pulse counts must be non-negative. It can be cleared by logic within the User Fault Routine.

Common Causes

  • Total output pulses (TOP) parameter set to a negative value.
  • Incorrect calculation or direct input of a negative TOP parameter in the PTOX instruction.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Adjust the total output pulses (TOP) value in the PTOX instruction to be zero or a positive value.

  2. 2

    Review the program logic that writes to the TOP parameter to ensure it calculates and sets a valid pulse count.

  3. 3

    Clear the fault using the User Fault Routine or by cycling power after correcting the TOP value.

Browse all codes in this manual (60)
Verified technical data. Last updated: April 2026

Related Faults

-1Output Error-2Overlap Error-3Undefined Accel/Decel
Source: Allen-Bradley MicroLogix 1400 Programmable Controllers
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