E2

Severe error

ABB · AC500

What does E2 mean?

This severe error signifies that while the operating system itself is functioning, the error-free processing of the user program cannot be guaranteed. A common cause is a checksum error detected in the user Flash memory, which impacts program execution stability. Unresolved, this can lead to incorrect program logic, unexpected machine behavior, or intermittent operational failures without crashing the entire OS.

Common Causes

  • User program error preventing error-free data processing.
  • Data corruption within the user application logic.
  • Runtime exception in the user-defined task.

Repair Steps & Checklist

Click steps to track your progress.

  1. 1

    Review user program for division-by-zero operations in calculations.

  2. 2

    Examine memory allocation within the user program for potential overflows.

  3. 3

    Step through user program logic using debugging tools to identify incorrect variable assignments.

  4. 4

    Verify all input data used by the user program is within expected ranges.

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Verified technical data. Last updated: March 2026

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