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Fanuc alarm PS0126: ILLEGAL LOOP NUMBER

PS alarm (program/operation) · Fanuc 0i-D

What it means

The DO and END numbers in a custom macro do not pair correctly or fall outside the valid range 1 to 3. Loop identifiers must match pairwise.

Likely causes

  • DO/END numbers mismatched (e.g. DO1 ... END2)
  • Loop number 4 or higher used
  • Unbalanced nesting of numbered loops

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