PLC Function Block Reports CommandAborted? Do Not Treat It as Done
An interrupted motion command is not the same as a completed move. If a sequence advances after another command replaces its move, inspect CommandAborted, Error, Busy, and Done according to the block contract.
PLCopen reference; verify vendor-specific implementation and permitted machine tests.
What is happening?
PLCopen motion blocks define status outputs for distinct outcomes. Buffering and replacement behavior depend on the block, mode, and vendor implementation. A false Busy signal alone does not establish successful completion.
Check these five things
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Identify the exact motion block and configured buffering mode.
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Trace every command that can target the same axis.
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Record the complete outcome status and error information.
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Define handling for completion, failure, and replacement separately.
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Test competing commands in a suitable motion simulation.
Worked example
A teaching move is replaced by a new accepted command. Its Busy output falls and CommandAborted indicates interruption. A sequence using only NOT Busy advances incorrectly, while one following the documented outcome status can select the required recovery or replacement path.
Quick diagnostic reference
| Outcome | Meaning |
|---|---|
| Done | Specified completion |
| Error | Reported failure |
| CommandAborted | Interrupted or replaced as defined |
The mistake to avoid
Do not force the done flag or ignore aborted status to keep the sequence moving. Determine which controller legitimately owns the axis command.
How to verify the fix
Verify normal completion, command replacement, and error cases with the full status trace. Confirm product handling proceeds only on the approved outcome.
Field-work boundary: These are educational diagnostic guides. Use the exact equipment manuals and approved site procedures. Electrical testing and machinery changes belong to qualified, authorized personnel; control hazardous energy and validate affected functions before release.
Technical reference
PLCopen: Motion Control function blocks. The examples and diagnostic tables above are original teaching material; they do not replace the product manual.