Pause, Stop, and Abort Share One Button Path? Review Recovery Behavior
Different interruption commands can require different recovery paths. If every event simply clears a run bit, the program may lose the information needed to resume, reset, or terminate work correctly.
PackML provides a reference model; the specific machine defines permitted behavior.
What is happening?
State models such as PackML distinguish operational states and transitions. Their meaning must be mapped to the machine requirements. A process hold, ordinary stop, and fault abort should not be treated as interchangeable merely because motion ceases.
Check these five things
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Define each supported interruption in the functional specification.
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Record which work and state are preserved or discarded.
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Trace commands through intermediate and settled states.
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Specify who authorizes recovery and under which conditions.
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Test interruptions at each meaningful process phase.
Worked example
A teaching filling process may preserve progress during a controlled hold but reject the container after an abort. Routing both events to the same restart branch can either repeat material addition or resume an invalid product. The correct behavior depends on the process specification.
Quick diagnostic reference
| Question | Record |
|---|---|
| Progress preserved? | Resume eligibility |
| Product valid? | Disposition |
| Reset required? | Recovery authorization |
The mistake to avoid
A state-model label does not establish machine safety. Physical stopping and energy-control functions require the validated design and must remain distinct from this software discussion.
How to verify the fix
Verify product disposition, state retention, and permitted restart for each interruption. Keep the accepted transition map available to operators and maintenance.
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
OPC Foundation: PackML state representation. The examples and diagnostic tables above are original teaching material; they do not replace the product manual.