The message “wait: Aux. fct. ackn. miss.” appeared after a battery-related memory loss and project restoration on a three-axis SINUMERIK 840D system. The axes would not move in automatic mode, although they did move in JOG. This combination narrows the fault to an automatic-cycle condition or machine-specific auxiliary-function handshake rather than proving an axis-drive failure.
Interpret the observed machine state
| Observation | Engineering implication |
|---|---|
| Axes move in JOG | Basic manual motion is available; investigate conditions used specifically by the automatic sequence. |
| Automatic mode does not produce axis motion | The program may be waiting before reaching or completing its motion command. |
| “Auxiliary function acknowledge missing” blinks | An auxiliary request appears to be waiting for a required acknowledgement or completion condition. |
| Channel active/interrupted and program running/stopped indications change rapidly | Capture the exact program line and machine state when the indications change; the messages alone do not identify the missing condition. |
| No alarm number was recorded | Do not diagnose from the abbreviated text alone. Record any associated alarm number and full message text. |
Focus on machine-specific auxiliary functions
The available evidence points to a missing automatic-mode condition, but it does not identify the responsible signal or configuration. Tool-change commands, an automatic tool changer, or a turret are relevant only if the program stops when invoking that equipment. These applications and their acknowledgement logic may be supplied by the machine builder rather than defined by a universal SINUMERIK setting.
Do not remove a tool command merely to suppress the wait message. First establish which program instruction requests the auxiliary action and whether the corresponding mechanism initializes, completes its sequence, and returns the condition expected by the restored control project.
Run a controlled diagnostic sequence
- Confirm and document that each axis moves in JOG, then verify whether the axes are referenced.
- Test the permitted axis and spindle functions in MDI. Record which functions work and which remain blocked.
- Review the part program and identify the exact line active when “Aux. fct. ackn. miss.” appears.
- If that line calls a tool change or another auxiliary function, check whether the machine has an ATC or turret and whether that mechanism is initialized and operating correctly.
- Record the complete alarm text and alarm number, if one exists. Also capture the active program line and the channel/program status at the same instant.
- Compare the observed failure point with the automatic-mode conditions implemented in the restored machine project. Escalate unresolved machine-sequence logic to the machine builder or Siemens support.
Define the escalation package
Provide support with the SINUMERIK 840D identification, the fact that memory loss followed a late battery change, the restored backup identity, the affected channel, the exact NC program line, complete alarm text and number, reference status, JOG and MDI results, and whether an ATC or turret is fitted. This separates a control alarm from a builder-specific interlock or auxiliary acknowledgement without guessing at an undocumented signal.
FAQ
Why does a SINUMERIK 840D move in JOG but not automatic mode?
The evidence indicates that manual motion can remain available while the automatic program waits for a missing condition. Check axis referencing, the active program line, and any auxiliary mechanism invoked at that line.
What does “Aux. fct. ackn. miss.” mean on an 840D?
It indicates that an auxiliary function is waiting for an acknowledgement. The abbreviated text does not identify the source, so capture the full message, alarm number, active program line, and associated machine action.
Can removing the tool-change command clear the auxiliary acknowledgement message?
Removing the command may bypass the point where the wait appears, but it does not establish or correct the missing acknowledgement. Diagnose the ATC or turret initialization and the machine-builder sequence associated with that command.