29033

Check the PLC program logic in the axis control section. Verify that the axis movement (MOVE_AXIS command or FC18 call) includes proper end-of-movement confirmation before issuing subsequent axis allocation commands.

Do not bypass the end-of-stroke check; this protects against collision and loss of position data.

Examine the DB_AXIS structure in the PLC data block. Confirm that isActive flag is being monitored and that the next MOVE_AXIS or axis change command is only issued after isActive returns to FALSE.

Review MD32100 (MaxAxisVelocity) and MD32110 (MaxAxisAcceleration) for the affected axis to ensure movement parameters are reasonable and not causing extended settling times.

Use the SINUMERIK 840D Service screen (Diagnostics → Axis State) to monitor axis motion completion in real-time during the problematic PLC sequence.

Verify FC18 is instantiated with correct parameters in the PLC axis control OB. Check that the END_OF_STROKE input is wired to a real hardware signal (encoder feedback, drive status, or limit switch) that reliably indicates axis movement completion.

Missing END_OF_STROKE feedback will cause the axis to hang in ACTIVE state permanently.

Inspect the MOVE axis command in the PLC: confirm DISTANCE and VELOCITY parameters are set, and that a valid START pulse is issued. Verify the PLC does not issue a second MOVE command before the first axis reaches end position.

Check hardware signal chain: drive feedback (READY signal from servo drive/stepper), encoder tick count validation, and limit switch status. Use NCK Diagnostics menu (Axis → Signals) to confirm END_OF_STROKE signal transitions from 0 to 1 when axis stops.

Review the axis-to-channel mapping in NCK Configuration → Channels. Check MD35000 (AxisToChannelMapping) and verify that the axis in question is not statically allocated to a single channel if dynamic reassignment is required by the PLC.

Static axis allocation (via MD35000) prevents PLC-side reassignment; use dynamic allocation if multi-channel operation is needed.

Examine the PLC logic for axis neutralization sequence. Before reassigning an axis to a new channel, explicitly call FC18 or equivalent to set the axis to NEUTRAL state (isNeutral = TRUE). Only after neutral state confirmation should a new channel assignment command be issued.

Use NCK menu Diagnostics → Axis Allocation to observe real-time axis channel ownership. Verify that when alarm 29033 fires, the axis is not in ACTIVE state in its current channel during the reassignment attempt.