16761

In Siemens HMI or Operate menu, navigate to Diagnostics > Machine Data > Axis/Spindle Assignment (MD 20050-20059 range). Verify that the axis letter called in the NC program matches the channel currently executing.

Do not modify machine data during active machining cycles.

Cross-reference the NC program block with the actual axis configuration. For example, if block contains 'G01 X100' but X-axis is assigned to Channel 2 via MD 20050 and you're running in Channel 1, reprogramming is required or axis reassignment must occur.

If axis reassignment is required, modify MD 20050 (AxisAssignment) in the NCK Parameters menu. Document the change in machine setup records. Perform a full machine initialization (Power On → Reference Run) to activate changes.

Incorrect axis reassignment can cause collision or loss of synchronization in multi-channel applications.

Test with a simple NC program (e.g., G01 X10 F100) on the corrected channel to confirm alarm 16761 no longer occurs.

Access the Diagnostics > PLC > Inputs/Outputs menu (or use Service Pack diagnostics). Check DB10 variables and axis enable/inhibit flags. Look for signals like 'axis_inhibit_X', 'channel_lock', or equivalent naming in your machine configuration.

PLC status flags are read-only in Diagnostics mode; do not attempt modification from operator interface.

Review the PLC source code (STEP 7 or TIA Portal) for any M-function or conditional logic that disables axis access. Search for statements like 'Axis.Enable := FALSE' or 'Channel[1].Lock := TRUE' linked to the current channel or axis.

Verify machine safety interlocks are satisfied (door closed, emergency stop released, mode selector in AUTO/JOG). Many SINUMERIK systems lock axes until safety conditions clear. Check physical signals via Diagnostics > I/O > Digital Inputs.

Never bypass safety interlocks; coordinate with machine builder or qualified technician.

If PLC logic is blocking axis access incorrectly, correct the PLC program logic, compile, and download to the PLC. Reset the NCK via Diagnostics > System > Warm Restart or power cycle the control.

In the NC program, identify the spindle reference (typically S-word or M03/M04 command). Navigate to Diagnostics > Machine Data > MD 20051 (SpindleAssignment) to confirm spindle assignment matches the active channel.

If running a multi-channel program (e.g., simultaneous Channel 1 and Channel 2 machining), verify that only one channel at a time issues S or M03/M04/M05 commands. Use WAITFOR or synchronization logic to serialize spindle access between channels if both require spindle control.

Uncoordinated spindle commands from multiple channels will consistently trigger 16761.

Check MD 25200 (SpindleMode) and spindle control parameters to ensure the active spindle queue is assigned to the correct channel. Review SINUMERIK documentation for spindle synchronization syntax (e.g., WAITFOR AXIS/SPINDLE) if multi-channel spindle sharing is required.