Siemens SINUMERIK codes
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Siemens SINUMERIK Controller

Servo/Axis · Basic · 10-20 minutes

Alarm 16925

Siemens 840D 16925 - Channel program control: action <ALNX> not allowed in the

The action has been refused since a mode or sub-mode change (change to automatic mode, MDI, JOG, overstoring, digitizing, etc.) is taking place. Example: This alarm message is output if the Start key is pressed during a mode or sub-mode change from, for example, automatic to MDI, before the NCK has

Siemens SINUMERIKServo/AxisBasic10-20 minutes

16925

Siemens 840D 16925 - Channel program control: action <ALNX> not allowed in the

Channel program control: action <ALNX> not allowed in the

The action has been refused since a mode or sub-mode change (change to automatic mode, MDI, JOG, overstoring, digitizing, etc.) is taking place. Example: This alarm message is output if the Start key is pressed during a mode or sub-mode change from, for example, automatic to MDI, before the NCK has

Safety

  • Refer to Siemens documentation
  • Ensure qualified technician performs repairs

Common Causes

  • User pressed Start or other control action while mode transition (automatic to MDI, JOG, etc.) was in progress
  • Rapid mode/sub-mode switching without allowing NCK to complete state transition
  • Control panel input during system initialization or mode change handshake
  • Interfering external program commands during manual mode selection
  • HMI or PLC sending conflicting commands during mode change cycle

Troubleshooting Steps

  1. 1Acknowledge alarm and wait 2-3 seconds before attempting next control action to allow NCK mode transition to complete
  2. 2Verify operator is not pressing multiple control buttons simultaneously; ensure sequential button presses with pause between actions
  3. 3Check HMI panel for stuck buttons or contact issues causing repeated input signals during mode changes
  4. 4Review PLC program or external automation sending commands to ensure no overlapping mode change requests are queued
  5. 5Monitor NCK state transitions in Diagnostics menu; confirm mode change completes fully before issuing new actions like Start or Feed Hold

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