Siemens SINUMERIK codes
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Siemens SINUMERIK Controller

Program/G-code · Intermediate · 20-45 minutes

Alarm 16020

Siemens 16020 - Repositioning in block is not possible

SINUMERIK alarm 16020 occurs when the spindle fails to reach the programmed orientation angle within the monitoring time defined in MD35110 (SPIND_POSITIONING_TIME). The NC expects position feedback confirmation from the spindle drive after issuing M19 or automatic tool change orientation commands.

Siemens SINUMERIKProgram/G-codeIntermediate20-45 minutes

16020

Siemens 16020 - Repositioning in block is not possible

Repositioning in block is not possible

Programming or operator action incorrect: Repositioning via REPOS command is only possible in an asynchronous subprogram (interrupt routine). If the REPOS command was programmed, e.g. in the main program or in a cycle, part program execution is aborted with alarm 16020. In addition, the alarm is output in the following situations: - Access to $AC_RETPOINT (repositioning point) outside an ASUP (e.g. in the main program) - An axis to be repositioned was a oscillating axis with sychronous infeed (OSCILL) in the interrupted block and is now in a state that does not allow it to be traversed as a oscillating axis. Remedy: Change the axis to "neutral axis" state before repositioning with WAITP. - An axis to be repositioned was an infeed axis for a oscillating axis in the interrupted block; now it can no longer be traversed as one. Remedy: Change the axis back to "POS axis" state before repositioning Control reaction: Interpreter stop NC Start disable in this channel. Interface signals are set. Alarm display.

Root Cause Summary

SINUMERIK alarm 16020 occurs when the spindle fails to reach the programmed orientation angle within the monitoring time defined in MD35110 (SPIND_POSITIONING_TIME). The NC expects position feedback confirmation from the spindle drive after issuing M19 or automatic tool change orientation commands.

Safety

  • Only qualified personnel should diagnose and clear control alarms; follow the machine builder's safety procedures and lockout/tagout where hardware work is required.

Causes and Fixes

  1. 1

    Check positioning timeout parameter

    Navigate to HMI > Parameters > Machine Data > Channel > MD35110 SPIND_POSITIONING_TIME and verify current value is adequate for spindle deceleration time.

    Typical values range from 5000-15000ms depending on spindle inertia and drive response

  2. 2

    Monitor actual positioning time

    Use HMI > Diagnostics > Service > Spindle to observe actual time required for M19 completion during manual test.

    Ensure spindle is at safe RPM before testing orientation

  3. 3

    Adjust timeout if necessary

    Increase MD35110 value by 20-30% above observed positioning time and perform power-on reset to activate changes.

DIY Feasiblehigh confidence

Call a technician if:

  • ·Mechanical spindle binding detected
  • ·Drive communication failures persist
  • ·Encoder hardware replacement needed

Prevention

  • Regular spindle brake maintenance
  • Periodic verification of MD35110 timeout values
  • Monitor spindle positioning accuracy trends

Common Mistakes

  • Setting MD35110 timeout too aggressively low
  • Ignoring spindle brake release confirmation
  • Not verifying encoder feedback before parameter changes

Related Alarms

25080250811602121614

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