Siemens SINUMERIK codes
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Siemens SINUMERIK Controller

Servo/Axis · Intermediate · 30-120 minutes

Alarm 300774

Siemens 300774 - Axis drive asynchronous mode: changeover speed invalid

This alarm occurs due to an invalid changeover speed setting in mixed MSD/AM operation, requiring modification of machine data (MD 1465 or MD 1466) to ensure closed-loop control in AM mode.

Siemens SINUMERIKServo/AxisIntermediate30-120 minutes

300774

Siemens 300774 - Axis drive asynchronous mode: changeover speed invalid

Axis drive asynchronous mode: changeover speed invalid

In mixed operation MSD/AM (MD 1465 > 0) only closed-loop controlled AM mode is allowed (MD1466 <= MD1465). - Modify MD 1465: $MD_SWITCH_SPEED_MSD_AM (switchover speed MSD/AM) - Modify MD 1466: $MD_SWITCH_SPD_OPEN_LOOP_AM (switchover speed closed-loop/openloop control AM) The alarm can be reprogrammed in the MD ALARM_REACTION_CHAN_NOREADY (channel not ready) Control reaction: NC not ready. The NC switches to follow-up mode. Channel not ready. NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm. Channel not ready.

Root Cause Summary

This alarm occurs due to an invalid changeover speed setting in mixed MSD/AM operation, requiring modification of machine data (MD 1465 or MD 1466) to ensure closed-loop control in AM mode.

Safety

  • Drive/power/encoder circuit: hazardous voltages may remain in the DC link after power-off. Lock out / tag out, wait for discharge per the drive documentation, and use qualified personnel only.

Causes and Fixes

  1. 1

    Check Machine Data

    Access MD 1465 ($MD_SWITCH_SPEED_MSD_AM) and MD 1466 ($MD_SWITCH_SPD_OPEN_LOOP_AM) via the control panel.

  2. 2

    Adjust Values

    Ensure MD 1466 <= MD 1465 to enforce closed-loop control in AM mode as per alarm description.

  3. 3

    Reset and Test

    Save changes, reset the control, and test the program to confirm the alarm is cleared.

DIY Feasiblehigh confidence

Call a technician if:

  • ·If adjusting MD values does not resolve the issue
  • ·If unsure about correct MD settings for the machine

Prevention

  • Verify machine data settings before running mixed MSD/AM operations
  • Simulate programs to catch configuration issues early
  • Always backup machine data before making modifications
  • Document any MD changes for future reference

Common Mistakes

  • Overlooking MD value relationships (MD1466 <= MD1465)
  • Failing to save changes after adjusting machine data

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