101140

Access the drive machine data via HMI: Settings > Commissioning > Drive Data > Select affected axis/spindle.

Locate MD138 ROTOR_COLD_RESISTANCE and verify the current value is 0 or blank.

Enter the correct rotor cold resistance value in Ohms from motor nameplate data or manufacturer documentation. Typical values range from 0.5 to 50 Ohms depending on motor size.

Ensure you have the correct motor documentation. Incorrect values will cause improper motor protection and potential thermal damage.

Save the machine data, perform a drive reset (power cycle the drive module or NCK reset), and clear the alarm. Verify motor operates correctly.

Check for additional alarms indicating battery low (1100, 1101) or memory errors. Inspect battery voltage at NCU (should be >3.0V for lithium batteries).

If battery is depleted, replace it immediately. Use Siemens recommended battery type (typically 3V lithium A5E00331143).

Machine data may continue to be lost until battery is replaced. Do not power off the control without saving data to external storage.

Restore machine data from a known good backup (*.ARC or *.INI file) via Archive or Commissioning functions. Verify MD138 contains proper rotor resistance value.

If no backup exists, manually re-enter all motor commissioning data including MD138 from commissioning sheets or motor documentation. Perform complete drive optimization if necessary.

Verify motor type setting in drive MD: Check MD300 (MOTOR_TYPE) or equivalent parameter. Value should match actual motor (1=asynchronous, 2=synchronous, etc.).

Compare configured motor type with actual installed motor nameplate. Verify this is an asynchronous/induction motor that requires rotor resistance parameters.

If motor type is incorrect, reconfigure to match installed motor. If motor is synchronous, MD138 may not be applicable - consult Siemens documentation for your specific 840D version and drive firmware.

Changing motor type requires complete re-commissioning of the drive including speed controller optimization.

For asynchronous motors, ensure MD138 is populated with correct value. For synchronous motors where this parameter is not needed, contact Siemens support to understand why this alarm is triggering.