How do I fix Siemens SINUMERIK alarm 300785?

1. Please inform the authorized personnel/service department. 2. For standard motors: Reset the drive (delete the bootfile) and repeat the startup. 3. For third-party motors: Check and, if necessary, refer to the motor data sheet to correct MD 1136: $MD_MOTOR_NOLOAD_CURRENT (motor no-load current). 4. Clear alarm with the RESET key in all channels. Restart part program. 2-759

Siemens SINUMERIK codes

axismd.ai

Siemens SINUMERIK Controller

Servo/Axis · Intermediate · 30-120 minutes

Alarm 300785

Siemens 300785 - Axis drive zero load current less than or equal to zero

This alarm occurs when the motor no-load current value in MD 1136 is set to zero or less, often due to incorrect machine data configuration. Fix by updating the parameter with a valid value.

Siemens SINUMERIKServo/AxisIntermediate30-120 minutes

300785

Siemens 300785 - Axis drive zero load current less than or equal to zero

Axis drive zero load current less than or equal to zero

The value in MD 1136: $MD_MOTOR_NOLOAD_CURRENT (motor no-load current) is less than or equal to zero. 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 when the motor no-load current value in MD 1136 is set to zero or less, often due to incorrect machine data configuration. Fix by updating the parameter with a valid value.

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
SAFETY: Power Down and Lock Out
Turn off main power, engage lockout/tagout procedures, and ensure all axes are secured before accessing machine data.
2
Access Machine Data
Navigate to the machine data parameters via the control panel under diagnostics or setup mode. Ensure you have proper authorization level.
3
Update MD 1136
Set a valid positive value for $MD_MOTOR_NOLOAD_CURRENT as per motor nameplate specifications or manufacturer documentation. Typical values range from 0.1-2.0A depending on motor size.
4
Reset and Test
Save changes, perform a controlled restart following proper startup procedures, and test in manual mode before running production programs.

DIY Feasiblemedium confidence

Call a technician if:

·If access to machine data is restricted or unclear
·If the alarm persists after setting a valid value
·If you are not authorized to modify machine data parameters
·If motor specifications are unknown or unclear

Prevention

Regularly back up machine data settings
Verify MD values after control updates or resets

Common Mistakes

Entering a zero or negative value in MD 1136
Overlooking documentation for correct motor parameters

Seeing Multiple Alarms?

Seeing another alarm with this one? Enter the code.

Get machine-aware diagnosis

AxisMD logs alarms against your actual machines, tracks patterns, and gives AI context your manual doesn't have.

Start free

Was this guide helpful?

Always verify with your machine manual or a certified technician before performing service procedures.