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Siemens SINUMERIK Controller
Servo/Axis · Intermediate · 30-120 minutes
Siemens 300749 - Axis drive conversion factor between motor and load too large
This alarm occurs when the conversion factor between motor and load systems exceeds allowed limits (µm_to_incr > 65535 or motor-to-load factor > 1). Fix by adjusting the relevant machine data or parameters.
300749
Siemens 300749 - Axis drive conversion factor between motor and load too large
Axis drive conversion factor between motor and load too large
The conversion factor from the motor system [increments] to the load system [µm/mdeg] is larger than 1 or the factor which converts the load system to the motor system is larger than 65535. Conditions: The condition for the factor load system to motor system is: µm_to_incr <= 65535 The condition for the factor motor system to load system is: incr_to_µm <= 1 with µm_to_incr = 1 / incr_to_µm Formula for rotary axis: The following applies for rotary motor encoder and rotary axis: incr_to_µm(n) = (MD1321 SAFE_ENC_GEAR_DENOM(n) / (MD1322 SAFE_ENC_NUMERA(n)) * incr_to_µm_rot_rotax with n = 0. 7 (gear stage) and incr_to_µm_rot_rotax = (360000 / 8192) * (1 / MD1318 SAFE_ENC_RESOL) - MD 1318 SAFE_ENC_RESOL (number of encoder lines per revolution) - MD 1321 SAFE_ENC_GEAR_DENOM[n] (encoder/load gear denominator) - MD 1322 SAFE_ENC_GEAR_NUMERA[n] (encoder/load gear numerator) Formula for linear axis: The following applies for rotary motor encoder and linear axis: incr_to_µm(n) = (MD1321 SAFE_ ENC_ GEAR_ DENOM(n) / (MD1322 SAFE_ ENC_ NUMERA(n)) * incr_to_µm_rot_lin incr_to_µm_rot_lin = (1000 / 8192) * (1 / MD1318 SAFE_ENC_RESOL) * MD1320 SAFE_ENC_GEAR_PITCH Explanations: - MD 1318 SAFE_ENC_RESOL (number of encoder lines per revolution) - MD 1320 SAFE_ENC_GEAR_PITCH (spindle pitch) - MD 1321 SAFE_ENC_GEAR_DENOM[n] (encoder/load gear denominator) - MD 1322 SAFE_ENC_GEAR_NUMERA[n] (encoder/load gear numerator) - n = 0. 7 (gear stage) Request: During boot-up of the control Control reaction: Mode group not ready. Channel not ready. NC Start disable in this channel. Interface signals are set. Alarm display. NC Stop on alarm.
Root Cause Summary
This alarm occurs when the conversion factor between motor and load systems exceeds allowed limits (µm_to_incr > 65535 or motor-to-load factor > 1). Fix by adjusting the relevant machine data or parameters.
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
Check machine data
Access the machine data parameters related to axis conversion factors (e.g., MD10200, MD10210).
- 2
Adjust values
Modify the conversion factor to ensure µm_to_incr <= 65535 and motor-to-load factor <= 1.
- 3
Reset and test
Save changes, reset the control, and test the axis movement.
Call a technician if:
- ·If machine data adjustments do not resolve the issue
- ·If unsure about correct parameter values
Prevention
- Validate machine data during commissioning with qualified personnel
- Document parameter changes with approval and verification procedures
- Maintain backup copies of working machine data configurations
- Implement change control procedures for machine data modifications
Common Mistakes
- Entering incorrect conversion values
- Overlooking axis-specific settings
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