Fanuc Parameter 1829
A mismatch between the reference loop gain and physical deceleration can cause the axis to miss its target grid point by exactly one pitch of the encoder scale or ballscrew, shifting your machine home position. How to View and Modify Parameter 1829
FANUC 16i, 18i, 21i, 0i-C, 0i-D, 0i-F, and newer 30i/31i series 2-word (Binary / Integer) Data Range Generally 1 to 9999 (represented in units of 0.01s-10.01 s to the negative 1 power Standard Default Typically set to 3000 (which equates to a gain of 30)
Sets the limit for this error while the axis is moving (linked to Alarm 411).
When Parameter 1829 is misconfigured, mismatched across axes, or rendered unstable by mechanical wear, the FANUC system will trigger specific servo alarms ( SV Alarms ): 1. SV 0411 - Excess Error (Moving) fanuc parameter 1829
Understanding FANUC Parameter 1829: Diagnosis and Fixes for Position Loop Gain Matrix Errors
Ensure the automatic lubrication system is functioning and that the ways aren't dry Monitor Position Deviation: Use the CNC's Diagnosis Screen
The primary role of Parameter 1829 is to trigger an emergency stop if an axis moves or drifts while it is supposed to be stationary. A mismatch between the reference loop gain and
Parameter 1829 Value=Rapid Traverse Rate (mm/min or inch/min)60×Servo Feed Forward/Gain×Safety FactorParameter 1829 Value equals the fraction with numerator Rapid Traverse Rate (mm/min or inch/min) and denominator 60 cross Servo Feed Forward/Gain end-fraction cross Safety Factor
Understanding how Parameter 1829 fits into the broader servo parameter ecosystem is crucial for effective system tuning.
If the problem continues despite these steps, contact your machine tool builder or a qualified FANUC service representative. Persistent excess error alarms often indicate underlying issues requiring professional diagnosis. SV 0411 - Excess Error (Moving) Understanding FANUC
The you are seeing (e.g., quadrant marks, servo hum) The current values inside parameters 1825 and 1829
| Alarm Code | Message | Likely Cause Relative to 1829 | | :--- | :--- | :--- | | | Excessive Mismatch | Deviation > 1829 threshold. Check 1829 value vs. rapid rate. | | SV0401 | Servo Mismatch | Similar to 410, often during acceleration. Increase 1829 or reduce acceleration (parameter 1620). | | SV0436 | Soft Thermal (OVC) | Not directly 1829, but repeated mismatch alarms can trigger this if the motor overheats fighting a stall. | | PS0300 | CNC Mismatch | Rare; usually means 1829 is smaller than the in-position width (parameter 1826). |