What causes Siemens SINUMERIK alarm 61804?

Work offset or tool length compensation value incorrect, placing the programmed position beyond the reference limit. Programming error — wrong coordinate sign or value in the block. G-code coordinate system not set up correctly before programming the move. Machine data for the reference point position incorrect. Program using machine coordinates (G53) with an incorrect value.

How do I fix Siemens SINUMERIK alarm 61804?

1. Check the programmed coordinates in the flagged block against the machine travel limits. 2. Verify the active work offset (G54-G59) and tool length compensation values are correct. 3. Confirm the coordinate system (G54 etc.) is appropriate for the programmed position. 4. If using G53 machine coordinates, verify the values are within machine travel. 5. Check the reference point position machine data if the limit appears incorrect.

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Siemens SINUMERIK Controller

Servo/Axis · Intermediate · 30-120 minutes

Alarm 61804

Siemens 840D 61804 - Channel block: Progr. position exceeds reference point

Alarm 61804 indicates that the programmed intermediate position or current actual position (ISPOS) falls behind the machine's reference point, violating the valid travel range defined by MD32100 (RefPoint) and MD32110 (MaxPos). This occurs when NC program coordinates reference negative machine positions that exist outside the calibrated datum after homing.

Siemens SINUMERIKServo/AxisIntermediate30-120 minutes

61804

Siemens 840D 61804 - Channel block: Progr. position exceeds reference point

Channel block: Progr. position exceeds reference point

Root Cause Summary

Alarm 61804 indicates that the programmed intermediate position or current actual position (ISPOS) falls behind the machine's reference point, violating the valid travel range defined by MD32100 (RefPoint) and MD32110 (MaxPos). This occurs when NC program coordinates reference negative machine positions that exist outside the calibrated datum after homing.

Safety

Refer to Siemens documentation
Ensure qualified technician performs repairs

Causes and Fixes

1
Execute machine homing cycle (G74 or OEM-specific homing routine) on the affected channel. Monitor Diagnostics > NCK > Axis > RefPointActive flag to confirm reference point establishment.
Do not skip homing; manual jog to zero is insufficient for encoder synchronization.
2
Verify MD32100 (RefPoint) and MD32110 (MaxPos) are correctly set in Siemens HMI under Diagnostic > Parameters > Machine Data > Axes > [Channel] > Geometry. RefPoint should match your machine's home position; MaxPos should define maximum positive travel from reference.
3
Check MD32120 (MinPos) to ensure the negative travel boundary is set correctly. Programmed positions must satisfy: MinPos ≤ position ≤ MaxPos relative to RefPoint.
4
Clear alarm, re-execute homing, then test program with G00 X0 to verify reference frame is locked. If alarm persists, check encoder hardware (absolute encoder battery, resolver connection) via Diagnostics > Hardware.

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