057

Identify the exact block number from the alarm screen (ALARM > displayed block number). Review the G02 or G03 arc command for radius R value and endpoint coordinates X, Y, Z.

Verify the arc geometry: Calculate the distance from start point to endpoint and compare to 2×R. For valid arcs, the straight-line distance between start and end points must be less than or equal to 2×R (diameter). If greater, the arc is geometrically impossible.

If using I, J, K format instead of R, verify the arc center offsets. Check that both the start point and endpoint are equidistant from the calculated center point (start + I,J,K offset). Use PROGRAM > check mode or graphical verification if available.

Correct the program by adjusting either the R value to accommodate the endpoint distance, or modify the endpoint coordinates, or switch from R format to I, J, K format with verified center calculations. Parameter 3450 (arc radius tolerance) can be checked but should not be modified without understanding implications.

Do not arbitrarily increase parameter 3450 tolerance values as this masks programming errors and may cause dimensional inaccuracies

Review the alarm block and the previous block for chamfer ,C or corner radius ,R commands. Check if the chamfer or radius value exceeds the available distance on either the preceding or current move.

Calculate the maximum allowable chamfer/radius: For 90-degree corners, maximum ,C = shorter leg length, maximum ,R must allow both approach and departure tangent lengths. Verify parameter 5004 bit 0 (CHF/CRN) is set to 1 if using these functions.

Reduce the ,C or ,R value to within geometric limits, or modify the programmed move lengths to accommodate the specified chamfer/radius dimensions. Test in PROGRAM > check graphics mode before running.

Verify the current modal state before the alarm block: Check if G90 or G91 is active. Review SYSTEM > PARAM > parameter 1012 bit 0: when set to 0, I/J/K are incremental (Fanuc standard); when set to 1, I/J/K are absolute from program zero.

Check parameter 1013 (absolute/incremental input for each axis independently). Ensure consistent programming method throughout the block. Trace back through program to verify no unintended mode changes occurred.

Correct the program by explicitly stating G90 or G91 in the alarm block, ensuring I, J, K arc parameters match the expected mode per parameter 1012. Standardize on one method (preferably I, J, K incremental with parameter 1012 bit 0 = 0) to avoid confusion.

Changing parameter 1012 affects all programs using arc commands - verify all existing programs before modification

Perform a dry run with SYSTEM > DIAGNOSIS > D2030-D2035 (current absolute position monitor) and D2040-D2045 (relative position) to verify endpoint calculations are resolving correctly through the program sequence.