20124

Navigate to Siemens HMI > Diagnosis > Alarms and note the axis number in alarm 20124. Cross-reference with NC program active G-code compensation calls (e.g., G331, G332, G335 for geometry; G337 for wear).

Do not clear the alarm until root cause is identified; clearing masks the contour error that has already occurred.

In NCK > Parameters > Machine Data, locate $MA_CEC_MAX_SUM for the affected axis. Default is typically 99999. Check $MA_GEOM_COMP_MODE (MD10700), $MA_THERMAL_COMP_MODE (MD10720), and $MA_WEAR_COMP_MODE (MD10730) to confirm which compensation channels are active (value 1 or 2 = enabled).

Review the compensation table values in NCK > Tables > Geometry/Thermal/Wear Compensation. Sum the largest positive and negative offset values from all active tables for the affected axis. If sum exceeds $MA_CEC_MAX_SUM, either disable non-critical compensation channels or increase $MA_CEC_MAX_SUM in MD10710 (if machine design allows).

Increasing $MA_CEC_MAX_SUM beyond machine mechanical limits can cause axis overtravel or collision.

Measure the actual part produced during the alarm condition using coordinate measuring machine (CMM). Compare against print tolerance to quantify contour error. Document findings and adjust compensation strategy (e.g., disable thermal comp if ambient stable, consolidate wear offsets into single table).

In NCK > Parameters > Machine Data, examine MD10690 and MD10695 for the alarmed axis. Verify that each compensation table is assigned to exactly one axis channel. Cross-reference table IDs in the Compensation Tables menu (NCK > Tables) to ensure no duplicate assignments.

Check the NC program (source code or DIN-code viewer in HMI) for multiple compensation activate commands on the same axis within a single block or consecutive blocks (e.g., G331 followed immediately by G335 on X-axis). If found, ensure only one compensation is active per axis at runtime.

Review Part Program > Program > List for G-code sequences such as G331 (geom comp on), G337 (wear comp on), G332 (thermal comp on) applied to the same axis without intervening deactivation (G330). If stacking is intentional (e.g., combined thermal + wear), verify that individual table offsets are small enough that their sum remains under $MA_CEC_MAX_SUM.

Reset compensation assignment: In NCK > Machine Data, set $MA_COMP_TAB_ASSIGN to 0 (disable) for redundant tables, save, and perform a warm restart (Ctrl+Shift+F2 in most Siemens HMI versions). Re-enable only required compensation and rerun part program.