20097

Access Diagnostics > Axis Functions > Brake Test menu in HMI. Verify the AXIS DIRECTION shown in the test dialog matches the physical axis orientation (identify if axis is vertical Z, B-axis tilting head, etc.).

Do not proceed with brake test until direction is confirmed correct for the mechanical load case

Check parameter MD20050 (Axis type) and MD20051 (Axis kind) to confirm axis classification. For vertical axes, verify MD20100 contains the correct load torque value accounting for full load mass.

Manually select the opposite travel direction in the brake test menu and re-run the diagnostic test. Document which direction passes/fails. Contact Siemens support with results if both directions fail.

Running brake test in wrong direction multiple times may cause brake wear; limit attempts to 2 per direction

If test passes in reversed direction, recalibrate workpiece offset or machine geometry setup. Verify G-code contains correct directional logic for this axis in your application programs.

Navigate to Parameterization > Axis > Load Data menu. Cross-reference MD20100 against the actual maximum load mass mounted on the axis. Calculate expected torque: Load (kg) × 9.81 m/s² × lever arm (m) = Load Torque (Nm).

Incorrect load torque values are the most common cause of 20097; verify with mechanical engineering or CAM setup documentation

Check if workpiece or clamping fixture was recently added/removed that changes the axis inertia or load distribution. Use machine diagnostics to measure actual load torque via the drive encoder feedback during a controlled jog movement.

Update MD20100 with measured or calculated load torque. Set MD20101 (brake test torque) to approximately 110-120% of the actual load to provide margin. Perform a dry-run brake test in both directions to confirm.

Over-tuning MD20101 may mask actual brake degradation; set conservatively

If load is variable or multi-configuration, create separate parameter sets using SINUMERIK 840D recipe/variant functionality, or implement auto-load compensation via PLC logic in OB251 (load-dependent parameter adjustment).

Review parameter MD20003 (Axis direction) setting: 0 = positive direction matches motor shaft rotation, 1 = inverted. Cross-reference against machine documentation for actual motor-to-load mechanical arrangement (gearbox ratio, screw pitch, pulley direction).

Changing MD20003 affects all motion logic for the axis; coordinate with programming department before modification

Verify parameter MD20006 (Feedback direction) matches MD20003 if an external encoder is used. Misalignment between command direction and feedback direction causes the NCK to miscalculate load torque direction.