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Review the NC program block at the reported position (Channel %1, Block %2). Check the G96 statement for LIMS parameter syntax: G96 S<cutting_speed> LIMS=<value>.

Use the DCC (Detailed Cycle Check) or program analysis in NCK to isolate the exact block.

Verify the LIMS value is positive and within valid range (0.1–999,999.9 rev/min). Correct any negative sign or arithmetic error in the NC code.

Do not simply remove LIMS; if constant cutting speed is required, provide a valid positive value.

If LIMS is set via variable ($AC_LIMS or custom variable), trace the variable assignment and ensure the source data is correct.

Reload the corrected NC program and execute a dry-run cycle to confirm the alarm clears.

In the NC Editor or Siemens HMI, navigate to the problematic block and identify any variables or expressions in the LIMS statement (e.g., LIMS=R1, LIMS=R1+R2).

Use the Variable Monitor (in Operate menu or via Diagnostics > Variables) to check the runtime values of all variables referenced in the LIMS expression. Confirm they result in a positive value.

Watch variables during single-block execution to trace when the value becomes negative.

Add initialization logic before the G96 block to ensure variables are set to valid positive values. For example, add R1=500 before LIMS=R1.

Re-run the program and confirm the LIMS variable now evaluates to a positive number within range.

Access the Machine Data menu (Diagnostics > Machine Data) and verify spindle-related parameters: MD 30320 (max spindle speed), MD 30321 (min spindle speed), and MD 31000 (spindle type). Ensure values are positive and reasonable.

Check any custom macro or M-function that runs before the G96 block. Search the macro for commands that set spindle limits or speed; ensure they do not produce negative results.

Use the Macro List (Program > Macros) to identify active M-functions and review their code.

If machine data was recently edited or the system was updated, reload the machine data from backup or verified configuration and restart the NCK.

Retry the G96 block with a hardcoded positive LIMS value (e.g., LIMS=1000) to isolate whether the issue is in the NC program or machine configuration.