4100

Check Program Block Sequence

Navigate to Program Manager and examine the NC program around the alarm block. Verify that a valid S-word (S>0) precedes the M03/M04 command.

Use the program editor's search function (Ctrl+F) to quickly locate all S-words and M03/M04 commands in sequence.

Verify Modal S Register

In Machine > Diagnosis > Service > Variables, check the current value of $AA_S[spindle_number] to confirm if a valid speed is stored in the modal register.

The modal S register retains its value across blocks until explicitly changed or reset.

Correct Programming

Add appropriate S-word before M03/M04 or ensure S-word is programmed in the same block (e.g., 'M03 S1000' instead of just 'M03').

Always verify spindle speed limits in machine data MD35000-MD35020 before programming S-values.

Check Spindle Speed Limits

Navigate to Commissioning > Machine Data and examine MD35000 (minimum spindle speed) and MD35010 (maximum spindle speed) for the affected spindle.

Use the machine data search function and filter by 'spindle' to quickly locate all spindle-related parameters.

Verify Gear Stage Configuration

Check MD35100-MD35130 for gear stage definitions and ensure the programmed speed is valid for the current gear range if multiple spindle gears are configured.

Incorrect gear stage machine data can cause valid speeds to be rejected by the NC kernel.

Adjust Programming or Machine Data

Either modify the S-word in the NC program to fall within valid limits or adjust machine data limits if the mechanical spindle capabilities support the desired speed.

Always perform a spindle test run at low speed after modifying machine data to verify proper operation.

Check PLC Spindle Interface

In Diagnosis > PLC > Variable Status, monitor DB21.DBD0 (spindle speed setpoint) and DB21.DBX4.0-4.2 (spindle enable signals) during program execution.

Use the PLC variable monitor table to track real-time changes in spindle interface variables.

Examine Safety Logic

Review PLC program blocks FB1-FB3 for custom spindle interlocks that might be resetting speed values or preventing spindle start conditions.

Never bypass safety interlocks without understanding their purpose and ensuring operator safety.

Verify Spindle Enable Conditions

Check that all prerequisite conditions (chuck closed, tool clamped, doors closed) are satisfied in the PLC logic before the spindle start command is issued.

Use the integrated PLC debugger to step through spindle-related logic and identify where the speed value is being cleared.

Check Reset Behavior Settings

In Machine Data, verify MD20734 (reset behavior for modal values) to understand which modal registers are cleared during reset operations.

MD20734 bit settings determine whether S, F, T, and other modal values are retained or cleared after reset.

Implement Restart Strategy

Use program restart from beginning or add initialization blocks with required S-word before the restart point to re-establish modal conditions.

Always verify tool position and workpiece setup when restarting programs after a reset.

Configure Modal Retention

If operationally acceptable, modify MD20734 to retain spindle speed through reset cycles, or implement PLC logic to restore previous modal values.

Consider using INITIAL_INI.SPF or similar initialization programs to automatically set common modal values after reset.