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Check Active Program

Press LIST PROG to view the current program. Identify the last executed M98 or G65 call before the alarm occurred.

Use the program pointer position shown in the display to identify exactly where execution stopped.

Verify Subprogram Structure

Navigate to the called subprogram using EDIT mode. Scroll to the end and verify an M99 statement exists as the final line.

Never edit programs while in cycle - always press RESET first.

Add Missing M99

If M99 is missing, position cursor at program end and type 'M99' followed by EOB. Press ALTER to save the change.

For conditional returns, use M99 P[line number] to return to specific program lines.

Test Program Execution

Press RESET, then run the program in single block mode (SINGLE BLOCK button) to verify proper macro completion.

Check Macro Variables

Press SETTING, then navigate to VARIABLES page. Review macro variables #1-#33 and #100-#999 for unexpected values or <EMPTY> status.

Look for variables with extremely large values (>999999) which can cause calculation errors.

Clear Problematic Variables

Select suspicious variables and press DELETE or set to #0. Focus on variables used in spindle speed calculations (#3000 series).

Clearing #100-#199 variables affects all programs - document values before clearing.

Review Macro Logic

In EDIT mode, examine G65 macro calls for proper variable assignments and mathematical operations that could cause overflow.

Use brackets for calculation order: #1=[#2+#3]*#4 instead of #1=#2+#3*#4

Test with Known Values

Manually set macro variables to known good values in MDI mode using #1=100, etc., then re-run the macro.

Identify Loop Structure

In EDIT mode, search for WHILE/END statements or GOTO/N-line combinations in the problematic macro program.

Use SEARCH function (press SEARCH key) to quickly find 'WHILE', 'GOTO', or 'IF' statements.

Check Loop Exit Conditions

Verify that WHILE loops have proper exit conditions and that variables controlling the loop are being modified within the loop.

Ensure loop counter variables are actually incremented - #1=#1+1 must be inside the loop.

Validate GOTO Targets

Confirm GOTO statements reference valid N-line numbers and that the logic allows progression beyond the target line.

Add temporary M00 stops in suspected loop areas to debug execution flow.

Set Loop Limits

Add safety counters to loops: IF[#1 GT 1000]THEN#3000=131(LOOP LIMIT EXCEEDED) to prevent infinite execution.

Trace Call Stack

Review the program structure to identify M98/G65 calls within subprograms. Count the nesting levels from main program to deepest call.

Create a visual map: Main→Sub1→Sub2→Sub3 to track nesting depth.

Restructure Deep Nesting

Reorganize programs to reduce nesting depth. Combine simple subprograms or use sequential calls instead of nested calls.

Always backup original programs before restructuring - use SAVE TO MEMORY function.

Use Local Subprograms

Replace some M98 P#### calls with local subprograms (M98 P#### L# format) to reduce memory stack usage.

Local subprograms (after M30) don't count toward nesting limits the same way.

Test Simplified Structure

Run the restructured program in SINGLE BLOCK mode to verify proper execution without nesting limit issues.

Check Spindle Parameters

Press SETTING, go to PARAMETERS page, and review parameters 10-19 (spindle) and 50-59 (speeds/feeds) for recent changes.

Parameter changes are logged - check the parameter change log if available.

Review System Variables

In VARIABLES page, check #3000-#3999 system variables, particularly #3000 (alarms), #3001 (spindle load), and #3027 (spindle speed).

Never modify #3000 series variables unless specifically required by macro logic.

Isolate Spindle Commands

Temporarily comment out (add semicolon) spindle-related commands in the macro to test if the macro completes without spindle interaction.

Use M05 to stop spindle before macro execution if spindle state is causing conflicts.

Sequence Spindle Operations

Restructure macro to complete all calculations before issuing spindle commands, avoiding parameter changes during active spindle operations.