016

Review the line triggering the alarm and verify M98 includes a P address with valid program number (e.g., M98 P1000).

Confirm the called subprogram (O number) actually exists in memory or on the control's program list.

Check that the P address format matches your control's requirements - some systems use P followed by 4-8 digits, others may require specific formatting.

If using L address for repeat count, verify it's formatted correctly (L1-L9999) and positioned after the P address.

Verify M99 is only used at the end of subprograms (O1000-O9999 range), not in the main program unless intentionally creating an endless loop.

Using M99 in a main program creates an infinite loop - ensure this is intentional and controlled.

If M99 includes a P address for jumping to a sequence number, confirm the N number exists in the calling program and is formatted correctly.

Check for multiple M99 commands in a single subprogram or conditional statements that may cause improper execution flow.

Replace M99 with M30 or M02 if the intent is to end the main program rather than return from a subroutine.

Count the subprogram nesting depth - ensure you haven't exceeded 4 levels (subprogram calling subprogram calling subprogram, etc.).

Nesting depth limits vary by control model - 0i models typically allow 4 levels, older controls may allow only 3.

Verify the control is in AUTO or MEM mode, not MDI or EDIT mode when attempting to run programs with M98/M99.

Check parameters 3107 and 3108 (subprogram call settings) to ensure M98/M99 functionality is enabled and configured correctly.

Changing parameters requires proper authorization and may affect other machine operations - document original values before modification.

Review available program memory - if memory is full or fragmented, the control may not be able to execute subprogram calls properly.