been detected in the CNC program
Cycle End indicator lights will turn ON only if M00-M01-M02-M30 is detected in the part program
Note that the above illustration does not contain miscellaneous function M02. This function is still supported for backward compatibility but is not used anymore.
As all four indicator lights are directly related to the contents of a part program, it is very important to understand how they affect CNC machine operation.
M00 - Program Stop
Program Stop M00 is typically included in the program if the CNC operator has to perform some task for each individual part of the batch, without exceptions. For example, applying special lubricant for a tapping tool, flipping or repositioning the part, readjusting a clamp, doing a mandatory dimensional check, etc., are all good reasons to include M00 in the part program. Program processing will always be temporarily stopped with M00, without any interference from the CNC operator. The M00 indicator light will only turn ON when the miscellaneous function M00 is detected during program processing.
Typical program application will be at the end of the tool, for example:
...
N31 G00 Z2.0 M09
N32 G28 Z2.0 M05
N33 M00 (PLACE PART IN FIXTURE 2)
It is a good programming practice to include a descriptive comment (message) with the M00 function.
Optional Program Stop M01 is very similar to M00, but the CNC operator does have a choice to use it or not to use it. By turning the Optional Stop switch ON (located on the operation panel), any encounter of M01 in the part program will force the program processing (execution) to stop until the Cycle Start button is pressed.
Both illustrations below show the indicator light status when program processing encounters the M01 function:
Similar to M00, typical program application of M01 will be at the end of the tool, for example:
...
N31 G00 Z2.0 M09
N32 G28 Z2.0 M05
N33 M01
Usually, there is no comment (message) attached to the M01 function.
In either case, when M00 or M01 program function is detected, many machine activities will be stopped:
| ▪All axis motion will stop | |
| ▪Spindle rotation will stop | ... M05 state |
| ▪Coolant will be turned OFF | ... M09 state |
If the program is written correctly, each toolpath that follows M00 or M01 function will include spindle speed and coolant functions, even if no M05 or M09 had been programmed.
Look for missing spindle speed and coolant in the blocks following M00 or M01
Most Fanuc controls support two Program End functions. One of the functions is the old M02, the other is the much more common M30. In the old days of paper tape, M02 was used for a loop tape (that is tape spliced at its ends), because when the end of program had been reached, the tape was physically at its beginning because of the loop. No tape rewind was necessary to use in the program. To accommodate tapes that were too long to form a loop, M30 function replaced the M02 function in the program, with almost identical results. In case of M02, the tape did not rewind to its beginning, in case of M30, the tape was forced to rewind.
Today, there is no physical tape used as a program source anymore, but both functions are still available in virtually all Fanuc control systems. M30 function is the normal standard, but M02 function is still supported, mainly for compatibility with old programs. The word ‘rewind’ takes on a new meaning, and is now interpreted as ‘return to the top of program’.
Many modern controls treat M02 the same as M30 and will rewind (return) to the program beginning (top)
Errors / Alarms / Faults
When checking the status indicator lights, make sure all light bulbs are functioning properly
This comment applies to all indicator lights but it is even more important for the group that shows red lights. Seeing red - that is, a red status indicator light on the Operation Panel - is generally not a good situation. It indicates that something has gone wrong either in the part program itself or during actual machining.
This is the third common group of lights that indicate a certain condition or situation. Usually, there are at least two indicator lights on every control system:
| ▪Alarm | ... general alarm or error condition |
| ▪Lube | ... machine slides lubrication alarm |
The first light is often called just ‘Alarm’ - this is a non-descriptive name that covers all kind of alarms. Also worth note is that some controls use other words, like ‘Error’ or ‘Fault’ with the same meaning. Fanuc controls generally use the word ‘Alarm’. Regardless of the definition, the results
