In this lesson we learn to manage program files on the Mitsubishi M70 control in an orderly and safe way: deleting a single program, preventing the wrong program from being deleted, copying a program under a different number, backing up from NC memory to a CF card/USB, restoring from a backup and problems during file operations. Menu names can vary by builder; here we use the basic logic and general sequence of the operations.
1. What to do before deleting a program
Before deleting a program: determine the correct program number, check that the program is not running actively, make sure it is not called by another main program, take a current backup, check that it is not a builder-special program, and carefully compare similar numbers in the list. For example O1000, O1001, O1010 look very similar so a wrong selection can be made. Program deletion is mostly irreversible; do not delete without a backup.
2. What is the active program?
The active program is the one the control has selected to run or monitor right now. For example if the MONITOR screen shows O1200, O1200 may be active. The control may not allow deleting an active or running program; even if it does, program management can become confused. So before deleting: stop the program, apply RESET if needed, switch to EDIT mode, open a program other than the one to delete, and then return to the program list.
3. Deleting a single program
Let us delete O1200 in NC memory. General sequence: (1) Check the machine is not running. (2) Switch to EDIT mode. (3) Open the PROGRAM/FILE screen. (4) Select MEMORY as the device. (5) Open the program list. (6) Find O1200. (7) Move the cursor onto O1200. (8) Select the DELETE/ERASE command. (9) Re-check the program number on screen. (10) Answer the confirmation with YES/INPUT. (11) Wait for the operation to complete. The delete command may be DELETE, ERASE, FILE DELETE, PROGRAM DELETE or DEL; make sure the cursor is on the correct program before pressing.
4. Deleting by typing the program number
On some M70 applications, deletion can be done by typing the program number without entering the list: O1200 is typed and DELETE is applied. But this method is riskier for beginners: the wrong number can be typed, the letter O can be confused with zero, only a line/word can be deleted while inside the program, and the panel may do an edit-delete instead of a program-delete. So deleting the program by selecting it from the list is safer.
5. Deleting a line and deleting a program are not the same
This distinction is very important. DELETE on the program screen: if the cursor is on a line inside the program (e.g. N40 S1500 M3;), DELETE may only delete that line or the command the cursor is on. DELETE in the program list: if the cursor is on O1200 in the list, the whole program may be deleted. So before pressing DELETE, check which screen you are on.
6. Deleting multiple programs
On some M70 panels multiple programs can be selected for bulk delete (e.g. O1200, O1201, O1202). But bulk delete is not recommended for beginners. The safer method: check each program separately, back it up, delete one by one, and re-check the list after each deletion. Some controls have commands that delete all programs in a certain range or the whole memory; the builder manual must be reviewed before using these.
7. Programs that must not be deleted
Special care must be taken with: the O8000 series, the O9000 series, tool-change programs, measurement macros, probe programs, pallet-change programs, the builder’s service programs, user macros and files used as subprograms. For example if the main program says M98 P9001, O9001 may be a subprogram or machine macro; if deleted, the main program may error or a special machine function may not work.
8. If a program cannot be deleted
If a program cannot be deleted, the reasons: the program may be active (open another program or bring the control to normal with RESET); the program may be running (stop automatic operation); EDIT mode may not be selected (deletion usually needs EDIT); the program may be protected (O8000/O9000 edit-delete protection may be on); the memory protect switch may be on (some machines have a physical MEMORY PROTECT switch; while on, delete/edit cannot be done); the file may be in another operation (if a copy/write/read is in progress, wait). The M700 Handbook states that automatic start is blocked during a file delete/write.
9. Copying a program under a different number
Creating a copy before changing an existing program is a good habit. For example we will change O1200; first we can copy it as O1201. This way O1200 stays original, changes are made on O1201, and if there is an error we can return to the old program.
10. Copying a program within NC memory
If the panel supports this feature: (1) Switch to EDIT mode. (2) Open the PROGRAM/FILE screen. (3) Select the MEMORY device. (4) Find O1200. (5) Select the COPY command. (6) Enter O1201 as the target number. (7) Press INPUT/EXECUTE. (8) Wait for the completed message. (9) Open O1201 and check it. The copy command may be COPY, FILE COPY, PROGRAM COPY or DUPLICATE; not every M70 panel has a direct copy key.
11. Method to use if there is no direct copy
If there is no COPY on the panel: back up O1200 to a CF card/USB → change the program number inside the file to O1201 on the computer → make the file name O1201 too → transfer the program back to NC memory → check the new program. For example if the old program’s first line is O1200, the new file must be O1201. Changing only the file name may not be enough; the O number inside the file must also be checked.
12. Care when changing the program number (subprograms)
When the program number is changed, the subprogram relationships inside it must also be checked. In the example the main program is O1200 but it calls the O1210 subprogram; copying the main program as O1300 does not mean the subprogram will automatically become O1310. Subprogram numbers must be checked separately. The Mitsubishi programming manual uses the O number for program identification and the N number for sequence identification within a program.
O1200
...
M98 P1210
...
M3013. Backing up from NC memory to USB or CF card
Let us back up O1200 in NC memory to an external device: (1) Check the program is not running. (2) Insert the CF card or USB. (3) Switch to EDIT mode. (4) Open the PROGRAM/FILE screen. (5) Select MEMORY as the source device. (6) Find O1200. (7) Select the COPY/OUTPUT/WRITE command. (8) Select CF CARD or USB as the target device. (9) Check the file name. (10) Start the transfer. (11) Wait for the COMPLETED message. Correct direction: MEMORY → USB or MEMORY → CF CARD.
14. Do not confuse source and target device
This is the most important check in backup. Source is where the program is (MEMORY), Target is where the backup will be written (USB). Correct operation: MEMORY → USB. If the wrong selection is made, an old program on the USB can be transferred to NC memory; so before giving EXECUTE/INPUT, check the direction on screen.
15. Naming the backup file
The file name should be plain and clear (e.g. O1200.NC). If a more detailed scheme is wanted, it can be stored on the computer as O1200_2026-07-10.NC, O1200_ORIGINAL.NC, O1200_REV1.NC. But when restoring to the CNC, long file names or special characters can cause problems; the name of the file to be used on the machine should be kept as short as possible.
16. Checking after the backup completes
Do not rely only on the “Completed” message. Do these checks: open the external device in the file list, find the O1200 file, check the file size is not zero, view it if possible, check the program’s first and last line, and if there are subprograms back them up separately too. The main program alone may not be enough.
17. Backing up together with subprograms
The main program below calls the O1210 and O1220 subprograms; so backing up only O1200 is not enough. What to back up: O1200, O1210, O1220. Otherwise, when the program is transferred to another machine, a “subprogram not found” error can occur.
O1200
N10 G21 G17 G90;
N20 M98 P1210;
N30 M98 P1220;
N40 M30;18. Restoring from a backup
To bring a program on the USB/CF card back into NC memory: (1) Switch to EDIT mode. (2) Open the PROGRAM/FILE screen. (3) Select USB/CF CARD as the source device. (4) Find the backup program. (5) Select the COPY/INPUT/READ command. (6) Select MEMORY as the target device. (7) If the same O number exists, read the warning carefully. (8) Start the operation. (9) Wait for the completed message. (10) Open the program in NC memory and check it. Correct direction: USB → MEMORY or CF CARD → MEMORY.
19. If a program with the same number exists
If O1200 exists on both the USB and in NC memory at the same time, the control may ask for overwrite confirmation, warn “program exists” or stop the transfer. Before overwriting: back up the program in memory, check the dates of the two programs, compare the file sizes, compare the contents if possible, and be sure which is current. If it is not clear which is current, do not delete the old file.
20. Creating a backup scheme
To keep programs from getting mixed up, a simple folder scheme can be used: under M70_BACKUP, ACTIVE_PROGRAMS, OLD_VERSIONS, SUBPROGRAMS and MACHINE_MACROS. Program versions can be stored on the computer as O1200_ORIGINAL.NC, O1200_REV1.NC, O1200_REV2.NC. But the O number inside the final file to be transferred to the machine must be correct.
21. Recommended method before editing a program
If a program will be changed: (1) Back up the original to a USB/CF card. (2) Copy the program under a different O number. (3) Make the changes on the copy. (4) Test the program with simulation or dry run. (5) If the result is correct, make the new program the production program. (6) Do not delete the old program immediately. This method makes it easy to revert on wrong changes.
22. What not to do during file operations
While a program is being deleted or copied: do not give CYCLE START, do not remove the USB/card, do not turn off the machine, do not press RESET unnecessarily, do not change the mode, do not start another file operation, do not edit the same program. The M700 Handbook states that automatic start is not possible during a file delete/write and that you must wait until the operation completes.
23. Common problems
- Program will not delete: is EDIT mode selected, is MEMORY PROTECT on, is the program active, is it protected, is a file operation in progress?
- Program will not copy: is the same number in the target, is NC memory full, is the target device inserted, is the file name suitable, are source and target correct?
- Backup to USB fails: is the USB detected, is it write-protected, is there enough free space, is the file system supported, is another operation in progress?
- Backup program will not open: is the file empty, is there an O number inside, are the line ends suitable, was the transfer interrupted, is the extension recognized?
24. Application example and lesson summary
Safe sequence to back up and delete O1200: check O1200 is not running → insert USB/CF card → switch to EDIT mode → open the PROGRAM/FILE screen → select MEMORY as source → find O1200 → select USB/CF CARD as target → start COPY/OUTPUT → wait for COMPLETED → check the file on the external device → select MEMORY again as the device → find O1200 in the list → re-check the number → select DELETE → confirm → verify it is removed from the list. In this lesson we learned deleting a single program, the line-vs-program delete difference, care with active/protected programs, copying under a different O number, backing up to USB/CF card, backing up subprograms together, restoring, and what not to do during file operations.
Next lesson — Lesson 8: Stopping, canceling and restarting a program normally (temporary stop with Feed Hold, Single Block stop, M00/M01 program stops, cancel with Reset, resetting the program to the start, and when to resume from where it stopped vs start from the beginning).