📷 IMAGE AREA — Mitsubishi M70 MONITOR → RESEARCH → TYPE 1 restart menu and the MSTB History screen
Suggested alt text: Mitsubishi M70 program restart type 1 research menu and MSTB history screen
In this lesson we learn to restart a program interrupted by a power failure, RESET, Emergency Stop, tool breakage or operator intervention using the Program Restart Type 1 method. Type 1 is the easiest restart method on the M70/M700; the operator does not need to enter a program number, line number or block number — the control finds where the program stopped by itself.
1. When is Type 1 used?
Type 1 can be used if the program was interrupted for: a power failure, using Emergency Stop, an accidental RESET, tool breakage, tool wear, the operator stopping the program, or the program being interrupted for another reason. The source document states that Type 1 is used especially for operations that were interrupted while running and are to be resumed from where they stopped.
2. Why is Type 1 easier?
In Type 1 the operator does not need to know the program number, line number, N number or block number; the control finds the previously running program and the point where it stopped by itself. So Type 1 is easier, asks for less data entry, reduces the risk of selecting the wrong line, and is safer than Type 2. But no restart method is automatically completely safe; the tool, axis, spindle and coolant state must also be checked.
3. Check the machine before the restart
Before entering the menus: the machine must be fully stopped; if Emergency Stop is pressed, why it was pressed must be determined; a broken tool must be replaced; the new tool’s length and radius offsets must be checked; the workpiece must not have moved; the vise and clamping elements must be sound; the alarm cause on screen must be cleared; the Z axis must be in a safe position; the other axes must be near the region where the program stopped; Feed and Rapid Override must be lowered. The source document specifically requires that before using Program Restart, the Z axis is in a safe place and the other axes are near the position where the program stopped; when START is given, the machine may move automatically to the restart position.
4. Entering the Type 1 screen (MONITOR → RESEARCH → TYPE 1)
Assume the program was interrupted. General sequence: Step 1 – MONITOR press the MONITOR key (the area where the running program and axis states are monitored). Step 2 – RESEARCH press the RESEARCH soft key (it may be translated differently on some screens; in the source the menu name is RESEARCH). Step 3 – TYPE 1 select TYPE 1. The basic sequence in the source is exactly MONITOR → RESEARCH → TYPE 1.
5. Starting the restart search
After the TYPE 1 screen opens, press INPUT; the control starts searching for where the program stopped. The search time can vary by the program size, how much of it ran, and whether the program is in memory or on an external device. During this, do not press RESET, do not change the mode, do not give CYCLE START, and do not change the program selection.
6. Wait for the search to complete
Wait until the “Restart search is completed” message appears on screen; this message shows the control has found the point where the program stopped. Do not proceed to the next stage before the message appears. The M700 alarm handbook states that if you switch to manual mode before the restart search is complete, or do a wrong operation while the restart is in progress, a restart-related warning can occur.
7. What is the MSTB History screen?
After the restart point is found, you need to check which auxiliary commands the machine was running with at the moment it stopped; for this the MSTB HISTORY key is pressed. The MSTB letters generally mean: M auxiliary functions, S spindle speed, T tool number, B second auxiliary function or machine-specific commands. This screen lists the commands the program used up to the restart point.
8. What appears on the MSTB History screen?
As an example, values like S1000, S1500, S2500, T1, T3, T6, M3, M5, M8, M9 may appear. This list may show not just the last command but several commands the program used up to that moment. For example if the program used two different tools before stopping, both T1 and T6 may be in the list. So INPUT is not given to all commands on screen; only the command needed at the restart point is selected.
9. Checking the correct tool
First determine which tool was in use where the program stopped. For example if the active tool is T6: check that T6 is the correct tool in the magazine, make sure the tool in the spindle is T6, if the tool was changed check the length offset, and if a new tool was fitted in place of a broken one re-enter the measurement value. If the wrong tool is selected, there is a serious collision risk during restart.
10. Selecting the spindle speed
The MSTB History screen may have several S values the program used (e.g. S1000, S1800, S2500). If the speed needed where the program stopped is S1800: move onto S1800 with the arrow keys, make sure the value is correct, and press INPUT. This prepares the spindle speed command, or depending on the machine structure it may be applied immediately. Only the correct speed must be selected.
11. Selecting the spindle direction (caution: may run instantly)
If the spindle must turn clockwise, M3 is usually selected: move onto M3 with the arrow keys, check the tool is in a safe position, make sure the door is closed, and press INPUT. Very important: the moment you move onto M3 and give INPUT on the MSTB History screen, the spindle may start turning. This is not just a selection operation; the command can run instantly. If the machine is a vertical machining center, M3 is mostly used; but if the program uses M4, the wrong direction must not be selected.
12. Turning on the coolant
If the coolant must be on where the program stopped, find M8 in the list: move onto M8 with the arrow keys, check the coolant system is safe, and press INPUT. The moment INPUT is given, the coolant may turn on. If coolant is not needed, M8 is not selected.
13. INPUT is not given to every command
The most common mistake in this part is giving INPUT to all values seen in the list. For example if the screen shows S1000, S1500, S2000, T1, T4, T6, M3, M8, only the needed ones are selected. If the restart point needs T6, S2000, M3, M8, only these are confirmed. The source document specifically states that seeing several tools or speeds is normal and that only the wanted value from each group should be selected.
14. Final safety check before START
After the MSTB commands are prepared, START is not given immediately. Check: is the correct tool in the spindle, is the tool offset correct, is the spindle turning in the correct direction, is the speed suitable, is the coolant state correct, is the Z axis safe, are the X and Y axes in a safe position, is the part clamping sound, is the door closed, is Feed Override low, is Rapid Override low, is Machine Lock off? The M700 handbook states that if Machine Lock is active on an axis returning to the restart position, a “Program restart machine lock” alarm can occur.
15. Lower the Feed and Rapid Override values
During restart the machine may first return to the position where it stopped; because this move can be fast, Feed Override low and Rapid Override low should be selected (e.g. Feed Override 10–25%, Rapid Override 5–10%; lower values can be used depending on the job). If the override is at zero the machine may not move; in that case a feed or rapid-motion zero warning may appear on screen.
16. Starting the restart with CYCLE START
After all checks are complete, the CYCLE START key is pressed. The machine may move to the position needed for restart, approach the point where the program stopped, and continue program execution from where it stopped. During this, the operator must watch the tool path, check the axis movements, keep a hand near FEED HOLD, and lower Rapid Override further if needed.
17. If the return to the restart position is not complete
A warning may appear that the return to the restart position is not complete. The M700 handbook states that the “Restart pos return incomplete” warning can occur if automatic start is given before the axis returns to the restart position. As a solution, returning the axes to the restart position manually or (if the machine supports it) using the automatic restart-return function is recommended. In that case, instead of giving START repeatedly, check the state of the axes.
18. If the machine does not move during Type 1
- Feed Override may be zero: raise the Feed value above zero.
- Rapid Override may be zero: raise the rapid rate above zero.
- Machine Lock may be on: Machine Lock must be turned off.
- The restart search may not be complete: wait for the “Restart search is completed” message.
- The axis may not have returned to the restart position: check the warning on screen.
- There may be an alarm: restart will not run until the alarm is cleared.
19. When must Type 1 not be used?
Type 1 must not be relied on directly in these cases: the program was changed afterward, a different program was selected, the program file was deleted and reloaded, the workpiece moved, the workpiece zero was changed, the tool offsets changed but were not verified, it is not clear where the axes are, the point where the program stopped is not safe, or the connection structure changed while the program runs from an external device. In these cases, running the program from the beginning or using Type 2 with an authorized expert may be safer.
20. Short application sequence and lesson summary
General sequence: (1) Check the machine and the stop reason. (2) If there is a broken tool, replace it and verify its offset. (3) Move the Z axis to a safe position. (4) Press MONITOR. (5) Select RESEARCH. (6) Select TYPE 1. (7) Press INPUT. (8) Wait for the “Restart search is completed” message. (9) Open the MSTB HISTORY screen. (10) Check the correct tool. (11) Select the needed S speed and give INPUT. (12) If needed, select M3 and give INPUT. (13) If needed, select M8 and give INPUT. (14) Lower Feed and Rapid Override. (15) Check the axis and tool positions one last time. (16) Give CYCLE START. (17) Watch the restart moves carefully. In this lesson we learned when Type 1 is used, that it finds the program position itself, the MONITOR → RESEARCH → TYPE 1 sequence, the restart search with INPUT, the “Restart search is completed” message, the M/S/T/B commands on the MSTB History screen, that commands can run immediately when INPUT is given, and doing a safe restart with low override.
Next lesson — Lesson 10: Program Restart Type 2 and starting from a specific line (when Type 2 is used, selecting the program manually, Top Search and File Set, entering a line/block number, the risks of starting from a specific point and the differences between Type 1 and Type 2).
📷 IMAGE AREA — Selecting T/S/M commands on the MSTB History screen and confirming with INPUT (spindle/coolant may run instantly)
Suggested alt text: Mitsubishi M70 MSTB history screen selecting tool speed and M command