Mitsubishi M700 Alarms & Parameters

Alarm Classes — Decoding the Prefix

Every Mitsubishi alarm starts with a class code that tells you what kind of problem you have before you read another word. Most classes add a four-digit error number after the message text (e.g., M01 Operation error 0004) — that number is what you look up.

Prefix	Class	What it means
M01	Operation errors	The machine is refusing to move or start — interlocks, overrides at zero, stroke ends, mode switches. Almost never a program bug; usually a switch, a signal, or the PLC sequence.
T01 / T02 / T03	Stop codes	Not faults — explanations. T01 (01xx) = why cycle start won't go, T02 (02xx) = why feed hold happened, T03 (03xx) = why the block stopped.
S01 / S03 / S04	Servo/spindle alarms	Drive-level faults (overcurrent, overheat, encoder trouble). The prefix tells you how to reset it — see the reset table below.
S02 / S51	Initial parameter errors / parameter errors	A servo or spindle parameter is out of range or inconsistent.
S52 / S53	Servo / safety-function warnings	Warnings — the axis keeps running, but something needs attention (e.g., battery, overload trend).
Y	MCP alarms	NC-to-drive communication and amplifier detection problems (e.g., `Y02 System alm: Process time over`).
Z	System alarms	Control-unit level: `Z52` battery fault, `Z53` CNC overheat, `Z55` RIO communication stop, `Z59` accel/decel time constant too large.
Z70 / Z71	Absolute position detection	Lost or corrupted zero-point data, encoder backup voltage drop. Usually means a zero-point re-initialization is in your future.
Z8*	Distance-coded reference scale errors	Scale feedback problems on distance-coded reference systems.
EMG	Emergency stop	E-stop chain is open — the message names the source.
L	Computer link errors	Host communication (drip-feed / computer link B) faults.
U	User PLC alarms	Raised by the machine builder's ladder — check the builder's manual, not Mitsubishi's.
N	Network service errors	Network/Ethernet service problems.
P	Program errors	Your G-code. The fix is almost always "correct the program" — the P-number tells you what to correct.

Servo alarm reset method is encoded in the prefix:

Prefix	Type	How to reset (after fixing the cause)
S01	PR	Turn NC power OFF and back ON
S03	NR	Press the NC RESET key
S04	AR	Turn the drive unit power OFF and back ON

Common Alarms

The alarms below cover most of what actually shows up on the shop floor. Causes and remedies are condensed from the M700BM/M700UM Alarm/Parameter Manual.

Alarm	Name	Cause	Fix
Operation errors (M01) — machine won't move
M01 0004	External interlock axis exists	External interlock input signal is OFF for an axis	Release the interlock; check the sequence and for broken wires in the interlock signal line
M01 0005	Internal interlock axis exists	Servo OFF active, axis removed, or manual/auto simultaneous axis commanded from auto	Release servo OFF; perform the correct operation for the removed axis
M01 0006	H/W stroke end axis exists	An axis is sitting on a hard overtravel limit switch	Jog off the limit manually; check the limit switch and wiring
M01 0007	S/W stroke end axis exists	Stored stroke limit (soft limit I, II, IIB or IB) reached	Move off manually; check soft-limit parameters (`#2013`/`#2014`)
M01 0101	No operation mode	No mode selected — mode-select switch or signal line problem	Check the MODE SELECT switch, wiring, and sequence program
M01 0102	Cutting override zero	Feed override dial on the panel is at 0%	Turn the override up; if it isn't at 0, check the signal line for a short
M01 0105	Spindle stop	Spindle stopped during synchronous feed / thread cutting	Start the spindle; check the spindle encoder cable, connectors and pulse
Stop codes (T) — why it won't start / why it stopped
T01 0101	Axis in motion	Cycle start pressed while an axis is still moving	Wait for all axes to stop, then start again
Program errors (P) — fix the G-code
P33	Format error	Command format in the block is not correct	Correct the program block
P34	Illegal G code	G code not in the specifications, or illegal G during coordinate rotation	Correct the G code address; check the option spec
P62	No F command	No feedrate commanded — power-on default modal is G01, so a bare move alarms	Add an F command (also required with thread lead commands)
P70	Arc end point deviation large	Start/end points and center don't agree on the arc	Correct start/end/center/R values and their signs; check for a scaling-valid axis
P71	Arc center error	Center can't be computed in R-specified circular interpolation	Correct the address values in the block
P132	Spindle rotation speed S=0	No spindle speed command issued	Add the S command
P152	No intersection	Cutter comp (G41/G42) can't find an intersection point after skipping a block	Correct the toolpath around the comp move
P153	Compensation interference	Tool radius / nose R comp would gouge (interference detected)	Correct the program — larger geometry or smaller tool
P181	No spindle command (tap cycle)	No S commanded in synchronous tapping	Command S with the tap; if `#8125`=1 it must be in the same block
P230	Subprogram nesting over	More than 8 nested subprogram calls	Flatten the call structure to 8 levels or fewer
P232	No program No.	Called program not found (or IC-card file name doesn't match O number)	Load the program; check subprogram storage-destination parameters and that the device is mounted
P277	Macro alarm message	A macro executed `#3000` — this is your macro talking	Read the operator message on the diagnosis screen; see the builder's manual for the macro package
P283	Divided by zero	Denominator of a macro division is zero	Guard the divisor in the expression
P430	R-pnt return incomplete	Axis commanded before reference position return was done	Do a manual reference return first
P460	Tape I/O error	Error in the tape reader / I/O device during input	Check device power and cables; correct the I/O device parameters
Servo/spindle alarms (S01/S03/S04) — drive faults, by error number
0025	Absolute position data lost	Absolute position data lost in the detector (battery/encoder)	Restore backup power, then re-initialize the zero point
0032	Power module overcurrent	Drive power module detected overcurrent	Check motor power cables and drive; axis dynamic-stops
0033	Overvoltage	Main-circuit bus voltage exceeded allowable value	Check regen circuit and incoming power
0046	Motor overheat	Motor or motor-side detector overheat (or thermistor circuit open/shorted)	Let it cool; check the duty cycle and thermistor wiring
0050	Overload 1	Overload detection reached 100% — motor or drive overloaded	Reduce the load/duty; check for mechanical binding
0052	Excessive error 1	Position tracking error during servo ON was excessive	Check for a crash or binding; verify servo tuning
0058 / 0059	Collision detection (G0 / G1)	Disturbance torque exceeded the allowable value in rapid / cutting feed	Find what it hit; axis executes a maximum-capacity deceleration stop
System alarms (Z)
Z52 000x	Battery fault	NC control unit battery voltage dropped (0001 warning, 0003 alarm)	Replace the NC battery — with power ON, and back up programs/parameters first
Z70 0002	Absolute position lost	Absolute position basic point data in the NC damaged	Re-initialize the zero point; reload saved abs-position parameter data

Parameter Organization

Mitsubishi parameters are all # numbers grouped by function into blocks that match the setup screens. Parameters marked (PR) in the manual only take effect after a power cycle. Big picture: #1000s are the control, #2000s are the axes, #8000s are yours.

Range	Group	Landmarks
#1000s	Base specifications	#1001 system validation, #1017 rotary axis, #1041 inch/metric, #1121/#1122 edit & display lock, #1128 variable clear, #1195–#1196 macro call enables
#2001–#2100s	Axis specifications (per axis)	#2001 rapid rate, #2007 G1 time constant, #2011/#2012 backlash, #2013/#2014 soft limits, #2028 grid mask
#2201+	Servo (SV001…)	#2201 gear ratio, #2205 speed loop gain, #2218 ball screw pitch, #2225 motor/detector type
#3001+	Spindle (NC side)	#3001 limit rotation speed for gear 00 (slimt)
#4000+	Machine error compensation	#4000 increment method, #4001+10(n-1) basic axis per comp set
#6401–#6496	PLC constants: bit selection	Bit parameters mapped to ladder R registers (R7800–R7847); #6449+ often builder-fixed
#7001–#7300s	Macro list (user macro calls)	#7001+ M-code calls, #7201–#7293 G-code calls G[01]–G[10], #7302 S call, #7312 T call
#7501+	Position switches	#7501 PSW1 axis name, #7502 dog positions
#8000–#8999	Machining parameters (user level)	#8000/#8001 parts counter, #8008 corner decel angle, #8051+ G71 cycle, #8125 G84 S-check, #8211 mirror image, #8301+ chuck barrier
#9001+	I/O parameters	#9001–#9004 data in/out ports and device numbers, #9010 PLC I/O device
#13001+	Spindle drive (SP001…)	#13001 position loop gain (non-interpolation mode)
#16000–#17455	PLC timers & counters	#16000–#16703 timers T0–T703, #17200–#17455 counters C000–C255

Parameters Worth Knowing

A short list of the parameters that answer the questions machinists actually ask — "why does it wake up in inches," "why can't I see O9000," "where's the soft limit." All verified against the M700BM/M700UM manual.

Parameter	Name	What it does
Base specifications
#1017 (PR)	rot	Axis is rotary (1) or linear (0); rotary rolls over at 360°
#1041 (PR)	I_inch	Unit system at power-ON/reset: 0 = metric, 1 = inch
#1078	Decpt2	Commands without a decimal point: 0 = least input increment, 1 = whole 1 mm / 1 inch units
#1121	edlk_c	Edit lock C: 1 = programs O9000–O9999 cannot be opened or edited
#1122 (PR)	pglk_c	Display/search lock for O9000–O9999; setting 1 or 2 also forces #1121 on at power-up
#1128	RstVCI	1 = clear common variables #100–#149 (or #100–#199) on reset
#1195 / #1196	Mmac / Smac	Enable user-macro call from an M command / S command (code tables live at #7001+)
Axis & servo
#2001	rapid	Rapid traverse rate per axis (mm/min)
#2011 / #2012	G0back / G1back	Backlash compensation on direction reversal in rapid / cutting feed
#2013 / #2014	OT- / OT+	Soft limit I in machine coordinates; set both to the same value to disable; #8204/#8205 narrow it at user level
#2205	SV005 VGN1	Servo speed loop gain — higher is tighter until it vibrates; back off 20–30% from the vibration point
Machining & macro
#7001+	M[01] Code …	Macro-call code tables: which M/G/S/T codes call which macro programs (needs #1195–#1196 style enables)
#8000 / #8001	CNT TYPE / WRK COUNT M	Parts counter: which M code (and/or M02/M30) counts a finished workpiece
#8125	Check Scode in G84	Synchronous tap with no S in the block: 0 = use modal S, 1 = alarm P181

Looking Up an Alarm

Alarms display as class + message + a four-digit error number (e.g., M01 Operation error 0102). The manual lists each class in ascending order of that number, so the number — not the message text — is your lookup key. A quick triage routine:

Step	Do this
1	Read the class prefix first — M01 means look at switches/interlocks, P means look at the program, S means look at the drive, Z means look at the control unit.
2	Check the diagnosis screen for operator messages — a `P277` is your own macro's `#3000` alarm text, not a control fault.
3	For servo alarms, note the prefix before resetting: S03 clears with the RESET key, S01 needs an NC power cycle, S04 needs a drive power cycle. Fine detail on servo error numbers lives in the drive unit (MDS series) manual, not the NC manual.
4	No screen nearby? The 7-segment LED on the operation board I/O flashes `A.L` for an alarm (`S.T` for a stop code), then shows the details in three phases, most-critical alarm per part system.
5	If the remedy says "correct the sequence program," you're done — that's the machine tool builder's ladder, and the builder's manual takes priority over Mitsubishi's.

Worked Example: Raising and Reacting to Alarms from a Macro

The alarm classes above aren't just things that happen to you — a macro can raise them on purpose. Writing a number to #3000 stops the program with your own message, and the control files it under class P as P277 Macro alarm message (see the Program errors section of the Common Alarms table). Writing to #3006 is gentler: a planned single stop with a message that Cycle Start clears — no reset, no P alarm. The macro below is a tolerance gate you'd drop in after a probing routine: in tolerance it returns silently, near the limit it does a #3006 planned stop so the operator can react, and out of tolerance it raises a #3000 alarm so the cycle cannot continue. When it fires, the operator's lookup path is exactly the triage routine below: the P277 text appears on the diagnosis screen, not in the Mitsubishi alarm manual.

(O8200 - TOLERANCE GATE)
(CALL:  G65 P8200 A<NOMINAL> B<TOLERANCE> C<WARNING BAND>)
(EXPECTS THE MEASURED VALUE IN COMMON VARIABLE #501,)
(LEFT THERE BY THE PROBING ROUTINE THAT RAN BEFORE THIS CALL.)
(NOTE: #501 SURVIVES RESET UNLESS PARAMETER #1128 RstVCI IS SET)
(TO CLEAR COMMON VARIABLES - SEE PARAMETERS WORTH KNOWING ABOVE.)

O8200
(GUARD THE INPUTS FIRST - A MISSING ARGUMENT SHOULD BE ITS OWN ALARM,)
(NOT A CONFUSING DOWNSTREAM P283 DIVIDED-BY-ZERO OR A BAD COMPARE.)
IF [#1 EQ #0] GOTO 900 ;            (A = NOMINAL, REQUIRED)
IF [#2 EQ #0] GOTO 900 ;            (B = TOLERANCE, REQUIRED)
IF [#3 NE #0] GOTO 10 ;             (C = WARNING BAND, OPTIONAL)
#3 = #2 * 0.8 ;                     (DEFAULT WARNING BAND: 80% OF B)

N10 #30 = ABS[#501 - #1] ;          (DEVIATION OF MEASURED FROM NOMINAL)

(DECISION LADDER - WORST CASE FIRST)
IF [#30 GT #2] GOTO 910 ;           (OUT OF TOLERANCE -> HARD ALARM)
IF [#30 GT #3] GOTO 800 ;           (IN WARNING BAND -> PLANNED STOP)
M99 ;                               (GOOD PART - RETURN QUIETLY)

N800 (WARNING BAND: STOP AND TELL THE OPERATOR, BUT LET CYCLE START RESUME)
#3006 = 1 (SIZE NEAR TOL - CHECK INSERT) ;
M99 ;                               (OPERATOR PRESSED CYCLE START - CONTINUE)

N900 (ARGUMENT MISSING: RAISE A MACRO ALARM - DISPLAYS AS CLASS P, P277)
#3000 = 101 (NO A OR B ARGUMENT) ;  (MESSAGE TEXT SHOWS ON DIAGNOSIS SCREEN)

N910 (OUT OF TOLERANCE: RAISE A MACRO ALARM - CYCLE CANNOT CONTINUE)
(THIS IS *YOUR* ALARM, NOT THE CONTROL'S: THE SCREEN SHOWS P277 PLUS)
(THE TEXT IN PARENTHESES. A RESET CLEARS IT - UNLIKE AN S01 SERVO)
(ALARM, WHICH NEEDS AN NC POWER CYCLE PER THE RESET TABLE ABOVE.)
#3000 = 102 (SIZE OUT OF TOLERANCE) ;

Two habits worth copying: pick your own #3000 numbering scheme (here 101/102) and keep a crib sheet, because the control only shows the number and your 31-character message — the P277 entry in the manual just says "a macro raised this." And use #3006 for anything an operator is allowed to wave through; reserving #3000 for genuine scrap conditions keeps the alarm history meaningful.

References

Mitsubishi Electric, M700BM/M700UM Series Alarm/Parameter Manual, Mitsubishi Electric Corporation.
Mitsubishi Electric, MDS-D2/DH2 Series Instruction Manual, IB-1501127 (servo alarm detail).