Working documentation

This page is generated from the project's working notes. It records a real retrofit in progress, corrections included. Anything marked 🔴 or ⚠️ is unresolved or carries a caveat - read those before acting.

The spindle and its inverter - the complete interface

2 September 2026. Read from wiring diagram sheet 5, INVERTER (drawn by Z.C., not F.S.). This supersedes the reference table in CLAUDE.md §9, which was worked out for the Masso plan and lists parameters rather than wiring.

Drive: Yaskawa VS-606V7CC 47P5, 7.5 kW, part 025YAS0015. Motor: HSD M200 electrospindle, 8 kW, 24,000 RPM, connector -AM-PM 999COB0026 CONN. MOTORE HSD.

Control terminal wiring

Terminal	Sheet label	Wired to
FR	SPEED REF 0-10V	-R6 divider network (330 kohm and 2.5 kohm), fed from CONN.S pins 15 and 8, conductors marrone and bianco, referenced to MASSA C.N.
FS	+12V 20mA	-R6
FC, COM		-R6, wires 23 and 24
SC	COM	-C 32, -STRI
S1	FWD RUN/STOP	wire A221, from 25.5
S2	REV RUN/STOP	wire A222, from 25.6
S3	EXT. FAULT	wire 56, via -QFRI contact
S4	RESET	wire 58, via -SB15
P1, PC	RUNNING photocoupler out	wire 931 to -OPT1 NPN-PNP converter, then E130 to 19.1
P2, PC	ZERO SPEED photocoupler out	wire 930, to 6.5
MA, MB, MC	DEFECTIVE CONTACT OUT	wires 19 and 20, to 13.8
AM, AC	ANALOG OUT	monitor output
L1,L2,L3,E	POWER SUPPLY	via -KMI, from -QFINV (17-23 A, set 20 A)
B1, B2	BRAKE RESISTOR UNIT	via -QFRI (6-10 A, set 6.5 A) to -R2, 30 ohm 1300 W
U,V,W	MOTOR	through -L1 common-mode choke (3 turns), then 4X2.5 sch screened cable, U3/V3/W3 to 6.0

🔴 The analog speed reference

-R6 is the SPINDLE kit from Tecnos (025TEC0027, KIT SPINDLE LUNGO + CAVI, sheet 5.1). It is a resistor divider plus cable that takes the CNC's analog output and conditions it for the VFD's FR 0-10 V input, with FS (+12 V, 20 mA) as the reference rail.

The CNC end arrives on CONN.S, pins 15 and 8, brown and white, with MASSA C.N. as the ground.

That identifies the fourth 15-pin D-sub in the device list: CONN.S (025ZAN0020, CONNETTORE VASCHETTA 15PIN MASCHIO, sheet 5.8) is the spindle connector, alongside CONN.X, CONN.Y and CONN.Z for the axes.

✅ Resolved 2 Sep 2026 - R6 is a spindle speed override

Read from a zoom of the -R6 block plus SGM page 5.

-R6 is a 2.5 kohm potentiometer in series with a 330 kohm resistor, mounted in the pendant, feeding the VFD's FC / FR / FS on wires 23 and 24 plus the bianco and marrone conductors. The CNC's analog pair arrives from CONN.S pins 8 (bianco) and 15 (marrone) on -R6:1 and -R6:4.

The ratio settles it. A 2.5 kohm pot in series with 330 kohm across FS (+12 V) would put roughly 90 mV at the wiper - nowhere near the 0-10 V that FR expects. So the +12 V path cannot be the speed source. The CNC's analog output is the source, and R6 scales it.

✅ R6 is a spindle speed override on the CNC's command, the exact counterpart of FR1 on the feed. LinuxCNC's S word will control spindle speed.

⚠️ One measurement confirms it whenever the machine next runs: with a known S commanded, measure FR to FC at the VFD while turning R6 end to end. If the voltage tracks the pot, it is an override.

✅ And the PLC confirms there is no software spindle override competing with it — 6 September

The Tecnos has a second, entirely separate spindle override: a potentiometer read on the analog input VIN_ANALOG1, giving a software trim. It is disabled on this machine.

;*** SPINDLE DA POTENZIOMETRO (80%-100%)
        IF   FONDOSCALA==0              ;se override da non gestire
             COPY  1000,VCOEFF1_POT     ;forzo coeff. al 100 %
             ...
             JUMP  END_OVER_ANA         ;ed esco

pargen.prm has FONDOSCALA = 0, so the routine exits on its first line with the coefficient pinned at 1000, and MW310.PLC defines that scale as "coeff. override pot. (800-1000)" — 1000 is 100 %, no attenuation.

🔴 So the analog chain from controller to spindle is now completely characterised, end to end, with nothing left in it that is not understood:

CNC analog output  →  -R6 passive divider  →  FR / FC
                   →  n011 × n060 / 100  =  0-400 Hz

Stage	Status
Software spindle override	✅ disabled — FONDOSCALA = 0, coefficient forced to 100 %
-R6	✅ passive, in the output path, proved by the 2.5 k / 330 k ratio
VFD gain and bias	✅ factory — n060 = 100 %, n061 = 0 %
Result	0-10 V → 0-400 Hz, 40 Hz per volt, with a floor at 104 Hz from n034

✅ Nothing scales the spindle command anywhere between LinuxCNC's analog output and the motor except things now written down.

For the retrofit: the VFD wants 0-10 V on FR against FC. A Mesa analog output is +/-10 V. The R6 network can be kept (retaining the manual override, which is a genuinely useful feature) or bypassed and FR driven directly. Either way, check against the VFD's n003/n004 settings before connecting.

Three cross-references that confirm the I/O map

The sheet's own wire references decode against MW310.EQU:

Drawing reference	Decodes to	MW310.EQU
A221 from 25.5	Sheet 25 = UF3, point 5 = OF.21	OF_MARCIA_INVERTER ("INVERTER 1 ON") ✅
A222 from 25.6	Sheet 25 = UF3, point 6 = OF.22	OF_INV_INVERTER ✅
E130 to 19.1	Sheet 19 = IF4, point 1 = IF.25	IF_VEL_RAGG ("INVERTER 1 ON") ✅

AUS n = OF.n is proven by this sheet, independently of the output sheets themselves. Combined with the EIN n = IF.n proof from sheet 16, the whole symbolic map now transfers to physical terminals with no toggling and no LED photography.

🔴 A VFD fault trips the emergency chain

MA/MB/MC, the inverter's fault relay, runs on wires 19 and 20 to 13.8, which is relay -KA4. Sheet 16 shows KA4's contact feeding EIN8, the EMERGENZA TERMICI input (IF.8).

So an inverter fault drops the emergency chain in hardware. This is a real interlock and it must survive the retrofit.

🔴 Sheet 6 - the spindle motor contactor and the ZERO SPEED interlock

Sheet 6, RESET PANTOGRAFI, carries the motor itself:

• -M200, PANTOGRAFO 1 C.U. / ROUTING MOTOR, 8 kW, 18 A, 24000 g/min - the HSD electrospindle. Fed from the inverter output U3/V3/W3 plus screen, through -KM200, to =BM+X5 terminals -PM 4/6/8.
• -MV200, VENT. PANT. 1 - the spindle cooling fan, single phase on -X5 15 and -X5 16.

The contactor coil circuit:

OF.48 (wire 42, from 28.8) -> -OPT2 solid-state relay -> 105 -> KM200 aux 13/14 -> 106 -> KM200 coil -> wire 3
                                       ^
                        OPT2 input: wire 14 and wire 930
                        930 = the inverter's ZERO SPEED output (from 5.1)

KM200 is a mechanically latched contactor with separate set and reset coils (Siemens 3TF3500 with a 3TX4090-0GF3 latch). Sheet 28 shows OF.48 driving the set coil (A1/A2) through wire A248 from rail 2A. Sheet 6 shows the reset path (E1/E2) running through -OPT2, whose input is the inverter's ZERO SPEED.

So OF.48 closes the contactor on command, and it only opens once the inverter reports zero speed. That is the correct direction for the interlock: it prevents breaking an 8 kW motor circuit under load.

That answers what ZERO SPEED (wire 930) is for: it is not a PLC input, it is a hardware interlock stopping an 8 kW motor contactor from making or breaking under load. It appears nowhere in MW310.PLC, so it would have been invisible to anyone working from the software alone.

🔴 This interlock must be reproduced. Under LinuxCNC, OF.48 still switches KM200, but the zero-speed gate has to stay in hardware.

It also confirms AUS n = OF.n a third time: 42/28.8 is sheet 28 (UF6) column 8, which is OF.48.

What the retrofit needs from this sheet

Signal	Direction	Where it goes now	Retrofit
Speed reference	out	CONN.S 15/8 to -R6 to FR	Mesa analog output, via or around -R6
Run forward	out	OF.21 via UF3	Mesa output on the ribbon
Run reverse	out	OF.22 via UF3	Mesa output on the ribbon
At speed / running	in	P1 via -OPT1 to IF.25	Mesa input on the ribbon
Zero speed	in	P2, wire 930, to -OPT2	Not a PLC input - a hardware gate on the KM200 coil. Keep it
Drive fault	in	MA/MB/MC to KA4 to IF.8	Leave hardwired
Contactor engaged	in	KMI aux to IF.16	Mesa input on the ribbon

| Spindle contactor | out | OF.48 via UF6, gated by -OPT2 | Mesa output on the ribbon, gate stays hardwired |

Related

• device-list.md - -R6, -R2, -U1, CONN.S part numbers
• power-distribution.md - the supply chain feeding the inverter
• CLAUDE.md §9 - VFD parameter settings for external control (n003, n004, n011, SW2)

---

Reading the VFD — the digital operator

5 September 2026. From Spindle VFD yaskawa-606v7.pdf on Drive, read directly. The keypad is a JVOP-140.

🔴 The one rule: never change n001

n001 is the constant access level, and it is the first thing you land on when you enter programming mode. Its settings, from the manual:

n001
0	Only n001 can be set — but n001 to n179 can all still be READ
1-4	Progressively unlocks n049 / n079 / n119 / n179 for setting
6	🔴 Clears the fault history
12, 13	🔴 INITIALIZE — wipes every constant in the drive

✅ You do not need to unlock anything to read. Even at n001 = 0 the manual is explicit that all constants can be referred to. So there is no reason to touch n001 at all, and two very good reasons not to.

The keys

Key
DSPL	Steps through the function LEDs: FREF → FOUT → IOUT → MNTR → F/R, and to PRGM
∧ / ∨	Change the constant number, or the data value
DATA/ENTER	On a constant number, shows its data. On data, writes it
RUN	Starts the motor
STOP/RESET	Stops the motor; resets a fault

⚠️ DATA/ENTER is both "view" and "write" on this drive — unlike the servo drives, where viewing and writing are different actions. That makes the read procedure more delicate, not less.

Reading a constant, safely

1. Press DSPL until the PRGM LED (red) is lit    -> shows n001
2. ∧ / ∨ to the constant you want                -> e.g. n011
3. DATA/ENTER                                    -> shows its VALUE
4. Write the value down
5. Press DSPL to leave                           <- NOT ENTER

🔴 Back out with DSPL, never with a second DATA/ENTER. And never press ∧/∨ while a value is on screen — the display blinks while a value is being changed, which is your warning.

What to read

Constant	Why it matters
n002	Control mode. 0 = V/f (factory), 1 = vector
n003	Run command selection — where the start signal is taken from
n004	Frequency reference selection — where the speed reference is taken from
🔴 n011	Max. output frequency. The top of the scale
n012-n017	The rest of the V/f pattern
n018	Accel/decel time unit
n019-n022	Accel and decel times — the spindle's ramp
n033, n034	Frequency reference upper and lower limits
n036	Motor rated current
🔴 n060	Analog frequency reference GAIN — % of n011 at 10 V input. Factory 100%
🔴 n061	Analog frequency reference BIAS — % of n011 at 0 V input. Factory 0%
n050-n056	Multi-function input selection 1-7 — what terminals S1-S7 do

🔴 n011, n060 and n061 are the spindle's Pn300

The analog speed reference arrives on terminals FR and FC — the same pair spindle-vfd.md identified for the -R6 override check. The manual gives the mapping:

frequency at 10 V  =  n011 × n060 / 100
frequency at  0 V  =  n011 × n061 / 100

So those three constants convert LinuxCNC's analog output into spindle RPM, exactly as Pn300 does for the servo axes. Read them before assuming anything — the servo drives all turned out to be off the factory default, and there is no reason to expect the VFD to be different.

Two monitors worth knowing about

The U- monitors are read-only and cannot change anything:

U-06 / U-07	Live input and output terminal status. A free way to watch the VFD's own I/O without a meter
U-09	Fault history — the last four faults. Worth capturing before anything else is disturbed

U-09 shows a four-digit code: the leftmost digit is the order (1 = most recent), the three on the right are the fault. Worth recording — it is a free history of what this spindle has been unhappy about.

---

🔴 Full constant capture — 6 September 2026

Grant walked the whole constant list on the JVOP-140 keypad. Recorded verbatim below, before any decoding, because the transcription is the irreplaceable part and the interpretation can always be redone.

⚠️ Read one at a time off a four-digit display. Treat as authoritative but re-read anything a later observation contradicts.

No.	Value		No.	Value		No.	Value		No.	Value
001	4		067	1.00		107	.443		141	50
002	0		068	100		108	10.59		142	12
003	1		069	0		109	150		143	1
004	2		070	0.10		110	33		144	0
011	400.0		071	100		111	0.0		145	0.5
012	380.0		072	0		112	2.0		146	0.2
013	200.0		073	0.10		113	0		149	2500
014	100.0		074	100		115	0		150	0
015	190.0		075	0		116	0		151	0
016	1.5		076	0.10		120	0		152	0
017	10.0		077	0		121	0		153	0
018	0		078	0		124	624		154	2
019	2.5		079	10		125	0		155	0
020	2.5		080	3		126	0		156	10
021	10.0		081	2		127	624		157	0
022	2.0		082	0		128	0		158	30
033	100		083	0.00		129	1.00		159	120
034	26		084	0.00		130	1.0		160	16
035	20		085	0.00		131	1.0		161	10
036	18.0		086	0.00		132	0.00		162	5
050	1		087	0		133	0		163	1.0
051	2		088	1715		134	100		164	0
052	21		089	60		135	0.0		165	0
053	5		090	0.7		136	0		166	0
054	6		091	0.0		137	0		167	0
055	7		092	1		138	1.0		168	0
056	10		093	200		139	0		169	0.0
060	100		094	200		140	145.4		175	1
061	0		095	0.00					176	rdy
062	0.50		096	2					177	0
n064	0		097	0					178	1.SrP
065	0		098	200					179	0103
066	0		099	0.3
			100	0
			101	2.0
			102	150
			103	1.0
			104	0.3
			105	43.9
			106	3.2

⚠️ Three entries are not numbers: 176 reads rdy, 178 reads 1.SrP, 179 reads 0103. Recorded exactly as displayed. These are very likely read-only status or version displays rather than settable constants — being confirmed against the manual.

⚠️ 064 was recorded with a leading n where the rest of the walk was bare. Almost certainly a transcription artefact, not a different kind of item.

⚠️ Gaps in the numbering — 005-010, 023-032, 037-049, 057-059, 063, 114, 117-119, 122-123, 147-148, 170-174 were not recorded. Either the drive skips them or they were passed over.

✅ The spindle scaling is answered, and it is the clean case

This page has carried the question since 2 September: what converts an analog voltage into spindle speed? The three constants that decide it are now read, and the formula was already recorded above:

frequency at 10 V  =  n011 × n060 / 100
frequency at  0 V  =  n011 × n061 / 100

Constant	Reading
n011 max output frequency	400.0 Hz
n060 analog reference gain	100 %	✅ factory default
n061 analog reference bias	0 %	✅ factory default

So the reference scale is 0-10 V → 0-400.0 Hz. Exactly 40.0 Hz per volt, no offset.

✅ This is the opposite of what the servo drives turned out to be. All three SGDH axes had a Pn300 off the factory value (475, 477, 500 against a default of 600), which is why reading them mattered. The VFD's gain and bias are both untouched, so LinuxCNC's analog output can be scaled by arithmetic alone with nothing hidden in the drive.

🔴 What is still needed is the frequency-to-RPM conversion — the motor's pole count, off the nameplate. 400 Hz on a 2-pole motor is 24000 rpm; on a 4-pole it is 12000. Nothing captured so far settles it, and it is a nameplate photograph, not a parameter read.

The V/f pattern is a textbook two-slope curve

Constant	Point	Reading
n016 / n017	minimum frequency / its voltage	1.5 Hz / 10.0 V
n014 / n015	mid frequency / its voltage	100.0 Hz / 190.0 V
n013 / n012	base frequency / max voltage	200.0 Hz / 380.0 V
n011	max output frequency	400.0 Hz

✅ The mid point sits exactly on the line. 190 V at 100 Hz and 380 V at 200 Hz are both 1.9 V/Hz — the mid-frequency pair adds nothing, it just lands on the straight line between minimum and base. Whoever set this drive up entered a linear V/f and let the mid point fall where it fell.

Two regions, and the split is at 200 Hz:

| Below 200 Hz | Constant torque. Voltage rises with frequency at 1.9 V/Hz | | Above 200 Hz | Constant power. Voltage is capped at 380 V while frequency doubles to 400 |

⚠️ A boosted low end. 10.0 V at 1.5 Hz is 6.7 V/Hz, three and a half times the linear slope — ordinary torque boost to get a spindle turning from rest.

🔴 The constant-power region matters for the retrofit. Above 200 Hz the spindle loses torque in proportion to speed. Any feeds-and-speeds work has to know that the top half of the speed range is not the same machine as the bottom half.

---

The decode — read against the manual, 6 September

🔴 n001 = 4 — the drive is wide open

n001 is the access level, and the manual's table is:

n001	Can be set	Can be read
0	n001 only	n001-n179
1	n001-n049	n001-n049
2	n001-n079	n001-n079
3	n001-n119	n001-n119
4	🔴 n001-n179	n001-n179
6	clears the fault history
12, 13	🔴 initialize

Factory default is 1. This drive is at 4 — every constant in it is editable from the keypad.

⚠️ That changes the risk of the read procedure, and this page previously understated it. The earlier advice was "you do not need to unlock anything to read, so never touch n001." True, and still the right advice — but it left the impression the drive was locked. It is not. DATA/ENTER on a value writes it, and there is nothing standing in the way. Back out with DSPL, never with a second DATA/ENTER, and never press ∧/∨ on a value display.

⚠️ Setting n001 to a lower level would protect the drive, but that is a write to a working machine and it is Grant's call, not something to do in passing.

✅ The interface is confirmed, end to end

Three constants describe how this VFD is commanded, and all three match what the wiring schedule says:

Constant	Reading	Meaning
n002 control mode	0	V/f control, not vector	✅ default, and consistent with the V/f pattern being populated
n003 run command	1	🔴 From the control circuit terminals	not the keypad — S1 forward, S2 reverse
n004 frequency reference	2	🔴 Voltage reference, 0-10 V	the FR/FC pair

✅ Run from terminals, speed from an 0-10 V analog input. That is exactly the interface mesa-wiring-schedule.md assumes, now confirmed from the drive's own memory rather than inferred from the drawing.

🔴 The spindle has a hard speed floor at 26 %

This is the finding with the most consequence for the retrofit, and nothing else would have revealed it.

Constant	Default	Reading
n033 frequency reference upper limit	100 %	100 % ✅
n034 frequency reference lower limit	0 %	🔴 26 %

n034 is not at its default. 26 % of 400.0 Hz is 104 Hz, and the drive will not go below it — whatever reference voltage arrives, the spindle floors there.

✅ And this corroborates the pole count. A 2-pole motor at 400 Hz is 24000 rpm, and 104 Hz is 6240 rpm. A 24000 rpm ceiling with a ~6000 rpm floor is the standard envelope for a high-frequency router spindle — the floor exists because these spindles need airflow and bearing speed to stay cool. On a 4-pole motor the numbers would be 12000 and 3120, which fits far less naturally with a 200 Hz base at 380 V.

⚠️ Still to be settled by the nameplate, but the 26 % floor is now a second line of evidence pointing at 2-pole / 24000 rpm.

🔴 LinuxCNC must know about this floor. A commanded 3000 rpm will produce 6240 rpm at the tool. That is a crash-or-burn difference on a small cutter, and it is invisible unless you know the constant is there.

🔴 S3 is an emergency stop, not the external fault the drawing labels it

The seven multi-function input terminals decode as:

Constant	Terminal	Reading	Function
n050	S1	1	Forward run (2-wire)	✅ default
n051	S2	2	Reverse run (2-wire)	✅ default
n052	S3	21	🔴 Emergency stop fault (NC contact input)	not default — default is 3, external fault
n053	S4	5	Fault reset	✅ default
n054	S5	6	Multi-step speed reference 1	✅ default
n055	S6	7	Multi-step speed reference 2	✅ default
n056	S7	10	JOG command	✅ default

Six of seven are factory. S3 is the one that was changed, and it was changed to a safety function.

⚠️ The wiring sheet labels S3 EXT. FAULT. The drive does not agree. It is programmed as emergency stop, NC contact — the contact must be closed for the drive to run, and opening it trips a fault rather than an alarm.

✅ And the wiring says why. From the terminal table above: S3 is wire 56, fed via a -QFRI contact — and -QFRI is the circuit breaker protecting the braking resistor. So if the brake resistor's protection trips, the VFD is emergency-stopped. That is the correct design: you must not keep decelerating a 24000 rpm spindle into a resistor that has just been disconnected.

🔴 For the retrofit: this input has to stay closed or the spindle will not run, and it is a safety interlock, not a nuisance signal to bypass.

✅ A braking resistor is fitted — proved twice

n092 (stall prevention during deceleration) reads 1, against a default of 0. The manual's note on that value:

"Not provided (set this when a braking resistor is mounted)."

✅ And the wiring schedule on this page already had it independently: B1/B2 → BRAKE RESISTOR UNIT, via -QFRI to -R2, 30 ohm 1300 W.

Two sources, one from the drive's memory and one from the drawing, agreeing that this spindle has dynamic braking. That is how a 24000 rpm spindle stops in a workable time, and it is a component that must survive the retrofit — along with its breaker and the S3 interlock above.

The drive was commissioned properly, and set up to work hard

Constant	Default	Reading
n080 carrier frequency	4	3	7.5 kHz instead of 10 kHz — quieter switching, cooler drive
n081 momentary power loss ridethrough	0	2	🔴 rides through a brief outage and restarts, with no fault output
n082 automatic retry attempts	0	0	✅ no retries on a fault
n093 stall prevention during accel	170 %	200 %	raised to maximum
n094 stall prevention during running	160 %	200 %	raised to maximum
n096 overtorque detection	0	2	🔴 detected at constant speed, and the drive STOPS
n098 overtorque level	160 %	200 %
n099 overtorque time	0.1 s	0.3 s

🔴 The spindle stops itself on overtorque — 200 % for 0.3 s. On a router that is stall and crash protection, and it is a behaviour LinuxCNC will inherit whether or not it knows about it. Worth knowing before the first unexplained mid-cut stop.

⚠️ n081 = 2 means a brief power dip does not raise a fault; the drive rides through and restarts. Combined with n003 = 1 (run command from terminals), the spindle restarts if the run signal is still held. That is a real consideration for the safety design — whatever LinuxCNC does with the run signal after a power blip decides whether the spindle comes back on its own.

✅ The motor constants were entered by hand

The VS-606V7 has no auto-tuning routine — the manual has no such function. So n105-n112 were typed in from a nameplate or a motor test report:

Constant	Reading
n105 torque compensation iron loss	43.9
n106 motor rated slip	3.2 Hz	1.6 % at a 200 Hz base — a low-slip high-speed motor
n107 line-to-neutral resistance	0.443 Ω
n108 motor leakage inductance	10.59 mH
n109 torque compensation voltage limiter	150	✅ default
n110 motor no-load current	33 %
n111 slip compensation gain	0.0	✅ V/f default
n112 slip compensation time constant	2.0	✅ V/f default
n036 motor rated current	18.0 A

Somebody sat down with the motor's data and commissioned this drive. ✅ These four measured values are the motor's fingerprint — if the spindle motor is ever swapped or the drive replaced, they are what makes the new pairing behave the same.

✅ There is a free spindle-speed feedback signal available

Constant	Reading	Meaning
n065 monitor output type	0	Analog, not pulse
n066 multi-function analog output	0	🔴 Output frequency
n067 analog monitor gain	1.00	✅ unity

Terminal AM-AC puts out an analog signal proportional to actual output frequency, at unity gain. The wiring schedule lists AM/AC as ANALOG OUT — monitor output, with no destination given, so the Tecnos appears never to have used it.

✅ LinuxCNC could. One pair of wires into a Mesa analog input gives real spindle-speed feedback rather than assuming the commanded value took effect. Worth considering when the field wiring is being planned, since the cabinet will be open anyway.

What rdy, 1.SrP and 0103 are

All three are exactly what they looked like — not settable constants:

	Reading
n176 constant copy function	rdy	✅ READY / idle. The keypad's parameter copy tool, sitting doing nothing. Its other states are rEd, CPy, vFy, vA, Sno
n178 fault history	1.SrP	🔴 read-only. Format is order digit + 3-character code, so this is fault 1 — the most recent
n179 software version	0103	✅ read-only. The lower four digits of the software number

🔴 And the most recent fault fits the S3 finding exactly

SrP is not in the manual's fault list. The closest code that is — and the only close one — is STP, which the manual gives for operator function stop and for emergency stop. A seven-segment T is routinely misread as r.

✅ STP is precisely the fault an open S3 produces, given n052 = 21 sets that terminal to emergency stop fault. The programmed function and the recorded fault agree.

⚠️ Inferred, not proven — the segment pattern should be checked on the unit rather than trusted from a transcription. But it is coherent, and an emergency stop is entirely ordinary on a machine that has been powered up and down repeatedly with breakers off.

⚠️ Which constants can be changed while running

The manual marks these in bold in its appendix as live-changeable. Everything else in n001-n179 requires the drive stopped, and includes every constant discussed above except the analog scaling:

n019-n022, n024-n032, n041-n044, n060, n061, n062, n067-n076, n103, n106, n111, n120-n127, n129-n135

✅ n060 and n061 — the analog gain and bias — are live-changeable. So if the spindle scaling ever needs trimming during commissioning, it can be done with the drive running. That is genuinely useful.

🔴 n035 = 20 — the display is in r/min, scaled by a pole count

The manual has three setting bands for n035, not two, and the middle one is the interesting one:

n035	Display unit
0	Hz — 0.01 Hz below 100 Hz, 0.1 Hz above
1	Per cent of n011
2-39	🔴 r/min — and the value itself is used as the pole count
40-3999	Arbitrary user scaling

"Setting in units of 1 r/min: r/min = 120 × Frequency reference (Hz) / n035 (Set the number of motor poles for n035)"

So this drive displays speed in r/min, computed as 120 × f / 20 — that is, 6 × frequency. At 400 Hz the keypad reads 2400.

⚠️ Which is worth knowing before reading anything off the keypad. FREF, FOUT, U-01 and U-02 are all in these units. They are not Hz and — as below — they are probably not real rpm either.

🔴 Taken literally, n035 = 20 says a twenty-pole motor. That does not fit.

A 20-pole motor at 400 Hz is 2400 rpm, and at the n034 floor, 400 rpm. That is a low-speed high-torque machine, and it sits badly against everything else on this drive: 380 V at a 200 Hz base, 18 A, 3.2 Hz rated slip. Those are the numbers of a high-speed spindle.

Three readings, and the nameplate decides between them:

🔴 A deliberate ÷10 display trick	The manual caps the r/min display at 9999. A 2-pole motor at 400 Hz is 24000 rpm — it cannot be displayed at all in r/min units, and the keypad is only four digits. Setting the pole count to 20 instead of 2 divides everything by ten and gives 2400, which fits. This is the reading that explains why anyone would enter 20
A genuine 20-pole motor	2400 rpm maximum. Possible, but inconsistent with the rest of the drive's setup
A leftover	Carried in from another machine or another motor and never corrected

✅ If the ÷10 reading is right, the keypad shows tens of rpm — 2400 on the display means 24000 at the tool, and the n034 floor displays as 624 meaning 6240.

✅ n124 and n127 are explained by n035 — and they are dead values

Both read 624, which looked impossible against a stated range of 0.00-400.0 Hz. The manual resolves it:

"The frequency reference constants and monitor display data for which this selection of unit function is valid, are stored in the inverter in units of Hz. The units are converted as follows: Setting/Display ← Constant n035 ← Frequency reference constants"

n120-n127 are named explicitly as constants the n035 conversion applies to. They are stored in Hz and displayed in the converted unit. So:

624 displayed  ÷  6  =  104 Hz stored      ← legal, and inside the range

🔴 And 104 Hz is exactly the n034 lower limit — 26 % of 400.0 Hz. The two oddities in this capture turn out to be the same number seen twice. ✅ Each confirms the other: n035 really is doing its conversion.

⚠️ Correction — 624 is not a setting. It is the floor the drive imposes.

6 September, from Grant at the keypad: "When I went into them they were not on 624 however they somehow changed to 624 and I could not change them back."

An earlier version of this page said someone had parked these references on the minimum speed. Wrong. Nobody set them. The manual gives the settable range of a frequency reference as bounded by the limit constants:

Setting range: "min{120/(Fmax) × Frequency reference lower limit (n034) ~ 120/(Fmax) × Frequency reference upper limit (n033))/n035 …}"

🔴 The lower limit n034 clamps the frequency references themselves, not just the analog input. With n034 = 26 %, 104 Hz — 624 in display units — is the lowest value any frequency reference on this drive is allowed to hold.

So what happened is a display clamp. These constants almost certainly still hold their factory default of 0.00 Hz, which became illegal the moment somebody raised n034 to 26 %. Opening one shows the nearest legal value instead, and ∨ cannot go below it because there is nothing below it to go to.

✅ And it does not matter. As established below, S5-S7 are unwired and frequency references 9-16 need four multi-step bits — n124 and n127 can never be selected by anything on this machine. Whether they now hold 0.00 Hz or 104 Hz has no effect on how the spindle behaves.

⚠️ Restoring them is not worth doing. It would mean lowering n034, writing the references, and putting n034 back — three writes to a working drive, one of them to the spindle's safety floor, to change two values nothing reads.

🔴 The real lesson: browsing this drive is not free

A value changed during a read. That is exactly the risk n001 = 4 creates — the drive is wide open, DATA/ENTER is both view and write, and a constant whose stored value has been made illegal by a later change will move on you just from being opened.

🔴 The constant walk is complete and should not be repeated. Everything the retrofit needs from this drive is on this page. The remaining unknowns — n088, the pole count — are not worth another pass at the keypad; the pole count comes off the motor nameplate instead.

⚠️ This also means the capture above records what the drive displayed, which for a clamped constant is not what it stores. Only the frequency references are subject to that clamp, and the only two captured are these — so nothing else in the table is affected.

✅ But nothing can select them — S5, S6 and S7 are not wired

Reaching frequency references 9-16 needs four multi-step speed bits on the input terminals. This drive has two configured (n054 = 6, n055 = 7), and even the 8-step block needs three.

More decisively, the wiring schedule at the top of this page lists no destination for S5, S6 or S7 at all. Only S1-S4 are wired — forward, reverse, the emergency stop, and reset.

✅ So the entire multi-step speed mechanism is inert. No preset speed can ever be selected, and the manual is explicit about what happens then:

"When all multi-function reference inputs are OFF, frequency reference selected by constant n004 becomes effective"

🔴 n004 = 2 — the 0-10 V analog input. It is the only speed path this machine has, and always was. That is a good simplification for the retrofit: there is no hidden preset-speed behaviour to reproduce, and n024-n032 need not be captured.

⚠️ n088 = 1715 is genuinely undocumented

The manual's constant list runs 086 → 089 with no 087 or 088, and the row spacing shows that is a real gap in the printed table, not a dropped line. The strings n087, n088 and 1715 appear nowhere in 176 pages, and neither do the register addresses those constants would occupy. The revision history itemises every constant added across three software versions and never mentions them.

So the drive displayed a value for a constant this manual does not define. It is unexplained, nothing depends on it, and it is recorded here verbatim in case it ever matters.

⚠️ One cheap check if the keypad is ever open again: step up from n086 and see whether N087 and N088 appear at all, or whether the display jumps straight to N089. That says whether the gap is real on this unit's firmware.

✅ None of this disturbs the scaling

n011, n033 and n034 are not in the manual's list of constants the n035 conversion applies to — that list is the frequency references, the jog reference, and the FREF/FOUT/U-01/U-02 displays.

So the analog reference scale stands as recorded: 0-10 V → 0-400.0 Hz, 40 Hz per volt, with a floor at 104 Hz. What changes is only how the keypad reports speed, and what the nameplate has to settle.

What this capture settled

Question	Answer
What converts volts to spindle speed?	0-10 V → 0-400 Hz, 40 Hz/V, gain and bias both at factory
Where does the run command come from?	The control terminals, S1 forward / S2 reverse
Is there anything non-obvious in the drive?	Yes — a 26 % speed floor, an emergency stop on S3, and overtorque stop
Is a braking resistor fitted?	Yes, confirmed by both the drive and the drawing
Is spindle speed feedback available?	Yes, on AM-AC, unused by the Tecnos
Can any preset speed be selected?	No. S5-S7 are unwired, so the analog input is the only speed path
How many motor poles?	🔴 Still the nameplate — and it now settles two things: the real spindle RPM, and whether n035 = 20 is a display trick or a genuine pole count