@zov:

Some sort of PWM is used to regulate the current through stepper's coils with different supply voltages. TMC2660 has 2 type of PWM not sure which one is used in Duet firmware. Rated voltage is the max voltage that can be applied when driving the stepper in pure voltage mode when current through a coil is limitted by its resistivity (multiply Imax by Rcoil and you get it). BTW how do you check that the driver chip is OK, visually? It is a chance that driver's nMOS switches got short to VIN and/or GND and they fried the coil so it is wise to check driver's chip with a multimeter. PWM in standstill is static for coils in stepper while when fast moving there is constant changing in driving pulse width so many transient events that might provoke the fail (bad electric contacts could give that for example).

i connected another motor to the same driver and it worked. still waiting for my replacement to come.

how do i make sure its not the driver before i fry another motor.

@dc42:

Are you certain that the problem isn't in the crimp connections to the stepper motor wires?

yes I'm certain. it was working fine before.
i extended the wires using solder and heat shrink.

duetwifi is amazing.

this is my first time using it.
but duty and shipping alone exceed the price of controller board.
can i manufacture the board here in India and use it for my printers that i am planning to sell?.

thanks for the help.
there is no logical explanation to say that motor fried because of an increase in speed (from pronterface).
and motor stopped working right after I increased the speed.

what should be the rated voltage for stepper motor if I'm using a 24V supply?
documentation says less than 3V. can someone explain this?

thanks for the information DjDemonD.
stepper driver is working fine.
I want to know what can fry a stepper motor other than current. (current was well below the rated current).
running duet with a 24V supply.
how does a stepper motor run with a 24v and 12v with same rated current? (I have very basic knowledge of motors)

I am setting up duet for the first time.
my machine uses 6 stepper motors.
one y-axis motor 2.3A rated current (ok42sth60-2304a)
I set the current to 1.8A.
it was working fine when I was testing movements,
then I increased the speed from pronterface and tried running it.
it just vibrated and didn't turn. other motors worked fine.
reconnected everything. same problem.

checked the continuity of coils. red and blue wires are not continuous. (fried?)
could increasing the speed cause this?

config.g

; Configuration file for testing Duet Ethernet and Wifi

; Communication and general

M111 S0 ; Debug off

M550 Sculptbot ; Machine name and Netbios name (can be anything you like)

M551 3dparadise ; Machine password (used for FTP)

M552 S1 ; Turn network on

;
M555 P2 ; Set output to look like Marlin

M575 P1 B57600 S1  ; Set auxiliary serial port baud rate and require checksum (for PanelDue)

G21 ; Work in millimetres

G90 ; Send absolute coordinates…

M83 ; ...but relative extruder moves

; Disable Fan 1 thermostatic mode

M106 P1 H-1

; Axis and motor configuration

M569 P0 S1 ; Drive 0 goes forwards

M569 P1 S1 ; Drive 1 goes forwards

M569 P2 S1 ; Drive 2 goes forwards

M569 P3 S1 ; Drive 3 goes forwards

M569 P4 S1 ; Drive 4 goes forwards

M574 X1 Y1 Z0 S1 ; set endstop configuration (all endstops at low end, active high)

;*** The homed height is deliberately set too high in the following - you will adjust it during calibration

M906 X1700 Y1950 Z1700 E1130:1130 I60 ; Set motor currents (mA) and increase idle current to 60%

M201 X800 Y800 Z15 E1000            ; Accelerations (mm/s^2)
M203 X10000 Y10000 Z800 E3600       ; Maximum speeds (mm/min)
M566 X200 Y200 Z20 E20              ; Max Jerk speeds mm/minute

M208 X200 Y200 Z200  ; set axis maxima and high homing switch positions (adjust to suit your machine)
M208 X-2 Y-2 Z-0.2 S1   ; set axis minima and low homing switch positions (adjust to make X=0 and Y=0 the edges of the bed)
M92 X80 Y80 Z1600  ; set axis steps/mm
M92 E418.5:418.5  ; set extruder 0 and 1 steps/mm
M350 X128 Y128 Z128 E128:128   ; set microstepping128

;z probe
M558 P4 X0 Y0 Z1 H8 F200 T5000 R0 ; smart IR Z probe, used for homing Z axis only, dive height 3mm, probe speed 200mm/min, travel speed 5000mm/min, no recovery time
G31 P300 X11.0 Y0.5 Z1.65  ; set threshold and offsets

Thermistors

M305 P0 ; Put your own H and/or L values here to set the bed thermistor ADC correction

M305 P1 X100 ; Put your own H and/or L values here to set first nozzle thermistor ADC correction

M305 P2 ; Put your own H and/or L values here to set 2nd nozzle thermistor ADC correction

M570 S180 ; Hot end may be a little slow to heat up so allow it 180 seconds

; Adjustments for J-heads used as dummy heaters on test rig

M563 P0 D0 H1 ; Define tool 0

G10 P0 S0 R0 X-50 Y0 ; Set tool 0 operating and standby temperatures

M563 P1 D1 H2 ; Define tool 1

G10 P1 S0 R0 X50 Y0 ; Set tool 1 operating and standby temperatures

;M307 H0 A250 C140 D5.5 B1

;M307 H1 A250 C140 D5.5 B0

;M307 H2 A250 C140 D5.5 B0

; Fans

;M106 P1 S-1 ; disable thermostatic mode for fan 1

; Tool definitions

;M143 H0 S135 ; Maximum temperature - Heated bed , default is 125C
;M143 H1 S290 ; Maximum temperature - Right extruder, default is 262C
;M143 H2 S290 ; Maximum temperature - Left extruder, default is 262C

;*** If you are using axis compensation, put the figures in the following command

M556 S78 X0 Y0 Z0 ; Axis compensation here

;M208 S1 Z-0.2 ; set minimum

T0 ; select first hot end

thanks David for a great answer.
I need about 1m extension. its a big machine.
is it even worth trying to place thermocouple daughter board that far away from controller or should I just browse for longer thermocouple (I live in India, its not easy to find custom sized thermocouple)

and also for other electronics, I have right wires, I am going to solder the extensions and heat shrink over it. sounds good to you? I don't know much about electronics.

This is my first time, I am working with a thermocouple and duet wifi controller. I read various forums and I found out extending thermocouple is not advised. I was wondering if I can place the thermocouple board (from duet 3d) somewhere around the thermocouple and extend it's output wires to the duet wifi controller, thermocouple I am using is Ktype thermocouple.

For rest of the electronics, I am connecting the extensions using soldering, should I use male female plugs instead of soldering?