Help wiring emergency stop on MKS DLC 2.1

Sir,may you help me,how to connect or wiring emergency stop for mks dlc v2.1.,can you share wiring diagram for emergency stop for mks dlc v 2.1, thanks sir ,hope you can helpa me

I would put the emergency stop in the mains circuit.
My second choice would be the DC power to the motors.

1 Like

You can use the “switch” on the mainboard with a NC emergency button.
Just remove the 10a fuse to enable the usage of the switch pins

If youcut the dc power for the motors you will create an back emf spike on your motor drivers and possible on your mainboard.

Better to cut the wires that provide the steppers from signal.
And the cnc motor/laser power
That way the steppers stop running and stay into position
(Also a spike of back emf) but the controllers electronics should handle this much better as they are online

I burned a mainboard + 6 drivers by cutting power once…
Same thing as moving a gantry /steppers by hand when the power is off…
If you do this observe the mainboard…
The leds will go on.
This is an ideal way to drain your bank account!!
The faster you move it the more you wreck

1 Like

IMHO, an emergency switch is there for an emergency, as @donkjr stated.

Cutting the mains is the only safe way for a setup to handle an unknown emergency. Doing otherwise, is making an assumption you know what the emergency will be. If you know what’s going to fail, you can usually prevent it…

If the board or anything else starts to smoke or flame, that’s an emergency and you need to cut the mains.

Even in industry they kill the power to the whole machine.

In a fire department response they cut the mains to the home or building for the same reason.




And you need to be cutting all ac rails; not just one. Eg a Double Pole switch or relay. (triple pole for a 3 phase machine).

Anything else is just a ‘stop’ button, without the ‘emergency’ part…

Edit: At school our lathe and mill had a electrically ‘held off’ mechanical brake that would stop it (almost) instantly; and attract the teachers wrath since it had to be manually reset with a key.

1 Like

We recently covered this in a thread post; I cant seem to find it though.

Do Not simply cut the lines from the stepper drivers to the motors; this will very likely destroy your drivers since they rely on the motor coil inductance being present when active.

1 Like

Cutting mains is cutting the power from a machine… if it is revving at say 3000 rpm it will slowly stop turning…

Normally an emergency stop button STOPS all operations in a machine…
Stop all movement
Stop spindle from turning
Stop lathe from turning etc

For An Mks Dlc32 V2.

The way this is wired (that was the question )
Is cutting the servo/stepper drives
Enable/step signal
For a mill/lathe spindle: cut the signal for rotation/activate the brake

Cutting power to the controller will give z axis that can drop and burn out the stepper drives/mainboard

So if the spindle is burning up, feed more power to the part in flames?

Again assumptions on what/how something is going to fail in an emergency is usually a poor idea …


Generally a mechanical (disk) brake mounted directly on the spindle drive, but well away from the action. This is how big workshop machines do it.

On a DC spindle you can use a relay to short the motor through a suitable dump (aka a big resistor, maybe a big NTC works too).

In both cases and in Peter-Perfect land, the brake must release once the shaft stops. To aid extraction of what remains of one’s hand, I assume.

There are industrial standards for Estops. You can google it if interested.
I read them once and concluded that implementing them cost more than my machine.

1 Like

I have exactly the same request. I would like to add an emergency stop button that is most effective without causing any damage to my board or steppers. What is the solution, in the end? I didn’t quite understand

If you want the simple answer, that came from @jkwilborn:

Then you bring up damage to the board.

It’s the famous answer: “it depends” — it depends on your machine, your power, your goals, how much work besides pure wiring you want to do, and how much you want to spend.

What kind of machine are you controlling with this generic controller? What outcomes do you expect to effectively prevent?

What DC voltage are you using in the machine?

Do you have single phase or multi-phase (including split-phase) power running to the machine?

Have you already bought a particular estop or are you also asking for advice on what kind to buy?

What kind of spindle do you have?

I can tell you that I, personally, on my router, with split-phase 220V power, a VFD, and a three-phase motor, cut both hot mains legs with a 2NC estop.

If you are using single-phase mains and a brushed DC motor, and you are concerned about back EMF from the spindle and/or stopping the spindle faster, you might use an NO/NC estop and engage a large power resistor across the spindle using the NO side, with the single hot leg of mains power going through the NC side. As an alternative to using the e-stop to engage a resistor, you can use a return energy dump to (again!) dump the back-EMF electrically through a resistor, but then it doesn’t need any help from the e-stop, it just senses and shunts back-EMF.

If you have 12V DC you can cut the DC power if you want. If you have 24V you might cut DC power but might have fewer cycles. If you are using 36V you probably don’t want to. In any case, check the switch ratings. AC quenches arcs when passing through 0V so you can switch a much higher AC than DC voltage with the same switch. But I personally prefer to switch the mains power.

What do manufacturers do? The estops that came on on my lathes and my mills just cut mains power, and the spindles coast. This includes my 14x40 engine lathe that might be spinning an 85lb chuck not even counting whatever metal the chuck is holding. That engine lathe also has a foot brake that stops the spindle quickly, and disables the ready contactor, but does not pop the estop.

For damage to stepper drivers: There aren’t a lot of applications that you are going to drive from an MKS DLC are going to see the kind of damage that @giel_bloks ran into where cutting the power is going to kill the stepper drivers. You have substantial inertia for that to happen. I’ve cut mains power to my router carrying a 1.5kW spindle many times during firmware configuration testing, and occasionally in operation, and never lost a stepper driver. I’m using external stepper drivers because the steppers are so large that step sticks can’t supply enough power. I do not use relays there. Just both hot legs of my split-phase mains.

Some of us here can talk through tradeoffs, but ultimately you are making your own decisions about safety. :smiling_face:

I have an idea, I’m not sure if it can be done. I have a Laser CNC, and I use the MKS DLC32 board. I don’t use the Z-axis limit switch in my CNC. Is it possible to use these limit switch as an emergency stop?

If the firmware you are running has an alert / cancel function, you might be able to hook it up to limit switches for out-of-bounds movement to cancel movement and stop.

However, that doesn’t replace the function of an e-stop. An estop’s primary purpose is actual emergencies. And it should be physical, so that software or firmware bugs do not prevent it from working correctly. It can also work for non-emergencies, but that’s secondary to its primary must-work function.

1 Like