Chargepump

Same situation here, but when I power down the Stepcraft as well, everything's fine. No spinning Dremel (or in my case actually a Proxxon).

For the sake of safety I always switch of the Proxxon when changing the tool or just leaving the machine.

Do you use some USB module or a parallel module?

Ad hoc I can't tell wheather the signal is low active or high active, but I'd simply add a pull up/down resistor to the floating input on the X1 connector.

It is a parallel module. For what I think, (not at the machine right now) it's a active High signal. So, then I can use a 10K PullDown resistor?

Just to make sure ... I mean you have to add the resistor to this connector:

Solid state relays fail on

don't use them...

you need a charge pump system in the same circuit.

charge pump circuit is only safe solution

when 12.5kHz signal is active - A relay is on...

everything else happens down wind of that.

Could you be more specific about a charge pump circuit? How do I implement it?

Charge pump circuit acts like a failsafe - it needs to see 12.5kHz (usually) and it will enable a signal or relay. This only works then if the software is on an reset for CNC control.

closing down the software, loss of communication, disconnection of USB, PC power down will all cause this charge pump signal to stop - and stop the safety relay - and therefore stop the spindle from turning on.

There is no charge pump circuit in the relay module for the spindle on/off circuit. What is happening is when the PC powers down and the STEPCRAFT control board is on - the input / output states of the USB controller or paralell ouutput can change causing the spindle relay to turn on. Equally - on PC power up this can happen to.

We have done this on some machines in specific applications using a UC300. 1 port of the UC300 connects to the STEPCRAFT machine. the other port connects to a breakout card with teh charge pump feature and then safety and M03 relays.

Of course you can use come pull up / pull down resistors etc in the setup to stop the input state from changing but the safest way is the charge pump feature.

Ok, I understood that part.
Now im figuring out how to implement it in my config.
I build a charge pump circuit like Mariss Freimanis. It is working.

But, there are more safety points, than only the spindle. I also want to disable the motors with this circuit.

In the connection diagram for the 15 pin port there is a disable pin on #11. What does this on? Disable the motor drivers?
Does somebody know this?

Not as easy as its all integrated.

Ideally - the chargepump can be used to disable drive power and also the spindle. But as the drives are all integrated then its not so easy.

Just the spindle is enough on the STEPCRAFT.

Thank you.

So I will use the charge pump only for the spindle.
Then I would like to have some advice how to connect;

My spindle is now connected to a solid state relay on pin 13 of the subD 15 port.
So i have it connected to 13 (+5V) and GND.

So, the charge pump relay would be in series with that?
Example: pin 13 -> charge pump relay -> solid state relay?

Solid state relays can fail on... Best not to use them.

Typically - the charge pump relay contacts (NO and then closed when charge pump is active and then open if charge pump is not present) can be used to break the live feed to the spindle. Or the signal to engage the spindle.

So yes - your setup will work.

However - this setup is logic based. It assumes that when the CP knocks off - the CP relay goes to open and the pin 13 signal does not get to the solid state relay and then shuts off.

it assumes when the solid state relay doesn't have a signal then its off..

Its always important to risk assess the worst case scenario...

The above advice is only advice. Any work on AC or even low voltage Dc should always be carried out by a certified electrician :