Wiring 7i96 and THCAD

Per the thread title I'm trying to figure out how I'm supposed to wire up the 7i96 and the THCAD and a hypertherm plasma.

Here's a diagram of where I'm at from pulling together bits and peices from various other threads:


I'm pretty confused about the Start and Transfer (arcOK) signals. The start signal is supposed to be 15v but the output on the cards is only at 5v, right? Hypertherm says the arcOK signal is 120vac??? Is my diagram close to correct? A user on the iirc suggested I isolate the transfer signals, how would I do that?

In case you couldn't tell I'm no electrician. So if you wanted to explain things to me like I'm a toddler I would be very grateful . If you wanted to mark up the diagram itself that would be amazing!

Hypertherm manual for reference
www.hypertherm.com/en-US/hypertherm/powermax/powermax45-xp/

[Edit]
While not on this drawing I do realize I would ground the THCAD shield pins.

Also, for THCAD-10 I would want the 40:1 voltage divider setting at the hypertherm for a range of 0 to 8v?

The start wiring looks correct (though the polarity may be wrong)

The 7I96 outputs are switches (rated 0V to 36V 2A max) which is
what the start terminals expect. The outputs are polarized and will
be "stuck-on" if wired backwards.

The transfer output is a relay contact. Assuming you are using a 24V I/O
power supply and common input ground you wiring looks right there also
with the addition of connecting the input common pin on the 7I96 to 24V
common.

PCW wrote:

The start wiring looks correct (though the polarity may be wrong)

The 7I96 outputs are switches (rated 0V to 36V 2A max) which is
what the start terminals expect. The outputs are polarized and will
be "stuck-on" if wired backwards.

The transfer output is a relay contact. Assuming you are using a 24V I/O
power supply and common input ground you wiring looks right there also
with the addition of connecting the input common pin on the 7I96 to 24V
common.

Wow, I'm closer than I thought!

"...Assuming you are using a 24V I/O power supply..." So I was planning to use a 24v psu for the motors, and a 5v psu for the 7i96. Do I need a third power supply for I/O or can I use the same supply as the motors?

[edit] "... The 7I96 outputs are switches ..." Ahhhh, I know I've read that before and I suppose it just didn't really register with me. I get it now! My (limited) experience with electronics is just arduino and esp type stuff so that is a different sort of I/O than I'm used to... I think

[edit x2] Yup, it's in the manual. I've been cramming too much...

Yes you could use the same supply as your motors

Also on the divider 20-1 might be a better choice (~200V full scale)
sine you will never be cutting at more than 200 V

PCW wrote:

Also on the divider 20-1 might be a better choice (~200V full scale)
sine you will never be cutting at more than 200 V

So is 200v full scale something I can find specified in the manual, or is it a figure just known from experience?

its just 10V/(1/20)

Either you misunderstood my question or I have the whole concept lopsided.

What I'm asking is how do i know what the full unscaled voltage could be? The manual said maximum of 16v, I was just assuming that it's then possible for there to be 16*20=320 volts at the torch. Or rather, if I had it set to 20:1 I could potentially see 16v at the thcad which I would assume is no bueno. But your saying I *probably* won't see more than 200v, or definitely wont?

Are there any charts anywhere showing the input variables into the plasma torch vs voltage?

The maximum continuous input on the THCAD-10 is 500V so 16V (or 500V)
is not an issue, what it means is that you cannot read voltages above about
200 (it will just read ~200V with more than 200V plasma voltage)

This is fine since you will never cut at more than 200V, and this actually
increases the usable resolution of the voltage reading.

Ah, so I did have it perfectly lopsided! And I also now remember you telling me this before. It's perfectly clear this time. Thank you very much.

I'm not familiar with the 7i96, but the torch on (12 & 14) looks wrong to me.
The plasma needs 12 and 14 to be connected to start cutting. (ie the torch on switch)
So you would normally use an output to trigger a relay which turns the torch on by joining 12 & 14

I know PCW has suggested you can use the on board spindle on relay on some Mesa cards to turn the torch on instead of an external relay like I used. I'm not sure if this applies to your card and wiring shown. If it does, just ignore me...