New Mill Build...Can I use LinuxCNC?

You would need 5 volts for the logic power and 8-32 volts for field power. I think 24volts is the most common for field power. It is used for relays, limits switches etc. I'm using the 6i24+7i76 combo but if I was doing it over I would use the 7i76E. Although I put the computer motherboard inside my CNC cabinet and I am using a wireless mouse and keyboard. The monitor and my pendant are the only two things with cords.

I see...since it’s field power and not the logic power can I run it off the same 12v PS that I am using for the fans??

I'd use a separate 24v or 12v supply just to be on the safe side of noise.

Which would also mean if the fans took the 12v PSU out for any reason the rest of the system would be safe, throw in an alarm for the fan PSU and if it goes belly up you can take the action you think it requires, rather than loosing all your field power. But I'm kind of paranoid like that.

I think the guys have set you on the straight and narrow. If you are going to buy a Mesa card for a mill, get the 7i76e and never look back. its just so superior to a BOB on a 7i92

Regarding the power supplies, you don't need the extra 5 volt supply. there is a switch that lets it get the 5V logic power from the field power. You only need the 5v power if you are adding daughter cards to the two 25 pin connectors (which you won't). I wasted my money on this.

Peronally I would buy a small (2 amp or so) din rail power supply from Meanwell or similar for field power. It will only cost you $40 or so. 24 volt gets you up into industrial quality system and significantly reduces the impact of any electrical noise because it needs a much greater voltage drop to trigger a false reading. I used a big 7 amp supply which was also a waste of money!

But if you have a 12 volt power supply now, you can give it a go if you are really short on cash.
The D version is used if you are retrofitting an existing machine with active low I/O. But for a new build don't buy it.
Also when you buy it, Mesa have a cool little bus bar that has two banks of 12 common connections. Get 1 or 2 of them. And also they have some nice din rail standoff mounts. You need 5 of them and the bus bars can also use them so you need to buy a few (they come in packs of 2.

I know I'm spending your money here but I'm just passing on what I've learnt by wasting my money!

Finally, check out Norberts amazing connection sheet for the 7i76e. Just read on a bit to get the bug free one.

forum.linuxcnc.org/27-driver-boards/3191...-sheet?start=0#85072

Yup that VFD will work with Mesa 7i92 to it's full speed, it will also work with a parallel port but not up to full speed, most probably as most of the parallel ports in the last 15 years do 3.3V, not 5V.
And you can use some "arduino relays" to do the ON/OFF and direction change on the spindle, they are about 3$ each or in groups of 4 or 8.
Since you have 3 drives that will need 6 pins plus 1 for enable (might not be enough to drive 3 drives), so that leaves 5 outputs, 2 or 3 for the spindle, so enough outputs, and you can do all limit and home switches to 1 input leaving 4 more for probe or something else.
You can remove the BOB or parallel port at any time in the future and just plug the 7i92, the difference is with that BOB you will be limited to around 10000 pulses per second, directly with parallel port from 20000 to 50000 depending on how god the latency on the PC is, and with the Mesa it can do up to 10 million pulses per second. That is very nice if you use a lot of microstepping on the drives so the motors work much smoother.
Again, the best solution would be 7i76E, and yes you can use the 12V for the field power, the same one powering the vents.

tommylight wrote: Again, the best solution would be 7i76E, and yes you can use the 12V for the field power, the same one powering the vents.

And you could even use one of the analog inputs to monitor the voltage on the fan...