12V and 5V control board?

@Bari
Maybe I can provide some more info on the topic:
He is using Step/Direction motor drives for stepper motors on a machine he wants to retrofit to linuxcnc. He's been working on figuring out the input and out put signals for the machine since the documentation he's got does not fit his machine.
No decision has been made as to what breakout board or FPGA board to use.

His machine has XYZ , Spindle and a simple rack tool changer.
The old controller uses 16 logic outputs, 8 relay outputs and 24 logic inputs. Not all of those are actually in use but the main hurdle is that the signals are 12V not 5V
So his motor drives expect 12V logic commands (instead of the more common 5V) so he is looking for either a break out board that can provide 12V signals or, since mesa boards can only provide 5V step direction signals, a converter board that is fast enough to convert the 5V Step/Dir signals to 12V.

Since electrical skills are somewhat limited a ready made solution is called for.



The whole tread is over here
forum.linuxcnc.org/38-general-linuxcnc-q...axis?start=20#253061

Hmmm...
First, we need to know if the inputs are active low or active high.
Active low would be easy by adding a transistor on each output from bob/mesa.
Active high would also require adding resistors to each transistor.
As for inputs on bob/mesa, simple resistors will do just fine.

I think I just found a solution:

www.aliexpress.com/item/4000459030365.html

Not sure how fast the optocouplers are on that board but it would be worth a try.


edit:
This one here specifies a "working frequency" of 20kHz, not exactly stellar for a step signal but certainly good enough for everything else.

www.aliexpress.com/item/1005001790613213.html

edit2:
The TLP550 in the original controller are 1Mb/s so the puny 20kHz will probably not do it for the step signal for the drives.
 

If you have already got one maybe you could check if it can output 12V, I didn't think those boards could but if it can then you won't need the other boards.

Measure the voltage on the inputs going to drives, if it is near 12V do not use that board.
The board/bob uses TTL buffer chips rated at 5V +-5%, so anything above that will destroy them.
If the voltage is near 12V at rest, most probably the inputs are active low, so again, transistors or ULN2803 should work just fine.
If the voltage is near 0V, those would be active high inputs, so anything with 5V outputs like that bob will not be able to trigger inputs.
Again, in this case, transistors with pullup resistors should work, just beware that the spindle might stay on when LinuxCNC is not active, so might need another transistor to invert that output/input to spindle drive.