MESA card - what difference between voltages

Hi, all.
We bought out first mesa card 7i92m + 7i76.

I didn't catch up, what difference between Vin and Field voltage. I can make it separate with jumper.
Cards will operate servo drivers with Step/dir signals of 5V, but other Enable inputs will be 24V.

Explaine me please this difference. What should I chouse?

if you are using 24V you can tie VIN and field power together

step/dir signals are always 5V

You typically only use separate field power and VIN when you need 5V field outputs/inputs

Thanks for your answer, PCW. To Vin I always need to wire 24V? What this input meens?

VIN supplies the isolated side regulator and can be 8V to 32V
so if field power is between 8V to 32V you can tie VIN to field power

If you have 5V field power, ( or firmware that allows field power to be turned off )
VIN must come from another source.