5i25 variable frequency output

Time has come to install a new spindle driver on a milling machine. This driver wants a variable frequency to control spindle speed.
The frequency needed is 0 to circa 2kHz.

How do I generate a variable frequency output from a 6i25 board?

Easiest way is with a step generator running in velocity mode

For example if you configure a stepgen in velocity mode and set the step scale to 1
the frequency output equals the velocity setting

Installed the new spindle today. Stepgen in velocity mode was the right thing.