Mesa 7i76e + pncconf + motion

This is a newbie question I know,

In short, where is the motion calculated when using the Mesa cards (such as in my case the 7i76e), is it within the FPGA on the card or within the linxcnc software application

Is it possible to change the pin setting:

hm2_7i76e.0.stepgen.00.maxaccel

on the fly?
- periodically
- at servo-loop frequency (1khz)

Acceleration and velocity are completely controlled by LinuxCNC

Generally the stepgen maxaccel parameter is set to a number about 25% greater
than linuxCNC will ever request. If you change it so its lower than LinuxCNCs
Acceleration settings in the INI file, you will cause following errors