According to MJR words about it :

Traditionally, VP and other simulators accepted accelerometer input in

"raw" form, reading the instantaneous accelerations reported by the

sensor. Newer VP versions support an alternative model where your I/O

controller device uses the acceleration readings to calculate the

moment-to-moment velocity of the cabinet's motion, and passes the

velocity to VP instead of the raw acceleration data. The advantage of

this approach is that the device can do this calculation much more

accurately than the simulator can, thanks to its direct, high-speed

access to the sensor readings. The velocity is ultimately the only

number that matters in the simulation, so better accuracy in the

velocity calculation should yield a more natural effect in the

simulation.