Particle To Emitter Node makes emitter particles from other particle system for the fluid simulation.
Need to set particle size(radius) carefully by base particle density for correct simulation.

Input / VDB Grid:
Input vdb data to make Particle Emitter. You must connect this input for work.

Output / Simulation Data:
output result simulation data.

on/off:
Defines on/off status for this function.

Cell Size (3dsmax world unit):
The size of voxels in the generated VDB Grid. You have to be careful that too small a value consumes more computing time and more memory.

Group ID:
Defines particle group ID.

add Fluid Density:
When checked, add fluid density value to the emitter particles.

Fluid Density:
Defines value of fluid density. Larger value means more dense(heavy weight) fluid.

add Viscosity:
When checked, add viscosity value to the emitter particles.

Viscosity:
Defines value of viscosity. Larger value makes more viscus fluid.