Q:

How does Cooper send coordinates through the falling sand?

When Cooper tries to communicate the coordinates of the NASA facility to Murph through the falling sand, it's said he's doing it in binary. How does he convert the coordinates to binary?
And it looks like he is simply drawing 0's and 1's in the falling sand. How would that result in a bar pattern as seen on the floor in Murph's room?

A:

This scene is explained quite well what the meaning of the sand is, 'thick is 1, nothing is zero' 
Cooper himself, may either just know the values, since he also deciphered them himself in the past...though it's also possible off screen that TARS converted the values for him, like TARS did for the morse code for the singularity data...As this scene here. 
The sand in the room, or rather, Cooper was able to draw the lines, himself through an anomaly in gravity, or gravity waves, and putting his hand in between, 'stopping' gravity from working in those positions, and the sand falling down. As seen here :)

