Help with changing light value of block

I'm playing around with making a mod using MCLink, and I want to make a block that has a controllable light value base on analog input from Arduino. I have a procedure set up that runs every 10 ticks that maps the analog input (0-1023) to the block light value (0-1). It works, but only changes light value when placed. The light also persists even after the block has been destroyed. Here's my code:

double pot_range = 0;
double light_range = 0;
double pot_start = 0;
double pot_end = 1023;
double light_start = 0;
double light_end = 1;
double input = 0;
pot_start = ((double) 0);
pot_end = ((double) 1023);
light_start = ((double) 0);
light_end = ((double) 1);
input = ((double) (CurrentDevice.analogRead((int) 0)));
pot_range = ((double) (pot_end - pot_start));
light_range = ((double) (light_end - light_start));
block.setLightLevel((float) ((((input - pot_start) * light_range) / pot_range) + light_start));

The mapping algorithm is 

output = (input - input_start)*output_range / input_range + output_start;

from https://stackoverflow.com/a/5732117/10942590.