set xrange[0:4096]                                                                                                                                    
set yrange[0:15]                                                                                                                                    

set xlabel "DAC demand in millivolts (inverted i.e. 4096-demand)"
set ylabel "Output voltage from LM2676 current source"

R1 = 10000
R2 = 2200
R3 = 1500          

f(x) = - (R1 * ( 1.2/R2 - ((x/1000.0)-1.2)/R3 ) + 1.2) 

plot f(x) 
!sleep 20

set  terminal png
set output "heater_lm2676_fb.png"

plot f(x)