successive file into gif animation by gnuplot

plotADC1.gp

#!/usr/bin/env gnuplot
set term gif animate optimize
set output 'ADC1.gif'
do for[i=0:8:1] {
  file = sprintf("ADC1-%03d.dat", i)
  time = sprintf("t=%d-%d[sec]", i*200, (i+1)*200)
  set title time
  plot file w l
}