CODE

controller = thisComp.layer("CONTROLLER");
show = controller.effect("Show (seconds)")(1);
fdin = controller.effect("Fade-in (seconds)")(1);
fdou = controller.effect("Fade-out (seconds)")(1);

cycledur = fdin + show + fdou;
numcycles = Math.floor(time / cycledur);
delta = time - numcycles * cycledur;

if (numcycles != index - 2)
0;
else if (delta < fdin)
linear(time, numcycles * cycledur, numcycles * cycledur + fdin, 0, 100);
else if (delta >= fdin && delta < fdin + show)
100;
else
linear(time,numcycles * cycledur + fdin + show, (numcycles + 1) * cycledur, 100, 0);

CODE

controller = thisComp.layer("CONTROLLER");
show = controller.effect("Show (seconds)")(1);
fdin = controller.effect("Fade-in (seconds)")(1);
fdou = controller.effect("Fade-out (seconds)")(1);

cycledur = fdin + show + fdou;
numcycles = Math.floor(time / cycledur);
delta = time - numcycles * cycledur;

if (numcycles != index - 2)
100;
else if (delta < fdin)
linear(time, numcycles * cycledur, numcycles * cycledur + fdin, 100, 0);
else if (delta >= fdin && delta < fdin + show)
0;
else
linear(time,numcycles * cycledur + fdin + show, (numcycles + 1) * cycledur, 0,100);