Calculate time

You can use DateDiff function here. See examples at http://stackoverflow.com/questions/2633708/date-difference-in-minutes and http://msdn.microsoft.com/en-us/library/xhtyw595(v=vs.84).aspx

so this should work?
var ctrlsource1 = Runner.getControl(pageid, 'Acion.');

var ctrlsource2 = Runner.getControl(pageid, 'Corte');

var ctrldiff = Runner.getControl(pageid, 'Tempo');
function func() {
ctrldiff.setValue(datediff("n",ctrlsource2.getValue(),ctrlsource1.getValue()))

};
ctrlsource2.on('keyup', func);

every VAR function need to be close exept for the total VAR "ctrldiff" at the end, so should be:

if you add more "ctrlsource 3, 4, 5, etc" VAR need to be close at the end too.

and try replace total line function with this one and see what happen:

at the end is ";}" , not "};"

look here an example:How to calculate values on the fly

Ok, Thank you. I have changed this. Now it´s look like this
var ctrlsource1 = Runner.getControl(pageid, 'Acion.');

var ctrlsource2 = Runner.getControl(pageid, 'Corte');

var ctrldiff = Runner.getControl(pageid, 'Tempo');
function func() {
ctrldiff.setValue(date(ctrlsource2.getValue() / (date(ctrlsource1.getValue()))))

;}
ctrlsource1.on('keyup', func);

ctrlsource2.on('keyup', func);
But dosn't work. The error is "'date' not defined"

There is such function as date() in Javascript and this is why it says "'date' not defined"