Fijate si te sirve esta función:
Código PHP:
function getElementPosition() {
var offsetTrail = this;
var offsetLeft = 0;
var offsetTop = 0;
while (offsetTrail) {
offsetLeft += offsetTrail.offsetLeft;
offsetTop += offsetTrail.offsetTop;
offsetTrail = offsetTrail.offsetParent;
}
return {left:offsetLeft, top:offsetTop};
}
var pos=getElementPosition.call(document.getElementById('idCampo'));
alert(pos.left);
alert(pos.top);