Hi Andreas,
try setting only the new data to the model, and skip the setting model to lineChart
ie
updateChart: function( ) {
var lineChart = this.byId("myLineChart");
var oModel = lineChart.getModel();
..
var oData = oModel.getData();
oData["modelData"] = callbackData ;
oModel.setData(oData);
jQuery.sap.delayedCall(5000, this, updateChart)
}
hth
jsp