Hello,

Here is a sample application main window c# and XAML.  We want to set the X axis to start on an even 5 minute boundary and also have 5 minute intervals between X axis labels.  The out of the box behavior appears to not let us set a starting value for the X axis and an interval that matches a date/time boundary.   In other words, when showing more than a hour of real time collected data, we do not want to show the end user odd time icrement labels such as 12:37:32.

using System;
using System.Collections.ObjectModel;
using System.Windows;

namespace ScatterWithTextOnXAxis
{
    /// <summary>
    /// Interaction logic for MainWindow.xaml
    /// </summary>
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();

            DateTime start = new DateTime(2012, 04, 17, 12, 32, 31, 0);
            ObservableCollection<Data> graphData = new ObservableCollection<Data>();

            graphData.Add(new Data{ Y = 1, TimeValue = start });

            //we want the first X axis label to start on 12:30pm on Apr 17, 2012
            //we want the other X axis labels on the graph to be on even 5 minute boundaries
            //New data points would be added to the collectio about 1 each second (but not guaranteed on each and every second)

            int ctr = 1;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.63) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(1.13) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.23) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.56) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.90) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(1.42) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.03) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.24) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(1.55) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.34) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.78) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.90) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.21) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(2.63) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.04) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.37) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(1.60) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start}); start= start.AddMinutes(0.63) ;
            graphData.Add(new Data { Y = ctr++ * 5, TimeValue = start});

            DataContext = graphData;
        }
    }

    public class Data
    {
        public double X { get { return TimeValue.Ticks;  } }
        public double Y { get; set; }
        public DateTime TimeValue { get; set; }
    }
}