如图所示，实时从云端接受排队人数数据，并在折线图中实时更新，首先新建一个定时器：

private ObservableDataSource<Point> dataSource3 = new ObservableDataSource<Point>();//排队人数

设置刷新时间，chart2为要更新的折线图：

public Window1()
{
    
    
   InitializeComponent();
  
   timer2.Tick += new EventHandler(timer_Tick2);
   timer2.Interval = TimeSpan.FromSeconds(5);   //设置刷新的间隔时间5s

   chart2.AddLineGraph(dataSource3, Colors.Green, 2, "排队人数");//
   chart2.Viewport.Visible = new Rect(0, 0, 20, 40);
}

定时器内容：

void timer_Tick2(object sender, EventArgs e)//更新人数
{
    
    
    var SDK = new NLECloudAPI("http://api.nlecloud.com");
    dynamic qry1 = SDK.GetSensorInfo(deviceId, "people", Token);
    if (qry1.IsSuccess())
    {
    
    
        Console.WriteLine("success!!!!");
    }
    string json = SerializeToJson(qry1);
    JObject result = JObject.Parse(json);
    string value1 = result["ResultObj"]["Value"].ToString();
    CHART(Convert.ToDouble(value1));
    this.textbox_number.Dispatcher.Invoke(new outputDelegate(outputAction), value1);//显示人数
    data.Dispatcher.Invoke(new outputDelegate(outputAction2), value1);
}

public void outputAction(string msg)
{
    
    
    textbox_number.Text = msg + "人";
}
public void CHART(double xx)//打印折线图
{
    
    
    double x = temp1_num;//定义全局变量temp1_num=0，表示x值;
    Point point = new Point(x, xx);
    dataSource3.AppendAsync(base.Dispatcher, point);
    chart2.Viewport.FitToView();
    temp1_num += 5;//坐标加5（5秒1跳）
    int newX = 0;
    double newY = 2 * xx;
    //实现折现图自动滚动,x轴最多显示20个数据，num_num表示x最小值
    if (num_num > 20)
    {
    
    
        newX = num_num - 20;
    }
    chart2.Viewport.Visible = new Rect(newX, 0, 20, newY);
    num_num+=5;
}
private string SerializeToJson(object qry)
{
    
    
    return Newtonsoft.Json.JsonConvert.SerializeObject(qry);
}

开始获取数据按钮和暂停按钮：

private void Button_Click_4(object sender, RoutedEventArgs e)//暂停取号
{
    
    
    var SDK = new NLECloudAPI("http://api.nlecloud.com");
    String actuatorApiTag = "key";    //发送命令的执行器标识名
    dynamic qry;
    qry = SDK.Cmds(deviceId, actuatorApiTag, 0, Token);
    timer2.Stop();
}
private void Button_Click_3(object sender, RoutedEventArgs e)//开始取号
{
    
    
    var SDK = new NLECloudAPI("http://api.nlecloud.com");
    String actuatorApiTag = "key";    //发送命令的执行器标识名
    dynamic qry;
    qry = SDK.Cmds(deviceId, actuatorApiTag, 1, Token);
    timer2.Start();
}

至此，一个从云端接受数据的并实时更新的折线图便完成了！！！