c#怎么判断设备是否离线，就是用的新大陆云平台，云平台会超时离线，怎么判断是否离线

问题遇到的现象和发生背景

    public MainWindow ()
    {
        InitializeComponent ();
    }

    private void btn_login_Loaded (object sender, RoutedEventArgs e)
    {
        
        AccountLoginDTO dto = new AccountLoginDTO ();//用户登录DTO
        dto.Account = userName.Text.Trim ();// txtName.Text.Trim();
        dto.Password = password.Text.Trim ();// pasPwd.Password;


        if (this.userName.Text.Trim () != "")
        {
            if (this.password.Text.Trim () != "")
            {
                ResultMsg<AccountLoginResultDTO> qry = sdk.UserLogin (dto);
                if (qry.IsSuccess ())
                {
                    mToken = qry.ResultObj.AccessToken;
                    if (String.IsNullOrEmpty (mToken))
                    {
                        qry.SetFailure ("Token 为空");
                    }
                    MessageBox.Show (mToken);//显示获取的AccessToken
                    
                }
                else
                {
                    MessageBox.Show ("登录失败", "提示");

                }
            }
            else
            {
                MessageBox.Show ("密码为空，请输入密码！");
            }
        }
        else
        {
            MessageBox.Show ("账号为空，请输入账号！");
        }
    }

    private void button_Click (object sender, RoutedEventArgs e)
    {
        ResultMsg<SensorBaseInfoDTO>  get=sdk.GetSensorInfo (440524, "z_temperature", mToken);
        sdk.Cmds (440524, "rqvhazigeren",1,mToken);
        textBox.Text = get.ResultObj.Value.ToString ()          
    }

    private void textBox_TextChanged (object sender, TextChangedEventArgs e)
    {       
    }
}

}

运行结果及报错内容

我的解答思路和尝试过的方法

我想要达到的结果可能 可以通过执行器或者传感器来判断设备是否离线吗

增加一个心跳包试一试