C#

_dtPreviousService1Time datetime;
_dtPreviousService2Time datetime;
...
...

foreach(ServerMonitor item in monitorSettings)
{
    if (item.Servicename == "service1") //check for service1...
    {
       if (_dtPreviousService1Time != DateTime.MinValue)
       {
        TimeSpan span = PresentTime.Subtract(_dtPreviousService1Time);
        dblTimeDifference = span.TotalSeconds;
        _dtPreviousService1Time = PresentTime;//store as last (Previous) received time...
       }
       else
       {
       _dtPreviousService1Time = DateTime.Now;//first time round capturing messages...
       }
       
       break; //come out of the foreach loop...
    }
    elseif (item.Servicename == "service2") //check for the service2...
    {
     ...
     ...
     ...
    }

}

...
...
...

static public class Img
{
        static public Bitmap Crop(Bitmap image, Rectangle rect)
        {
                Bitmap cropped = new Bitmap(rect.Width, rect.Height, image.PixelFormat);
                using (Graphics g = Graphics.FromImage(cropped))
                {
                        g.DrawImageUnscaledAndClipped(image, rect);
                        return cropped;
                }
        }
}