//获取系统中的串口并加入到下拉框中            cbCashBoxPort.Items.Clear();            string[] ports = System.IO.Ports.SerialPort.GetPortNames();            if (ports != null)            {                foreach (string port in ports)                {                    cbCashBoxPort.AddItem(port, port);                }            }            //获取系统中的并口并加入到下拉框中            using (ManagementObjectSearcher seacher = new ManagementObjectSearcher("select * from Win32_ParallelPort"))            {                foreach (ManagementObject item in seacher.Get())                {                        PropertyData data = item.Properties["Caption"];                        cbCashBoxPort.AddItem(data.Value.ToString(),data.Value.ToString());                }            }