在网上找了一堆的方法 基本都是C++或者VB 的DLL调用之类的
    其实还有另一种2005的SerialPort方法 
下载源代码
   ---------------------------控制台程序----------------------

using System;
using System.Collections.Generic;
using System.Text;
using System.IO.Ports;

namespace EAD.POS
{
    class SerialPortOutput
    {
        /// <summary>
        /// 总计
        /// </summary>
        /// <param name="value">The value.</param>
        public static void Sum(string value)
        {
            Clear();
            //收款();
            //找零();
            newData(value);
            总计();
        }
        /// <summary>
        /// 单价
        /// </summary>
        /// <param name="value">The value.</param>
        public static void UnitPrice(string value)
        {
            Clear();
            newData(value);
            单价();
        }
        /// <summary>
        /// 收款
        /// </summary>
        /// <param name="value">The value.</param>
        public static void Get(string value)
        {
            Clear();
            newData(value);
            收款();
        }
        /// <summary>
        /// 找零
        /// </summary>
        /// <param name="value">The value.</param>
        public static void change(string value)
        {
            Clear();
            newData(value);
            找零();
        }
        /// <summary>
        ///全暗.是找零 全价 收款 这几个灯
        /// </summary>
        public static void AllBlack()
        {
            SerialPort serialPort1 = new SerialPort();
            serialPort1.PortName = "COM1";
            serialPort1.BaudRate = 2400;
            serialPort1.Open();
            serialPort1.WriteLine(@"s0");
            serialPort1.Close();
        }
        /// <summary>
        /// 清屏.
        /// </summary>
        public static void Clear()
        {
            SerialPort serialPort1 = new SerialPort();
            serialPort1.PortName = "COM1";
            serialPort1.BaudRate = 2400;
            serialPort1.Open();
            serialPort1.WriteLine("\f");
            serialPort1.Close();
        }
        private static void 单价()
        {
            SerialPort serialPort1 = new SerialPort();
            serialPort1.PortName = "COM1";
            serialPort1.BaudRate = 2400;
            serialPort1.Open();
            serialPort1.WriteLine("s1");//其实有数据的那个空格
            serialPort1.Close();
        }
        private static void 总计()
        {
            SerialPort serialPort1 = new SerialPort();
            serialPort1.PortName = "COM1";
            serialPort1.BaudRate = 2400;
            serialPort1.Open();
            serialPort1.WriteLine(@"s2");
            serialPort1.Close();
        }
        private static void 收款()
        {
            SerialPort serialPort1 = new SerialPort();
            serialPort1.PortName = "COM1";
            serialPort1.BaudRate = 2400;
            serialPort1.Open();
            serialPort1.WriteLine(@"s3");
            serialPort1.Close();
        }
        private static void 找零()
        {
            SerialPort serialPort1 = new SerialPort();
            serialPort1.PortName = "COM1";
            serialPort1.BaudRate = 2400;
            serialPort1.Open();
            serialPort1.WriteLine(@"s4");
            serialPort1.Close();
        }
        private static void newData(string data)
        {
            SerialPort serialPort1 = new SerialPort();
            serialPort1.PortName = "COM1";
            serialPort1.BaudRate = 2400;
            serialPort1.Open();
            serialPort1.WriteLine(@"QA" + data);
            serialPort1.Close();
        }

}
}
    ---------------------------控制台程序----------------------

using System;
using System.Collections.Generic;
using System.Text;
using EAD.POS;
namespace ConsoleApplication2
{
    class Program
    {
        static void Main(string[] args)
        {
            for (; ; )
            {
                SerialPortOutput.Clear();
                System.Threading.Thread.Sleep(2000);
                SerialPortOutput.change("21230.34");
                System.Threading.Thread.Sleep(2000);
                SerialPortOutput.Get("230.34");
                System.Threading.Thread.Sleep(2000);
                SerialPortOutput.Sum("99230.34");
                System.Threading.Thread.Sleep(2000);
                SerialPortOutput.UnitPrice("30.34");
                System.Threading.Thread.Sleep(2000);
            }

}
    }
}

顺便问一下这样的STATIC方法怎么个重构法