沒有發票機，透過網路型出單機開錢櫃的解決方法

　　這段實在很重要，對於VB6的程式來說，要開錢櫃，在有接發票機的情形下，直接輸出LPT即可，，沒有發票機時只能透過熱感式出單機協助。但現在有些熱感式出單機是網路型的，直接輸出LPT就沒用了。

　　所以，當你的電腦接網路，網路接出單機，而出單機再接錢櫃時，下列的範例就是很好用的C#程式，以我的狀況是，用C#寫一支下列程式，呼叫下面這個Class，打開錢櫃後就自動結束程式；接著在VB6呼叫這隻程式，就可以很開心的在沒有發票機的狀況下打開錢櫃啦~

PS:很抱歉，這段資料的來源我忘了保留下來了，如果有人知道，也可以告訴我，我會立即補上出處的，感謝~

using System;
using System.Drawing;
using System.Drawing.Printing;
using System.IO;
using System.Windows.Forms;
using System.Runtime.InteropServices;

class RawPrinterHelper
    {
        // Structure and API declarions:
        [StructLayout(LayoutKind.Sequential, CharSet = CharSet.Ansi)]
        public class DOCINFOA
        {
            [MarshalAs(UnmanagedType.LPStr)]
            public string pDocName;
            [MarshalAs(UnmanagedType.LPStr)]
            public string pOutputFile;
            [MarshalAs(UnmanagedType.LPStr)]
            public string pDataType;
        }
        [DllImport("winspool.Drv", EntryPoint = "OpenPrinterA", SetLastError = true, CharSet = CharSet.Ansi, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool OpenPrinter([MarshalAs(UnmanagedType.LPStr)] string szPrinter, out IntPtr hPrinter, IntPtr pd);

        [DllImport("winspool.Drv", EntryPoint = "ClosePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool ClosePrinter(IntPtr hPrinter);

        [DllImport("winspool.Drv", EntryPoint = "StartDocPrinterA", SetLastError = true, CharSet = CharSet.Ansi, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool StartDocPrinter(IntPtr hPrinter, Int32 level, [In, MarshalAs(UnmanagedType.LPStruct)] DOCINFOA di);

        [DllImport("winspool.Drv", EntryPoint = "EndDocPrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool EndDocPrinter(IntPtr hPrinter);

        [DllImport("winspool.Drv", EntryPoint = "StartPagePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool StartPagePrinter(IntPtr hPrinter);

        [DllImport("winspool.Drv", EntryPoint = "EndPagePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool EndPagePrinter(IntPtr hPrinter);

        [DllImport("winspool.Drv", EntryPoint = "WritePrinter", SetLastError = true, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
        public static extern bool WritePrinter(IntPtr hPrinter, IntPtr pBytes, Int32 dwCount, out Int32 dwWritten);

        // SendBytesToPrinter()
        // When the function is given a printer name and an unmanaged array
        // of bytes, the function sends those bytes to the print queue.
        // Returns true on success, false on failure.
        public static bool SendBytesToPrinter(string szPrinterName, IntPtr pBytes, Int32 dwCount)
        {
            Int32 dwError = 0, dwWritten = 0;
            IntPtr hPrinter = new IntPtr(0);
            DOCINFOA di = new DOCINFOA();
            bool bSuccess = false; // Assume failure unless you specifically succeed.

            di.pDocName = "My C#.NET RAW Document";
            di.pDataType = "RAW";

            // Open the printer.
            if (OpenPrinter(szPrinterName.Normalize(), out hPrinter, IntPtr.Zero))
            {
                // Start a document.
                if (StartDocPrinter(hPrinter, 1, di))
                {
                    // Start a page.
                    if (StartPagePrinter(hPrinter))
                    {
                        // Write your bytes.
                        bSuccess = WritePrinter(hPrinter, pBytes, dwCount, out dwWritten);
                        EndPagePrinter(hPrinter);
                    }
                    EndDocPrinter(hPrinter);
                }
                ClosePrinter(hPrinter);
            }
            // If you did not succeed, GetLastError may give more information
            // about why not.
            if (bSuccess == false)
            {
                dwError = Marshal.GetLastWin32Error();
            }
            return bSuccess;
        }

    }

Then use the following method to open the cash drawer

private void openCashDrawer()

        {

            //下面這行請改成錢櫃的指令
            byte[] codeOpenCashDrawer = new byte[] { 27, 112, 48, 55, 121 };

            IntPtr pUnmanagedBytes = new IntPtr(0);

            pUnmanagedBytes = Marshal.AllocCoTaskMem(5);

            Marshal.Copy(codeOpenCashDrawer, 0, pUnmanagedBytes, 5);

            //下面這行的第一個參數"EPSON xxxx" 請改成印表機名稱，名稱哦~~很方便的
            RawPrinterHelper.SendBytesToPrinter("EPSON TM-T88V Receipt Invoice", pUnmanagedBytes, 5);

            Marshal.FreeCoTaskMem(pUnmanagedBytes);

        }