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我需要开发一个应用程序来打印到热敏打印机，例如 Epson ESC/POS 协议或 ZPL Zebra 协议。我可以使用网络打印机、串行端口打印机以及窗口的假脱机打印机将原始代码写入打印机。当我需要“查询”打印机以获取其状态（就绪、错误、纸张用完等）时，我的麻烦就开始了，在这种情况下，我需要反向通信，我发送一个特殊命令，打印机用一些状态字节回答. 使用网络/套接字打印机或串行端口打印机，一切都很清楚......使用 Windows 打印机我无法理解如何读取打印机状态......

有什么解决办法吗？

更新

按照汉斯的建议，我正在尝试使用 Windows API 读取打印机。这是我对 ESC/POS 协议的测试。

public class WinPrinter
{
    // 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);

    [DllImport("winspool.Drv", EntryPoint = "ReadPrinter", SetLastError = true, CharSet = CharSet.Unicode, ExactSpelling = true, CallingConvention = CallingConvention.StdCall)]
    public static extern bool ReadPrinter(IntPtr hPrinter, [MarshalAs(UnmanagedType.LPStr)] StringBuilder pBytes, Int32 dwCount, out Int32 dwNReadBytes); 

    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);
            }
            string reaDstrinG = "";
            Int32 buf = 0;
            Int32 pcRead;
            System.Text.StringBuilder sb = new System.Text.StringBuilder();
            bool read = ReadPrinter(hPrinter, sb.Append(reaDstrinG), buf, out pcRead);
            ClosePrinter(hPrinter);
        }
        // If you did not succeed, GetLastError may give more information
        // about why not.
        if (bSuccess == false)
        {
            dwError = Marshal.GetLastWin32Error();
        }
        return bSuccess;


      }

       static void Main(string[] args)
        {
            String test = "\u0010\u0004\u0001";
            IntPtr pBytes=Marshal.StringToCoTaskMemAnsi(test);
            Int32 dwCount = test.Length;
            WinPrinter.SendBytesToPrinter("BIXOLON SRP-350 (Copia 1)",pBytes,dwCount);
        }

    }

我确定“\u0010\u0004\u0001”（DLE EOT 1）是在 ESCPOS 协议中请求打印机状态的推荐，我用串行连接的同一台打印机对其进行了测试，我得到了一个状态字节。

但是，对于上面的代码，我总是从 ReadPrinter 方法中得到错误。我检查了打印机端口是否启用了“双向”选项，并且我也尝试过不使用后台处理程序选项。

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