如何在 Python 中将 PyHANDLE 对象传递给 CP2108 dll 函数（CP210xRuntime.dll）？

Question

我需要使用 Python 控制 CP2108 芯片 Latch。 C# 示例代码（来自制造商示例源）：

comString.Format(_T("\\\\.\\COM%d"), m_COMPort.GetCurSel() + 1);
//Open a handle the the device specified
HANDLE hDevice = CreateFile(comString,
                            GENERIC_READ | GENERIC_WRITE,
                            0,
                            0,
                            OPEN_EXISTING,
                            FILE_ATTRIBUTE_NORMAL | FILE_FLAG_OVERLAPPED,
                            0);

//If the handle is valid, then it opened
if (hDevice != INVALID_HANDLE_VALUE)
{
    WORD latch = 0;
    //Read the latch
    if (CP210xRT_ReadLatch(hDevice, &latch) != CP210x_SUCCESS)
    {.....}
 }

我的 Python 代码：

import win32file
import win32con
import ctypes

cp201x_dll = ctypes.windll.LoadLibrary('CP210xRuntime.dll')

lp_latch = ctypes.c_int(0)

h_device = win32file.CreateFile(r'\\.\\COM37',
                               win32con.GENERIC_READ|win32con.GENERIC_WRITE,
                               0,
                               None,
                               win32con.OPEN_EXISTING,
                               win32con.FILE_ATTRIBUTE_NORMAL|win32con.FILE_FLAG_OVERLAPPED,
                               None)



cp201x_dll.CP210xRT_ReadLatch(h_device, ctypes.byref(lp_latch))

print 'VALUE: {}'.format(lp_latch)

但我得到一个错误：

Traceback (most recent call last):
  File "D:/Dropbox/ElgsisTests/src/lib/cp210x/practise.py", line 27, in <module>
    cp201x_dll.CP210xRT_ReadLatch(h_device, ctypes.byref(lp_latch))
ctypes.ArgumentError: argument 1: <type 'exceptions.TypeError'>: Don't know how to convert parameter 1

我试图传递 ctypes 整数，但我得到的 Latch 值为零。我想这是因为这个 CP210xRuntime.dll 需要一个关于 COM 端口的信息。

来自 API 手册：

 3.1. CP210xRT_ReadLatch
    Description:

 Gets the current port latch value from the device.

    Supported Devices: CP2103, CP2104, CP2105, CP2108
    Location: CP210x Runtime DLL
    Prototype: CP210x_STATUS CP210xRT_ReadLatch(HANDLE Handle, LPWORD Latch)
    Parameters: 1. Handle—Handle to the Com port returned by CreateFile().
    2. Latch—Pointer for 4-byte return GPIO latch value [Logic High = 1, Logic Low = 0].
    Return Value: CP210x_STATUS = CP210x_SUCCESS,
    CP210x_INVALID_HANDLE,
    CP210x_DEVICE_IO_FAILED
    CP210x_FUNCTION_NOT_SUPPORTED

所以也许有人知道如何正确传递它？

Answer 1

更新了 Python 代码：

handle = ctypes.c_long(int(h_device))
status = cp201x_dll.CP210xRT_ReadLatch(handle, ctypes.byref(lp_latch))
print 'STATUS: {}'.format(status)
print 'VALUE: {}'.format(lp_latch)

并且确实收到了正确的值