Python for .NET：如何提供特殊类型的变量 (FTDI.FT_DEVICE_INFO_NODE[]) 作为方法参数

Question

我想在 Python 的帮助下使用 DLL for .NET (pythonnet)。此 DLL 中的方法需要（指向？）变量作为参数。

我可以弄清楚如何调用方法并提供整数变量作为参数。

如果需要特殊类型（此处：FTD2XX_NET.FTDI.FT_DEVICE_INFO_NODE[]），我不知道如何提供这样的参数变量。

当尝试调用 FTDI.GetDeviceList 的不同变体时（其中一些在技术上是相同的），我遇到了不同类型的错误：

TypeError: 没有方法匹配给定的参数

FTDI.GetDeviceList([ftdi.FT_DEVICE_INFO_NODE()][:])
FTDI.GetDeviceList(ftdi.FT_DEVICE_INFO_NODE)
FTDI.GetDeviceList(ftdi.FT_DEVICE_INFO_NODE())
FTDI.GetDeviceList(ftdi.FT_DEVICE_INFO_NODE(device_count))
FTDI.GetDeviceList([devicelist_])
FTDI.GetDeviceList(devicelist_)

类型错误：无法索引的对象

FTDI.GetDeviceList(ftdi.FT_DEVICE_INFO_NODE()[:])

类型错误：预期类型

FTDI.GetDeviceList(ftdi.FT_DEVICE_INFO_NODE[:])
FTDI.GetDeviceList(ftdi.FT_DEVICE_INFO_NODE[1])
FTDI.GetDeviceList(ftdi.FT_DEVICE_INFO_NODE[0])

这里是代码摘要，结果：

import clr
import sys
sys.path.append("C:\Users\[...]\FTD2XX_NET_v1.1.0\") # path to dll
clr.AddReference("System")
clr.AddReference("FTD2XX_NET")
from FTD2XX_NET import FTDI
from System import UInt32
ftdi = FTDI()

if __name__ == '__main__':

# This method requires an integer as parameter, the code is working
    # M:FTD2XX_NET.FTDI.GetLibraryVersion(System.UInt32@)
    # summary: Gets the current FTD2XX.DLL driver version number.
    # returns: FT_STATUS value from FT_GetLibraryVersion in FTD2XX.DLL
    # param: name: LibraryVersion. The current library version.

    version_ = 0 # empty variable to provide as parameter
    ft_status, version = ftdi.GetLibraryVersion(version_)
    print('status: {}\nversion: {}'.format(ft_status, version)) 
    # prints 
    # status: 0
    # version: 197140

# This method requires an FT_DEVICE_INFO_NODE[] as parameter, the code is not working
    # M:FTD2XX_NET.FTDI.GetDeviceList(FTD2XX_NET.FTDI.FT_DEVICE_INFO_NODE[])
    # summary: Gets information on all of the FTDI devices available.
    # returns: FT_STATUS value from FT_GetDeviceInfoDetail in FTD2XX.DLL
    # param: name: devicelist. 
    #        An array of type FT_DEVICE_INFO_NODE to contain the device information 
    #        for all available devices.

    # no idea how to create the fitting parameter FT_DEVICE_INFO_NODE[]
    devicelist_ = ftdi.FT_DEVICE_INFO_NODE() # empty variable to provide as parameter
    print(devicelist_.Flags, devicelist_.Type, devicelist_.ID, 
          devicelist_.LocId, devicelist_.SerialNumber, 
          devicelist_.Description, devicelist_.ftHandle) 
    # prints
    # 0 0 0 0 None None 0

    status, devicelist = FTDI.GetDeviceList(devicelist_)
    print(devicelist)
    # throws a TypeError: No method matches given arguments

Here 我发现了一些 c# 代码，其中 FT_DEVICE_INFO_NODE[] 和 GetDeviceList 在方法中使用：

private int countDevices()
{
    FTDI.FT_STATUS ftStatus = FTDI.FT_STATUS.FT_OK;
    ftStatus = myDevice.GetNumberOfDevices(ref ftdiDeviceCount);
    if (ftStatus != FTDI.FT_STATUS.FT_OK)
        return 0;
    if (ftdiDeviceCount > 0)
    {
        //allocate device info list
        ftdiDeviceList = new FTDI.FT_DEVICE_INFO_NODE[ftdiDeviceCount];
        //populate list
        ftStatus = myDevice.GetDeviceList(ftdiDeviceList);
        if (ftStatus == FTDI.FT_STATUS.FT_OK)
        {
            return (int)ftdiDeviceCount;
        }
        else
            return 0;
    }
    else
        return 0;
}

将 FTDI.FT_DEVICE_INFO_NODE[] 作为参数提供给 FTDI.GetDeviceList 我错过了什么？

FTDI 的 USB 驱动程序在这里下载：http://www.ftdichip.com/Drivers/D2XX.htm, and the .Net wrapper was downloaded from here: http://www.ftdichip.com/Support/SoftwareExamples/CodeExamples/CSharp.htm

Answer 1

源代码需要一个包含 FT_DEVICE_INFO_NODE 的列表。这是函数声明：

public FTDI.FT_STATUS GetDeviceList(FTDI.FT_DEVICE_INFO_NODE[] devicelist)

这段代码对我有用：

ft_device_info_node = ftdi.FT_DEVICE_INFO_NODE()
ft_status = ftdi.GetDeviceList([ft_device_info_node])
print(ft_status)

最后我放弃了这个功能，因为我无法达到我想要的return，而是使用了"GetDeviceID"、"GetDescription"和"GetSerialNumber" 打开我想从中获取信息的设备后单独运行。

示例：

# Open
ftdi.OpenByIndex(0)
print("Opened Index 0")

# Get Device ID
device_id = 0
ft_status, device_id = ftdi.GetDeviceID(device_id)
assert(ft_status == 0)
print(device_id)

# Close
ftdi.Close()
print("Closed")

Answer 2

我知道这个 post 已经过时了，但它仍然适用。对我有用的技巧是创建类型为 FTD2XX_NET.FT_DEVICE_INFO_NODE[] 的数组实例，长度设置为 FTDI 设备数：

    # -*- coding: utf-8 -*-
    """
    Created on Wed May 13 15:50:22 2020

    @author: chogh
    """
    # For Windows, from a Anaconda Prompt cmd window:
    # conda install -c ipython pythonnet  # so import System classes are exposed
    # conda install -c ipython ftd2xx     # so import FTD2XX_NET classes are exposed
    #
    #############################################################################

    import System                     # available after running conda install -c                 ipython pythonnet in Anaconda Prompt cmd window
    import clr
    from System import Array          # to import .Net Array functions for FTD2XX_NET
    from System import Byte           # to import .Net Array functions for FTD2XX_NET
    from array import array
    clr.AddReference("System")
    clr.AddReference('FTD2XX_NET')
    from FTD2XX_NET import FTDI

    myFtdiDevice=FTDI()

    ft_status = myFtdiDevice.FT_STATUS.FT_DEVICE_NOT_FOUND

    DeviceNum=0
    ft_status,DeviceNum=myFtdiDevice.GetNumberOfDevices(DeviceNum)
    DeviceList=Array.CreateInstance(myFtdiDevice.FT_DEVICE_INFO_NODE, DeviceNum)
    ft_status=myFtdiDevice.GetDeviceList(DeviceList)
    print("ft_status:", ft_status)
    print("Device Description: ",DeviceList[0].Description)
    print("Device Serial Number: ",DeviceList[0].SerialNumber)
    print("Device Device ID: ",DeviceList[0].ID)
    print("Device Device Type: ",DeviceList[0].Type)

这导致以下输出：

Reloaded modules: System, FTD2XX_NET

ft_status: 0
Device Description:  Hazelnut
Device Serial Number:  FTWLN0XM
Device Device ID:  67330068
Device Device Type:  8

Python for .NET：如何提供特殊类型的变量 (FTDI.FT_DEVICE_INFO_NODE[]) 作为方法参数

Python for .NET: How to provide a variable of special type (FTDI.FT_DEVICE_INFO_NODE[]) as method parameter

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