[英]typeError in Python when defining a input chanel of NI-DAQ
Python code for Data Aqusition using NI-DAQ. Python 代码用于使用 NI-DAQ 进行数据采集。 Had downloaded NI-driver
已经下载了NI驱动
Traceback (most recent call last):
File "C:\Users\icon\Desktop\DAQ 1.0.py", line 68, in <module>
chan = ctypes.create_string_buffer('Dev1/ai0')
File "C:\Python34\lib\ctypes\__init__.py", line 63, in
create_string_buffer
raise TypeError(init)
TypeError: Dev1/ai0
nidaq = ctypes.windll.nicaiu
int32 = ctypes.c_long
uInt32 = ctypes.c_ulong
uInt64 = ctypes.c_ulonglong
float64 = ctypes.c_double
TaskHandle = uInt32
written = int32()
pointsRead = uInt32()
DAQmx_Val_Volts = 10348
DAQmx_Val_Rising = 10280
DAQmx_Val_Cfg_Default = int32(-1)
DAQmx_Val_ContSamps = 10123
DAQmx_Val_ChanForAllLines = 1
DAQmx_Val_RSE = 10083
DAQmx_Val_Volts = 10348
DAQmx_Val_GroupByScanNumber = 1
DAQmx_Val_FiniteSamps = 10178
DAQmx_Val_GroupByChannel = 0
taskHandle = TaskHandle(0)
min1 = float64(-10.0)
max1 = float64(10.0)
timeout = float64(10.0)
bufferSize = uInt32(10)
pointsToRead = bufferSize
pointsRead = uInt32()
sampleRate = float64(200.0)
samplesPerChan = uInt64(100)
#specifiy the channels
chan = ctypes.create_string_buffer('Dev1/ai0')
clockSource = ctypes.create_string_buffer('OnboardClock')
According to [Python.Docs]: ctypes.create_string_buffer(init_or_size, size=None) ( emphasis is mine):根据[Python.Docs]: ctypes.create_string_buffer(init_or_size, size=None) (重点是我的):
init_or_size must be an integer which specifies the size of the array, or a bytes object which will be used to initialize the array items.
init_or_size必须是指定数组大小的integer ,或者是用于初始化数组项的字节 object 。
So, for your case, the simplest way to bypass this error would be to pass the bytes object to create_string_buffer .因此,对于您的情况,绕过此错误的最简单方法是将字节object 传递给create_string_buffer 。 Note that passing a string doesn't work in Python3 , because the " string " semantics have changed from Python2 (where it works).
请注意,传递字符串在Python3中不起作用,因为“字符串”语义已经从Python2 (它起作用的地方)发生了变化。
Example :示例:
>>> import sys, ctypes >>> print("Python {:s} on {:s}".format(sys.version, sys.platform)) Python 3.4.4 (v3.4.4:737efcadf5a6, Dec 20 2015, 20:20:57) [MSC v.1600 64 bit (AMD64)] on win32 >>> device_str = "Dev1/ai0" >>> >>> chan = ctypes.create_string_buffer(device_str) Traceback (most recent call last): File "<stdin>", line 1, in <module> File "c:\Install\x64\Python\Python\3.4\Lib\ctypes\__init__.py", line 63, in create_string_buffer raise TypeError(init) TypeError: Dev1/ai0 >>> >>> device_bytes = b"Dev1/ai0" # Use bytes literal directly >>> chan = ctypes.create_string_buffer(device_bytes) >>> chan, chan.value (<ctypes.c_char_Array_9 object at 0x00000000058E0DC8>, b'Dev1/ai0') >>> >>> chan = ctypes.create_string_buffer(device_str.encode()) # Use string's encode to convert it to bytes >>> chan, chan.value (<ctypes.c_char_Array_9 object at 0x00000000058E0E48>, b'Dev1/ai0')
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