我是Python新手。我试图通过其DLL库连接到激光传感器。本库中的SDK函数是用C ++语言编译的。
通过在python中使用ctypes,我的第一个尝试是调用EthernetScanner_Connect函数。功能参数如下:
void* EthernetScanner_Connect(char *chIP, char *chPort, int iTimeOut)
根据c ++中的函数描述,如果发生连接失败,它应返回NULL指针,否则它应该返回配置文件传感器的句柄,该传感器将用于其他函数。
我在python上的代码到现在为止:
from ctypes import *
lib=windll.LoadLibrary("c:\\EthernetScanner.dll")
if lib:
print("the Library is loaded")
EthernetScanner_Connect = getattr(lib,"EthernetScanner_Connect")
EthernetScanner_Connect.restype = c_void_p
EthernetScanner_Connect.argtypes =[c_char_p,c_char_p,c_int]
x = EthernetScanner_Connect(b"193.164.200.1\0",b"32407\0",0)
print(x)
虽然我期待此函数为NULL,因为我还没有连接到传感器,它给了我以下内容:
the Library is loaded
45940800
我想首先指出[Python 3.Docs]: ctypes - A foreign function library for Python。
我将基于一些假设发布答案:
这是一段应该解决问题的代码(不用说它是盲目编码 - 这意味着我实际上没有对它进行测试)。 作为第二个假设的结果,如果超时大于0,则EthernetScanner_Connect应返回NULL。
code.朋友:
#!/usr/bin/env python3
import sys
import ctypes
import time
DLL_NAME = "c:\\EthernetScanner.dll"
CONNECT_STATUS_DISCONNECTED = 0
CONNECT_STATUS_DISCONNECTING = 1
CONNECT_STATUS_CONNECTING = 2
CONNECT_STATUS_CONNECTED = 3
CONNECT_STATUSES_PENDING = [
CONNECT_STATUS_CONNECTING,
CONNECT_STATUS_DISCONNECTING,
]
def main():
connect_timeout_msec = 0
nb_mode = connect_timeout_msec == 0
dll = ctypes.WinDLL(DLL_NAME)
EthernetScanner_Connect = dll.EthernetScanner_Connect
EthernetScanner_Connect.argtypes = [ctypes.c_char_p, ctypes.c_char_p, ctypes.c_uint32]
EthernetScanner_Connect.restype = ctypes.c_void_p
EthernetScanner_GetConnectStatus = dll.EthernetScanner_GetConnectStatus
EthernetScanner_GetConnectStatus.argtypes = [ctypes.c_void_p, ctypes.POINTER(ctypes.c_uint32)]
EthernetScanner_Disconnect = dll.EthernetScanner_Disconnect
EthernetScanner_Disconnect.argtypes = [ctypes.c_void_p]
EthernetScanner_Disconnect.restype = ctypes.c_uint32
ptr = EthernetScanner_Connect(b"192.168.100.1", b"32001", connect_timeout_msec)
if nb_mode:
print("Non blocking mode: EthernetScanner_Connect returned {:}".format(ptr))
poll_timeout_sec = 0.5
connect_status = ctypes.c_int(CONNECT_STATUS_CONNECTING)
while connect_status.value in CONNECT_STATUSES_PENDING:
time.sleep(poll_timeout_sec)
EthernetScanner_GetConnectStatus(ptr, ctypes.byref(connect_status))
if connect_status.value != CONNECT_STATUS_CONNECTED:
print("Couldn't connect (status: {:})!".format(connect_status.value))
return
else:
print("Blocking mode: EthernetScanner_Connect returned {:}".format(ptr))
if not ptr:
print("Couldn't connect!")
return
# Do something with the sensor (pointer)
EthernetScanner_Disconnect(ptr)
if __name__ == "__main__":
print("Python {:s} on {:s}\n".format(sys.version, sys.platform))
main()
print("Done.")