使用python来调用CAN通讯的DLL实现方法

时间：2020-12-07 16:36:03|栏目：Python代码|点击：次

由于工作上的需要，经常要与USBCAN打交道，但厂家一般不会提供PYTHON的例子，于是自己摸索地写一个例子出来，以便在工作上随时可以使用PYTHON来测试CAN的功能。这里的例子是使用珠海创芯科技有限公司的USBCAN接口卡，他们提供一个ControlCAN.dll，也提供了一个.h文件，如下：

#ifndef CONTROLCAN_H
#define CONTROLCAN_H
 
////文件版本：v2.00 20150920
//#include <cvidef.h>	//使用CVI平台开发，请使用该语句。
 
//接口卡类型定义
 
#define VCI_USBCAN1		3
#define VCI_USBCAN2		4
#define VCI_USBCAN2A		4
 
#define VCI_USBCAN_E_U 		20
#define VCI_USBCAN_2E_U 	21
 
 
 
//函数调用返回状态值
#define	STATUS_OK					1
#define STATUS_ERR					0
	
/*------------------------------------------------兼容ZLG的函数及数据类型------------------------------------------------*/
//1.ZLGCAN系列接口卡信息的数据类型。
typedef struct _VCI_BOARD_INFO{
		unsigned short	hw_Version;
		unsigned short	fw_Version;
		unsigned short	dr_Version;
		unsigned short	in_Version;
		unsigned short	irq_Num;
		unsigned char	can_Num;
		char	str_Serial_Num[20];
		char	str_hw_Type[40];
		unsigned short	Reserved[4];
} VCI_BOARD_INFO,*PVCI_BOARD_INFO; 
 
//2.定义CAN信息帧的数据类型。
typedef struct _VCI_CAN_OBJ{
	unsigned int	ID;
	unsigned int	TimeStamp;
	unsigned char	TimeFlag;
	unsigned char	SendType;
	unsigned char	RemoteFlag;//是否是远程帧
	unsigned char	ExternFlag;//是否是扩展帧
	unsigned char	DataLen;
	unsigned char	Data[8];
	unsigned char	Reserved[3];
}VCI_CAN_OBJ,*PVCI_CAN_OBJ;
 
//3.定义初始化CAN的数据类型
typedef struct _VCI_INIT_CONFIG{
	unsigned long	AccCode;
	unsigned long	AccMask;
	unsigned long	Reserved;
	unsigned char	Filter;
	unsigned char	Timing0;	
	unsigned char	Timing1;	
	unsigned char	Mode;
}VCI_INIT_CONFIG,*PVCI_INIT_CONFIG;
 
///////// new add struct for filter /////////
typedef struct _VCI_FILTER_RECORD{
	unsigned long	ExtFrame;	//是否为扩展帧
	unsigned long	Start;
	unsigned long	End;
}VCI_FILTER_RECORD,*PVCI_FILTER_RECORD;
 
#define EXTERNC		extern "C"
 
EXTERNC unsigned long __stdcall VCI_OpenDevice(unsigned long DeviceType,unsigned long DeviceInd,unsigned long Reserved);
EXTERNC unsigned long __stdcall VCI_CloseDevice(unsigned long DeviceType,unsigned long DeviceInd);
EXTERNC unsigned long __stdcall VCI_InitCAN(unsigned long DeviceType, unsigned long DeviceInd, unsigned long CANInd, PVCI_INIT_CONFIG pInitConfig);
 
EXTERNC unsigned long __stdcall VCI_ReadBoardInfo(unsigned long DeviceType,unsigned long DeviceInd,PVCI_BOARD_INFO pInfo);
 
EXTERNC unsigned long __stdcall VCI_SetReference(unsigned long DeviceType,unsigned long DeviceInd,unsigned long CANInd,unsigned long RefType,void* pData);
 
EXTERNC unsigned long __stdcall VCI_GetReceiveNum(unsigned long DeviceType,unsigned long DeviceInd,unsigned long CANInd);
EXTERNC unsigned long __stdcall VCI_ClearBuffer(unsigned long DeviceType,unsigned long DeviceInd,unsigned long CANInd);
 
EXTERNC unsigned long __stdcall VCI_StartCAN(unsigned long DeviceType,unsigned long DeviceInd,unsigned long CANInd);
EXTERNC unsigned long __stdcall VCI_ResetCAN(unsigned long DeviceType,unsigned long DeviceInd,unsigned long CANInd);
 
EXTERNC unsigned long __stdcall VCI_Transmit(unsigned long DeviceType,unsigned long DeviceInd,unsigned long CANInd,PVCI_CAN_OBJ pSend,unsigned long Len);
EXTERNC unsigned long __stdcall VCI_Receive(unsigned long DeviceType,unsigned long DeviceInd,unsigned long CANInd,PVCI_CAN_OBJ pReceive,unsigned long Len,int WaitTime);
 
 
/*------------------------------------------------其他补充函数及数据结构描述------------------------------------------------*/
 
//USB-CAN总线适配器板卡信息的数据类型1，该类型为VCI_FindUsbDevice函数的返回参数。
typedef struct _VCI_BOARD_INFO1{
	unsigned long	hw_Version;
	unsigned long	fw_Version;
	unsigned long	dr_Version;
	unsigned long	in_Version;
	unsigned long	irq_Num;
	unsigned char	can_Num;
	unsigned char	Reserved;
	char	str_Serial_Num[8];
	char	str_hw_Type[16];
	char	str_Usb_Serial[4][4];
} VCI_BOARD_INFO1,*PVCI_BOARD_INFO1;
 
//USB-CAN总线适配器板卡信息的数据类型2，该类型为VCI_FindUsbDevice函数的返回参数。为扩展更多的设备
typedef struct _VCI_BOARD_INFO2{
	unsigned long	hw_Version;
	unsigned long	fw_Version;
	unsigned long	dr_Version;
	unsigned long	in_Version;
	unsigned long	irq_Num;
	unsigned char	can_Num;
	unsigned char	Reserved;
	char	str_Serial_Num[8];
	char	str_hw_Type[16];
	char	str_Usb_Serial[10][4];
} VCI_BOARD_INFO2,*PVCI_BOARD_INFO2;
 
 
#define EXTERNC		extern "C"
 
EXTERNC unsigned long __stdcall VCI_GetReference2(unsigned long DevType,unsigned long DevIndex,unsigned long CANIndex,unsigned long Reserved,unsigned char *pData);
EXTERNC unsigned long __stdcall VCI_SetReference2(unsigned long DevType,unsigned long DevIndex,unsigned long CANIndex,unsigned long RefType,unsigned char *pData);
 
 
EXTERNC unsigned long __stdcall VCI_ConnectDevice(unsigned long DevType,unsigned long DevIndex);
EXTERNC unsigned long __stdcall VCI_UsbDeviceReset(unsigned long DevType,unsigned long DevIndex,unsigned long Reserved);
EXTERNC unsigned long __stdcall VCI_FindUsbDevice(PVCI_BOARD_INFO1 pInfo);
EXTERNC unsigned long __stdcall VCI_FindUsbDevice2(PVCI_BOARD_INFO2 pInfo);
 
 
 
#endif

要调用这些函数才可以完成工作，下面就来创建一个例子，从CAN的通道0向通道1来发送一帧CAN数据，例子代码如下：

#python3.6 32位
#https://blog.csdn.net/caimouse/article/details/51749579
#开发人员：蔡军生（QQ：9073204） 深圳 2018-3-25
#
from ctypes import *
 
VCI_USBCAN2A = 4
STATUS_OK = 1
class VCI_INIT_CONFIG(Structure): 
  _fields_ = [("AccCode", c_ulong),
        ("AccMask", c_ulong),
        ("Reserved", c_ulong),
        ("Filter", c_ubyte),
        ("Timing0", c_ubyte),
        ("Timing1", c_ubyte),
        ("Mode", c_ubyte)
        ] 
class VCI_CAN_OBJ(Structure): 
  _fields_ = [("ID", c_uint),
        ("TimeStamp", c_uint),
        ("TimeFlag", c_ubyte),
        ("SendType", c_ubyte),
        ("RemoteFlag", c_ubyte),
        ("ExternFlag", c_ubyte),
        ("DataLen", c_ubyte),
        ("Data", c_ubyte*8),
        ("Reserved", c_ubyte*3)
        ] 
 
CanDLLName = 'ControlCAN.dll' #DLL是32位的，必须使用32位的PYTHON
canDLL = windll.LoadLibrary(CanDLLName)
print(CanDLLName)
 
ret = canDLL.VCI_OpenDevice(VCI_USBCAN2A, 0, 0)
print(ret)
if ret != STATUS_OK:
  print('调用 VCI_OpenDevice出错\r\n')
 
#初始0通道
vci_initconfig = VCI_INIT_CONFIG(0x80000008, 0xFFFFFFFF, 0,
                 2, 0x00, 0x1C, 0)
ret = canDLL.VCI_InitCAN(VCI_USBCAN2A, 0, 0, byref(vci_initconfig))
if ret != STATUS_OK:
  print('调用 VCI_InitCAN出错\r\n')
 
ret = canDLL.VCI_StartCAN(VCI_USBCAN2A, 0, 0)
if ret != STATUS_OK:
  print('调用 VCI_StartCAN出错\r\n')
 
#初始1通道
ret = canDLL.VCI_InitCAN(VCI_USBCAN2A, 0, 1, byref(vci_initconfig))
if ret != STATUS_OK:
  print('调用 VCI_InitCAN 1 出错\r\n')
 
ret = canDLL.VCI_StartCAN(VCI_USBCAN2A, 0, 1)
if ret != STATUS_OK:
  print('调用 VCI_StartCAN 1 出错\r\n')
 
#通道0发送数据
ubyte_array = c_ubyte*8
a = ubyte_array(1,2,3,4, 5, 6, 7, 64)
ubyte_3array = c_ubyte*3
b = ubyte_3array(0, 0 , 0)
vci_can_obj = VCI_CAN_OBJ(0x0, 0, 0, 1, 0, 0, 8, a, b)
 
ret = canDLL.VCI_Transmit(VCI_USBCAN2A, 0, 0, byref(vci_can_obj), 1)
if ret != STATUS_OK:
  print('调用 VCI_Transmit 出错\r\n')
 
#通道1接收数据
a = ubyte_array(0, 0, 0, 0, 0, 0, 0, 0)
vci_can_obj = VCI_CAN_OBJ(0x0, 0, 0, 1, 0, 0, 8, a, b)
ret = canDLL.VCI_Receive(VCI_USBCAN2A, 0, 1, byref(vci_can_obj), 1, 0)
print(ret)
while ret <= 0:
  print('调用 VCI_Receive 出错\r\n')
  ret = canDLL.VCI_Receive(VCI_USBCAN2A, 0, 1, byref(vci_can_obj), 1, 0)
if ret > 0:
  print(vci_can_obj.DataLen)
  print(list(vci_can_obj.Data))
 
#关闭
canDLL.VCI_CloseDevice(VCI_USBCAN2A, 0)

运行结果输出如下：

ControlCAN.dll
1
1
8

[1, 2, 3, 4, 5, 6, 7, 64]

可以看到从通道1里收通道0发过来的数据，达到这个程序的目的。

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