python-can库基于PCAN-USB使用方法

一、概述

1.介绍

python-can库为Python提供了控制器局域网的支持，为不同的硬件设备提供了通用的抽象，并提供了一套实用程序，用于在CAN总线上发送和接收消息。

支持硬件接口：

Name	Documentation
"socketcan"	SocketCAN
"kvaser"	Kvaser’s CANLIB
"serial"	CAN over Serial
"slcan"	CAN over Serial / SLCAN
"ixxat"	IXXAT Virtual CAN Interface
"pcan"	PCAN Basic API
"usb2can"	USB2CAN Interface
"nican"	NI-CAN
"iscan"	isCAN
"neovi"	neoVI
"vector"	Vector
"virtual"	Virtual
"canalystii"	CANalyst-II
"systec"	SYSTEC interface

2.环境搭建

Python安装：https://www.python.org/ftp/python/3.7.9/python-3.7.9-amd64.exe

PCAN-USB驱动：https://www.peak-system.com/fileadmin/media/files/pcan-basic.zip

库：pip install python-can

3.参考文档

https://python-can.readthedocs.io/en/master/#

二、常用方法

1.接收报文

from can.interfaces.pcan.pcan import PcanBus

def bus_recv():
    """轮询接收消息"""
    try:
        while True:
            msg = bus.recv(timeout=100)
            print(msg)
    except KeyboardInterrupt:
        pass

if __name__ == '__main__':
    bus = PcanBus(channel='PCAN_USBBUS1', bitrate=500000)
    bus_recv()

2.发送报文

from can.interfaces.pcan.pcan import PcanBus

def bus_send():
    """can消息发送"""
    while True:
        time.sleep(0.02)
        try:
            bus.send(msg)
            print("消息发送 {}".format(bus.channel_info))
        except can.CanError:
            print("消息未发送")

if __name__ == '__main__':
    msg = can.Message(arbitration_id=0x181DFF00, data=[0xEE, 0xFE, 0xFE, 0xFF, 0xFE, 0xFF, 0xFF, 0xFE],
                      is_extended_id=True)  # 报文
    bus = PcanBus(channel='PCAN_USBBUS1', bitrate=500000)
    bus_send()

3.定期发送报文

def bus_send_periodic():
    """周期发送报文"""
    print("开始每200毫秒发送一条消息。持续时间10s")
    task = bus.send_periodic(msg, 1.5)  # 定期发送
    if not isinstance(task, can.ModifiableCyclicTaskABC):  # 断言task类型
        print("此接口似乎不支持")
        task.stop()
        return
    time.sleep(5)  # 持续时间
    print("发送完成")
    print("更改运行任务的数据以99开头")
    msg.data[0] = 0x99
    task.modify_data(msg)  # 修改data首字节
    time.sleep(10)

    task.stop()
    print("停止循环发送")
    print("将停止任务的数据更改为单个 ff 字节")
    msg.data = bytearray([0xff])  # 重新定向data
    msg.dlc = 1  # 定义data长度
    task.modify_data(msg)  # 修改data
    time.sleep(10)
    print("重新开始")
    task.start()  # 重新启动已停止的周期性任务
    time.sleep(10)
    task.stop()
    print("完毕")

if __name__ == '__main__':
    msg = can.Message(arbitration_id=0x181DFF00, data=[0xEE, 0xFE, 0xFE, 0xFF, 0xFE, 0xFF, 0xFF, 0xFE],
                      is_extended_id=True)  # 报文
    bus = PcanBus(channel='PCAN_USBBUS1', bitrate=500000)
    bus_send_periodic()

4.循环收发消息

from can.interfaces.pcan.pcan import PcanBus

def send_cyclic(stop_event):
    """循环发送消息"""
    print("开始每1秒发送1条消息")
    start_time = time.time()
    while not stop_event.is_set():
        msg.timestamp = time.time() - start_time
        bus.send(msg)
        print(f"tx: {msg}")
        time.sleep(1)
    print("停止发送消息")

def receive(stop_event):
    """循环接收消息"""
    print("开始接收消息")
    while not stop_event.is_set():
        rx_msg = bus.recv(1)
        if rx_msg is not None:
            print(f"rx: {rx_msg}")
    print("停止接收消息")

def send_and_recv_msg():
    """发送一个消息并接收一个消息,需要双通道CAN"""
    stop_event = threading.Event()
    t_send_cyclic = threading.Thread(target=send_cyclic, args=(stop_event,))
    t_receive = threading.Thread(target=receive, args=(stop_event,))
    t_receive.start()
    t_send_cyclic.start()
    try:
        while True:
            time.sleep(0)  # yield
    except KeyboardInterrupt:
        pass  # 正常退出
    stop_event.set()
    time.sleep(0.5)

if __name__ == '__main__':
    msg = can.Message(arbitration_id=0x181DFF00, data=[0xEE, 0xFE, 0xFE, 0xFF, 0xFE, 0xFF, 0xFF, 0xFE],
                      is_extended_id=True)  # 报文
    bus = PcanBus(channel='PCAN_USBBUS1', bitrate=500000)
    send_and_recv_msg()