python中使用cantools和can工具包解析blf文件

一、工具包安装

pip install cantools python-can

二、解析blf文件

一般情况下,解析blf需要dbc文件,当然其实不用dbc也可以,只不过解析比较麻烦,推荐还是配合dbc解析,这个也是我们最常用的办法。所以要用dbc,需要先加载dbc文件,这里需要cantools,代码:

import cantools
import can
dbc_file = r"C:\Users\master01\Downloads\blf_conf\FS04通用_TBOX(1).dbc"
dbc = cantools.db.load_file(dbc_file)

加载完dbc文件,就可以解析blf文件了,代码

f = r"C:\Users\master01\Downloads\blfdata\问题blf\1.17-9-10.blf"
log_data = can.BLFReader(f)
for msg in log_data:
    print(msg)

打印结果是这样的

Timestamp: 1673917200.026000        ID: 0301    S Rx                DL:  8    1d b0 41 54 07 02 00 00     Channel: 0
Timestamp: 1673917200.026000        ID: 070b    S Rx                DL:  8    00 c8 0c b6 24 b8 24 b8     Channel: 0
Timestamp: 1673917200.028000        ID: 0322    S Rx                DL:  8    00 00 00 00 00 00 03 00     Channel: 0
Timestamp: 1673917200.126000        ID: 030d    S Rx                DL:  8    00 14 00 00 00 00 00 00     Channel: 0
Timestamp: 1673917200.126000        ID: 0320    S Rx                DL:  8    06 b1 00 00 00 00 07 00     Channel: 0
Timestamp: 1673917200.127000        ID: 0708    S Rx                DL:  8    00 48 00 48 00 08 00 32     Channel: 0
Timestamp: 1673917200.129000        ID: 0712    S Rx                DL:  8    00 06 81 0d 21 05 00 00     Channel: 0
Timestamp: 1673917200.271000    ID: 1821a7c1    X Rx                DL:  8    02 2f 00 00 00 00 00 00     Channel: 0
Timestamp: 1673917200.321000        ID: 0110    S Rx                DL:  8    05 36 16 67 00 09 20 6b     Channel: 0
Timestamp: 1673917200.322000        ID: 0111    S Rx                DL:  8    16 5d 00 00 d4 00 20 bf     Channel: 0
Timestamp: 1673917200.322000        ID: 0112    S Rx                DL:  8    49 32 00 10 00 16 6d 4c     Channel: 0
Timestamp: 1673917200.326000        ID: 0300    S Rx                DL:  8    00 3a c2 f8 00 00 00 00     Channel: 0
Timestamp: 1673917200.326000        ID: 0710    S Rx                DL:  8    00 00 00 00 00 00 00 00     Channel: 0
Timestamp: 1673917200.427000        ID: 0709    S Rx                DL:  8    0e 02 0e b0 4a 0c ff fe     Channel: 0
Timestamp: 1673917200.427000        ID: 070a    S Rx                DL:  8    11 51 1f fd 46 de 1c 83     Channel: 0
Timestamp: 1673917200.428000        ID: 0711    S Rx                DL:  8    02 df 00 09 02 d5 00 d4     Channel: 0
Timestamp: 1673917200.438000        ID: 0308    S Rx                DL:  8    03 22 0a 3c 0a 00 00 2a     Channel: 0
Timestamp: 1673917200.550000        ID: 03a1    S Rx                DL:  8    00 00 06 b1 00 00 15 00     Channel: 0
Timestamp: 1673917200.550000        ID: 03a2    S Rx                DL:  8    00 00 00 00 00 00 05 00     Channel: 0
Timestamp: 1673917200.633000        ID: 0270    S Rx                DL:  8    00 67 67 00 00 00 00 a2     Channel: 0
Timestamp: 1673917200.638000        ID: 0307    S Rx                DL:  8    41 14 03 c0 36 00 00 03     Channel: 0
Timestamp: 1673917200.638000        ID: 0309    S Rx                DL:  8    1c 1c 1c 1c 1c 1c c3 50     Channel: 0
Timestamp: 1673917200.655000        ID: 03a0    S Rx                DL:  8    06 b1 00 00 00 00 15 00     Channel: 0
Timestamp: 1673917200.657000        ID: 030a    S Rx                DL:  8    00 00 00 00 00 00 00 00     Channel: 0

可以发现,时间戳解析出来了,其它的数据都是16进制,没法直接看,当然我们如果熟悉blf格式,可以自己把数据还原出来,但是既然已经用第三方库,我们当然就不用自己解析了,而且仔细观察一下即可发现,之前的加载dbc并没有用上,所以这时一个重要的函数登场了,那就是dbc.decode_message(id,data),具体代码如下

decoded = {}
for msg in logdata:
    try:
        dec = dbc.decode_message(msg.arbitration_id, msg.data)
        if dec:
            for key, data in dec.items():
                if key not in decoded:
                    decoded[key] = []
                decoded[key].append([msg.timestamp, data])
    except:
        pass

因为我这里是最后把数据解析出来转成mf4了,所以构建了一个decoded字典,每个key里记一个信号,熟悉mf4的应该知道,mf4里每个信号主要包含两部分,一个是时间戳,一个是数据,有了这两个,我们就可以创建mf4文件了,最后放上创建mf4的代码

from asammdf import MDF,Signal
sigs = []
for k,v in decoded.items():
    timestamps = [i[0] for i in v]
    data = [i[1] for i in v]
    s = Signal(data,timestamps,name=k)
    sigs.append(s)

mdf = MDF()
mdf.append(sigs)
mdf.save("xx.mf4",overwrite=True)

这样就实现了blf文件的解析与转换,当然,转换的格式很自由,只要熟悉相应的格式,比如csv,hdf5,xlsx,json,pickle都可以,因为我们已经拿到原始数据了,保存成什么格式就很简单了。

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