pythonpandasfilematplotlibcan-bus
Reading a CAN .asc file and plot specific data from it
I am quite new to this datascience and python stuff i have a code that looks fine at first sight and also runs without problems but it doesnt give me the outcome i expect. the data i want in my tables arent inside at all so it doesnt plot in the end.
import pandas as pd
import matplotlib.pyplot as plt
# Step 1: Read the .asc file, ignoring the header and using varying spaces as separators
file_path = 'StartupElektroMode.asc'
data = []
try:
with open(file_path, 'r') as file:
lines = file.readlines()
except FileNotFoundError:
print(f"Error: The file'{file_path}' was not found")
timestamps = []
voltage_data = []
current_data = []
for line in lines[6:]:
parts = line.split()
if len(parts) >= 3:
timestamp = parts[0]
can_id = parts[2]
voltage_hex = None
current_hex = None
if can_id == '1E3' and len(parts) > 12:
voltage_hex = parts[13]
elif can_id == '4E3' and len(parts) > 13:
current_hex = parts[12]
# Step 2: Convert the hex values to decimal
for item in data:
if voltage_hex is not None:
first_digit = int(voltage_hex[0], 16)
second_digit = int(voltage_hex[1], 16)
voltage = (first_digit * 256 + second_digit) * 0.25
voltage_data.append(voltage)
if current_hex is not None:
first_digit = int(current_hex[0], 16)
second_digit = int(current_hex[1], 16)
current = (first_digit * 256 + second_digit) * 0.25
current_data.append(current)
data = {'Time': timestamps, 'Voltage': voltage_data, 'Current': current_data}
# Step 3: Create Pandas DataFrame
df = pd.DataFrame(data)
# Step 4: Plot Voltage and Current over time
plt.figure(figsize=(12, 6))
plt.plot(timestamps, voltage_data, label='Voltage (1E3)')
plt.title('Voltage Over Time')
plt.xlabel('Time')
plt.ylabel('Voltage (V)')
plt.legend()
plt.grid()
plt.plot(timestamps, current_data, label='Current (4E3)')
plt.title('Current Over Time')
plt.xlabel('Time')
plt.ylabel('Current (A)')
plt.legend()
plt.grid()
plt.tight_layout()
plt.show()
file.close()
here a part of the file i try to read
0.028121 1 CFF4912x Rx d 8 00 00 03 00 11 00 00 00 Length = 280152 BitCount = 144 ID = 218056978x
0.029376 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.029492 1 206 Rx d 1 04 Length = 107914 BitCount = 58 ID = 518
0.031802 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.031918 1 206 Rx d 1 04 Length = 107914 BitCount = 58 ID = 518
0.034060 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239683 BitCount = 124 ID = 1302
0.034176 1 206 Rx d 1 04 Length = 107929 BitCount = 58 ID = 518
0.036204 1 1E3 Rx d 8 01 59 00 00 00 00 1A 05 Length = 235910 BitCount = 122 ID = 483
0.036456 1 100 Rx d 8 00 00 00 00 00 00 00 08 Length = 243683 BitCount = 126 ID = 256
0.036703 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.036819 1 206 Rx d 1 04 Length = 107680 BitCount = 58 ID = 518
0.037249 1 2E3 Rx d 8 C4 C3 00 64 19 15 01 01 Length = 221668 BitCount = 115 ID = 739
0.038204 1 3E3 Rx d 8 68 01 38 04 03 00 00 00 Length = 235910 BitCount = 122 ID = 995
0.038885 1 144 Rx d 8 00 00 00 00 00 00 01 00 Length = 241668 BitCount = 125 ID = 324
0.039133 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.039249 1 206 Rx d 1 04 Length = 107914 BitCount = 58 ID = 518
0.039487 1 4E3 Rx d 8 1E 00 8C 00 00 F8 FF 00 Length = 229910 BitCount = 119 ID = 1251
0.041397 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.041513 1 206 Rx d 1 04 Length = 107914 BitCount = 58 ID = 518
0.043613 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.043729 1 206 Rx d 1 04 Length = 107929 BitCount = 58 ID = 518
0.045825 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.045941 1 206 Rx d 1 04 Length = 107914 BitCount = 58 ID = 518
0.046193 1 100 Rx d 8 00 00 00 00 00 00 00 08 Length = 243668 BitCount = 126 ID = 256
0.047126 1 CF00400x Rx d 8 F8 7D 7D 00 00 00 F0 7D Length = 280167 BitCount = 144 ID = 217056256x
Any suggestions what I could do or where my problem might be
Solution
Your voltage and current data are received in different frames and thus always have different timestamps. A dataframe isn't quite adapted to plot your data since you would end up with a lot of NaN values.
Build timestamp lists in parallel to voltage and current and plot them both (on one or different graphs). Also it seems that your hex conversion is wrong (or are current/voltage meant to be spread on two bytes?) I slightly modified your example to have more than one datapoint:
import pandas as pd
import matplotlib.pyplot as plt
from io import StringIO
file = StringIO("""" 0.028121 1 CFF4912x Rx d 8 00 00 03 00 11 00 00 00 Length = 280152 BitCount = 144 ID = 218056978x
0.029376 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.029492 1 206 Rx d 1 04 Length = 107914 BitCount = 58 ID = 518
0.031802 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.031918 1 206 Rx d 1 04 Length = 107914 BitCount = 58 ID = 518
0.034060 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239683 BitCount = 124 ID = 1302
0.034176 1 206 Rx d 1 04 Length = 107929 BitCount = 58 ID = 518
0.036204 1 1E3 Rx d 8 01 59 00 00 00 00 1A 05 Length = 235910 BitCount = 122 ID = 483
0.036456 1 100 Rx d 8 00 00 00 00 00 00 00 08 Length = 243683 BitCount = 126 ID = 256
0.036703 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.036819 1 206 Rx d 1 04 Length = 107680 BitCount = 58 ID = 518
0.037249 1 2E3 Rx d 8 C4 C3 00 64 19 15 01 01 Length = 221668 BitCount = 115 ID = 739
0.038204 1 3E3 Rx d 8 68 01 38 04 03 00 00 00 Length = 235910 BitCount = 122 ID = 995
0.038885 1 144 Rx d 8 00 00 00 00 00 00 01 00 Length = 241668 BitCount = 125 ID = 324
0.039133 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.039249 1 206 Rx d 1 04 Length = 107914 BitCount = 58 ID = 518
0.039487 1 4E3 Rx d 8 1E 00 8C 00 00 F8 FF 00 Length = 229910 BitCount = 119 ID = 1251
0.041397 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.041513 1 206 Rx d 1 04 Length = 107914 BitCount = 58 ID = 518
0.043613 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.043729 1 206 Rx d 1 04 Length = 107929 BitCount = 58 ID = 518
0.045825 1 516 Rx d 8 00 00 00 00 00 00 00 00 Length = 239668 BitCount = 124 ID = 1302
0.045941 1 206 Rx d 1 04 Length = 107914 BitCount = 58 ID = 518
0.046193 1 100 Rx d 8 00 00 00 00 00 00 00 08 Length = 243668 BitCount = 126 ID = 256
0.046194 1 1E3 Rx d 8 01 59 00 00 00 00 1A 0F Length = 235910 BitCount = 122 ID = 483
0.046195 1 4E3 Rx d 8 1E 00 8C 00 00 F8 2F 00 Length = 229910 BitCount = 119 ID = 1251
0.047126 1 CF00400x Rx d 8 F8 7D 7D 00 00 00 F0 7D Length = 280167 BitCount = 144 ID = 217056256x""")
lines = file.readlines()
t_volt = []
voltage_data = []
t_curr = []
current_data = []
for line in lines:
parts = line.split()
if len(parts) >= 3:
timestamp = parts[0]
can_id = parts[2]
voltage_hex = None
current_hex = None
if can_id == '1E3' and len(parts) > 12:
voltage_hex = parts[13]
elif can_id == '4E3' and len(parts) > 13:
current_hex = parts[12]
# Convert the hex values to decimal
if voltage_hex is not None:
voltage = int(voltage_hex, 16) * 0.25
voltage_data.append(voltage)
t_volt.append(float(parts[0]))
if current_hex is not None:
current = int(current_hex, 16) * 0.25
current_data.append(current)
t_curr.append(float(parts[0]))
# Plot Voltage and Current over time
fig, ax = plt.subplots(figsize=(12, 6))
ax.plot(t_volt, voltage_data, label='Voltage (1E3)')
ax.set_title('Voltage and Current Over Time')
ax.set_xlabel('Time')
ax.set_ylabel('Voltage (V)')
ax2 = ax.twinx()
ax2.plot(t_curr, current_data, color='orange', label='Current (4E3)')
ax2.set_ylabel('Current (A)')
fig.legend()
ax.grid()
fig.tight_layout()
plt.show()
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