Code to read data from the serial port and plot it.

serialplot

#!/usr/bin/python
# -*- coding: utf-8 -*-

from pyqtgraph.Qt import QtGui, QtCore
import numpy as np
import pyqtgraph as pg
from pyqtgraph.ptime import time
import serial

app = QtGui.QApplication([])

p = pg.plot()
p.setWindowTitle('live plot from serial')
curve = p.plot()

data = [0]
raw=serial.Serial("/dev/ttyACM0",9600)
raw.open()

def update():
    global curve, data
    line = raw.readline()
    data.append(int(line))
    xdata = np.array(data, dtype='float64')
    curve.setData(xdata)
    app.processEvents()

timer = QtCore.QTimer()
timer.timeout.connect(update)
timer.start(0)

if __name__ == '__main__':
    import sys
    if (sys.flags.interactive != 1) or not hasattr(QtCore, 'PYQT_VERSION'):
        QtGui.QApplication.instance().exec_()

@srikarpv

If you are on linux, you can use picocom to read the serial data and pipe it into a file.

i.e.:
picocom /dev/ttyACM0 > log.csv

Hit ctrl-c if you want to stop logging. You can use tee to see and log the stream at the same time.

If you want to do it in python, you just have to take the above code and write the variable line to a file.