import serial

# Get data from serial port:
ser = serial.Serial('COM5',9600)    # check COM port number

# Set variables:
n=0
setPoint=[]
photoSignal=[]

# Read data:
while n<800:                        # number of data points collected
    SP = int(ser.readline())
    PS = int(ser.readline())
    setPoint.append(SP)
    photoSignal.append(PS)
    n+=1
   
ser.close()                         # close serial port

#%% Plotting the data:
import matplotlib.pyplot as plt

plt.plot(setPoint,lw=4.0,label='Set Point')
plt.plot(photoSignal,label='Photo Signal')
plt.ylabel('Photocell Input')
plt.xlabel('Data Points')
plt.title('PID Controlled LED Signal')
plt.legend(loc='lower right')
plt.show()