Pyserial prints empty b ' ' from a USB serial port

Question

I seem to be having an problem, when I run this Python 3.5 script It's for USB serial controlled device:

import serial
import time

ser1 = serial.Serial('/dev/tty.usbserial', 115200, timeout=0.1)

def setupMode():
    ser1.write(b'$PF,200\r\n')
    ser1.write(b'$PO,20\r\n')

setupMode()


def startMeasurments():
    ser1.write(b'$GO\r\n')

startMeasurments()

def checkUnit():
    ser1.write(b'$US\r\n')

checkUnit()

while True:
    data = ser1.read(9999)
    print ('Got:', data)

time.sleep(0.1)
ser1.close()

I get these results:

python maintest.py
Got: b''
Got: b''
Got: b''
Got: b''
Got: b''
Got: b''
Got: b''
Got: b''
Got: b''
Got: b''

the frequency of the printed data seems correct, and when tested the command:

ser1.write(xxxxx)

it triggers the device and outputs the necessary data to manufacturer provided software, so it's working fine- just the python output seems not to be working. How could i tackle this?

Answer 1

Maybe this will work:

while True:
    data = ''
    while ser1.inWaiting()>0:
        data += ser1.read(1)
    if data:
        print ('Got:', data)