GPIB voltage logging with a Fluke 8842A

logging.py

#!/usr/bin/python

# reads a voltage each 10 seconds and prints it
# sample output:
#
# instrument      FLUKE,8842A,0,V3.0
# start   Sat Oct  5 05:36:48 2019
# 
# time    voltage
# 0       4.191300
# 10      4.190900
# 20      4.190700
# 30      4.190400
# 40      4.172100
# 50      4.161700
# 60      4.154700
#
# the values are separated by tabs, can be saved as CSV and imported in a spreadsheet program

import Gpib
import time
import sys

# define time step in seconds
step = 10

# GPIB Address = 24
inst = Gpib.Gpib(0,24, timeout=60) 
inst.clear() 

# show instrument name and version
inst.write("G8")
print("instrument\t" + inst.read().strip())

# configure for VDC measurement
inst.write("F1")

# 20V range
inst.write("R3")

# slow rate
inst.write("S0")

# external trigger by GPIB command "?" for measurment
inst.write("T1")

# trigger first measurement
inst.write("?")

# read current time, start measurement loop about 2 seconds later
t0 = time.time() + 2
t0 = int(t0)
start = t0 + 2 * step

# log start time
print("start\t%s\n" % time.ctime(t0 + step))

# measurement loop
print("time\tvoltage")
first = True
while True:
    # wait until next time slot
    t = time.time()
    time.sleep(t0 - t)
    
    # measure exactly each step seconds
    t0 = t0 + step
    
    # read measurement and print it with timestamp
    volt = float(inst.read().strip())

    # trigger next measurement
    inst.write("?")

    # print it with time in seconds, ignore first measurement
    if first:
        first = False
    else:
        print("%i\t%f\t" % (int(t0 - start), volt))
        sys.stdout.flush()