# gpib.py
# pull in data from an HP 34401A bench multimeter using a Prologix GPIB-USB adapter
# 2019, Zach Fredin, MIT CBA

import serial
import tkinter as tk
from tkinter import StringVar
import sys
import time

if (len(sys.argv) != 2):
   print ("to use, type python3 gpib.py /dev/ttyUSBx")
   sys.exit()
port = sys.argv[1]

ser = serial.Serial(port,9600)
ser.setDTR()

class Application(tk.Frame):
    def __init__(self, master=None):
        super().__init__(master)
        self.master = master
        self.pack()
        self.create_widgets()

    def create_widgets(self):
        self.read = tk.Button(self)
        self.read["text"] = "get reading"
        self.read["command"] = self.get_reading
        self.read.pack(side="top")

        self.label_text = StringVar()
        self.label_text.set("")
        self.label = tk.Label(self, text=self.label_text)
        self.label.pack()

        self.quit = tk.Button(self, text="quit", fg="red",
                              command=self.master.destroy)
        self.quit.pack(side="bottom")

    def get_reading(self):
        val = ""
        out = ""
        ser.write(b'D2how to make\r')
        ser.write(b'OUTPUT 723; "H1"\r')
        time.sleep(3)
        ser.write(b'++read\r')
        while val != '\r':
            val = ser.read().decode()
            out += val
        print (out)

root = tk.Tk()
app = Application(master=root)
app.mainloop()