Multimeter_Temp.pyw

#!/usr/bin/python
from tkinter import *
import time
import serial
import serial.tools.list_ports
import sys
import kconvert

top = Tk()
top.resizable(0,0)
top.title("Fluke_45/Tek_DMM4020 K-type Thermocouple")

#ATTENTION: Make sure the multimeter is configured at 9600 baud, 8-bits, parity none, 1 stop bit, echo Off

CJTemp = StringVar()
Temp = StringVar()
DMMout = StringVar()
portstatus = StringVar()
DMM_Name = StringVar()
connected=0
global ser
   
def Just_Exit():
    top.destroy()
    try:
        ser.close()
    except:
        dummy=0

def update_temp():
    global ser, connected
    if connected==0:
        top.after(5000, FindPort) # Not connected, try to reconnect again in 5 seconds
        return
    try:
        strin = ser.readline() # Read the requested value, for example "+0.234E-3 VDC"
        strin = strin.rstrip()
        strin = strin.decode()
        print(strin)
        ser.readline() # Read and discard the prompt "=>"
        if len(strin)>1:
            if strin[1]=='>': # Out of sync?
                strin = ser.readline() # Read the value again
        ser.write(b"MEAS1?\r\n") # Request next value from multimeter
    except:
        connected=0
        DMMout.set("----")
        Temp.set("----");
        portstatus.set("Communication Lost")
        DMM_Name.set ("--------")
        top.after(5000, FindPort) # Try to reconnect again in 5 seconds
        return
    strin_clean = strin.replace("VDC","") # get rid of the units as the 'float()' function doesn't like it
    if len(strin_clean) > 0:      
       DMMout.set(strin.replace("\r", "").replace("\n", "")) # display the information received from the multimeter

       try:
           val=float(strin_clean)*1000.0 # Convert from volts to millivolts
           valid_val=1;
       except:
           valid_val=0

       try:
          cj=float(CJTemp.get()) # Read the cold junction temperature in degrees centigrade
       except:
          cj=0.0 # If the input is blank, assume cold junction temperature is zero degrees centigrade

       if valid_val == 1 :
           ktemp=round(kconvert.mV_to_C(val, cj),1)
           if ktemp < -200:  
               Temp.set("UNDER")
           elif ktemp > 1372:
               Temp.set("OVER")
           else:
               Temp.set(ktemp)
       else:
           Temp.set("----");
    else:
       Temp.set("----");
       connected=0;
    top.after(500, update_temp) # The multimeter is slow and the baud rate is slow: two measurement per second tops!

def FindPort():
   global ser, connected
   try:
       ser.close()
   except:
       dummy=0
       
   connected=0
   DMM_Name.set ("--------")
   portlist=list(serial.tools.list_ports.comports())
   for item in reversed(portlist):
      portstatus.set("Trying port " + item[0])
      top.update()
      try:
         ser = serial.Serial(item[0], 9600, timeout=0.5)
         ser.write(b"\x03") # Request prompt from possible multimeter
         pstring = ser.readline() # Read the prompt "=>"
         pstring=pstring.rstrip()
         pstring=pstring.decode()
         # print(pstring)
         if len(pstring) > 1:
            if pstring[1]=='>':
               ser.timeout=3  # Three seconds timeout to receive data should be enough
               portstatus.set("Connected to " + item[0])
               ser.write(b"VDC; RATE S; *IDN?\r\n") # Measure DC voltage, set scan rate to 'Slow' for max resolution, get multimeter ID
               devicename=ser.readline()
               devicename=devicename.rstrip()
               devicename=devicename.decode()
               DMM_Name.set(devicename.replace("\r", "").replace("\n", ""))
               ser.readline() # Read and discard the prompt "=>"
               ser.write(b"MEAS1?\r\n") # Request first value from multimeter
               connected=1
               top.after(1000, update_temp)
               break
            else:
               ser.close()
         else:
            ser.close()
      except:
         connected=0
   if connected==0:
      portstatus.set("Multimeter not found")
      top.after(5000, FindPort) # Try again in 5 seconds

Label(top, text="Cold Junction Temperature:").grid(row=1, column=0)
Entry(top, bd =1, width=7, textvariable=CJTemp).grid(row=2, column=0)
Label(top, text="Multimeter reading:").grid(row=3, column=0)
Label(top, text="xxxx", textvariable=DMMout, width=20, font=("Helvetica", 20), fg="red").grid(row=4, column=0)
Label(top, text="Thermocouple Temperature (C)").grid(row=5, column=0)
Label(top, textvariable=Temp, width=5, font=("Helvetica", 100), fg="blue").grid(row=6, column=0)
Label(top, text="xxxx", textvariable=portstatus, width=40, font=("Helvetica", 12)).grid(row=7, column=0)
Label(top, text="xxxx", textvariable=DMM_Name, width=40, font=("Helvetica", 12)).grid(row=8, column=0)
Button(top, width=11, text = "Exit", command = Just_Exit).grid(row=9, column=0)

CJTemp.set ("22")
DMMout.set ("NO DATA")
DMM_Name.set ("--------")

top.after(500, FindPort)
top.mainloop()