Agilent 34401A driver

agilent_34401A

from SCPI import SCPI
import time


class Agilent34410ADriver(SCPI):

    def __init__(self):
        SCPI.__init__(self,'COM1','serial')
        #self.scpi_comm("SYST:REM")

        #self.scpi_comm("*RST")
        #self.scpi_comm("CLS")
        #self.scpi_comm("IDN?")
        self.ResetDevice()
        self.DeviceClear()
        self.scpi_comm("*CLS")
        self.ReadSoftwareVersion()



    def configCurrentMeasurement(self):
        self.scpi_comm("CONFIGURE:CURRENT:DC") #Take parameter to also be able to select AC
        return(True)

    def configResistanceMeasurement(self):
        self.scpi_comm("CONFIGURE:RESISTANCE") #Take parameter to also be able to select 4W
        return(True)

    def selectMeasurementFunction(self,function):
        values = ['CAPACITANCE','CONTINUITY','CURRENT','DIODE','FREQUENCY','RESISTANCE','TEMPERATURE','VOLTAGE']
        return_value = False
        if function in values:
            return_value = True
            function_string = "FUNCTION " + "\"" + function + "\""
            self.scpi_comm(function_string)

        return(return_value)

    def readConfiguration(self):
        response = self.scpi_comm("CONFIGURE?")
        response = response.replace(' ',',')
        conf = response.split(',')
        conf_string = "Measurement type: " + conf[0] + "\nRange: " + conf[1] + "\nResolution: " + conf[2]
        return(conf_string)

    def setAutoInputZ(self, auto=False):
        if auto:
            self.scpi_comm("VOLT:IMP:AUTO ON")
        else:
            self.scpi_comm("VOLT:IMP:AUTO OFF")

    # measure 5 times per second and return each measures
    def read(self):
        time.sleep(0.2)
        self.scpi_comm("SYST:REM")
        value = float(self.scpi_comm("MEAS:VOLT:DC?"))
       # value = float(self.scpi_comm("READ?"))

        return value

#--------------------------------------------------------------------------------------------------------------------------------
#stand alone test
##if  __name__ == "__main__":
##    voltmeter=Agilent34410ADriver()
##    volt=0.123456
##    #volt=voltmeter.read()
##    with open('Read_voltage.csv','w') as f:
##        f.write("%f" %(volt))
##    #entry keyboard  to avoid  to go out of the .py
##    raw_input()
#---------------------------------------------------------------------------------------------------------------------------------

reading_loop_test.py

#-------------------------------------------------------------------------------
# Name:        conversion tension - temperature
# Purpose:     calcul de la temperature a partir de la tension mesuree par un thermocouple type K
#
# Author:      Samuel Thomas 
#
# Created:     02/07/2012
# Copyright:   (c) Samuel Thomas 2012
#-------------------------------------------------------------------------------

#------------------------------
import agilent_34410A as dmm
#from agilent_34410A import *
import math
import os
#------------------------------

# Declaration & initialisation variables
driver  = dmm.Agilent34410ADriver()
# INIT AUTO CONFIG VOLT
driver.setAutoInputZ(1)
driver.selectMeasurementFunction('VOLTAGE')

i=0
j=0
voltage=0.0
max_i=1000
temperature=0
differential_temperature=0
#voltage= driver.read()
tab1=[]
tab2=[]
# coefficients for Temperature range: -200 to  0C   /  Voltage range: -5.891 to 0mV
tab1=[0 , 2.51734622*10**-1 ,  -1.1662878 , -1.0833638 , -8.9773540*10**-1 , -3.7342377*10**-1 , -8.6632643*10**-2 , -1.0450598*10**-2 , -5.1920577*10**-4 , 0 ]
# coefficients for Temperature range: 0 to  500C   /  Voltage range: 0 to 20.644mV
tab2=[0 , 2.508355*10 , 7.860106*10**-2 , -2.503131*10**-1 , 8.315270*10**-2 , -1.228034*10**-2 , 9.804036*10**-4 , -4.413030*10**-5 ,  1.057734*10**-6 , -1.052755*10**-8 ,0 ]

#----------------------------------------------------------------------------------------
minV=-100.0
maxV=100.0
avgV=0

# read loop: print 1000 measures
while i < max_i:
    voltage= driver.read()
    # Si la tension mesuree est negative, calcul de la  temperature avec les coeff contenus dans tab1
    if voltage <= 0:
        differential_temperature = tab1[0] + tab1[1]*voltage + tab1[2]*voltage**2 + tab1[3]*voltage**3 + tab1[4]*voltage**4 + tab1[5]*voltage**5 + tab1[6]*voltage**6 + tab1[7]*voltage**7 + tab1[8]*voltage**8 + tab1[9]*voltage**9 + tab1[10]*voltage**10

    # Si la tension mesuree est negative, calcul de la  temperature avec les coeff contenus dans tab2
    else:
        differential_temperature = tab2[0] + tab2[1]*voltage + tab2[2]*voltage**2 + tab2[3]*voltage**3 + tab2[4]*voltage**4 + tab2[5]*voltage**5 + tab2[6]*voltage**6 + tab2[7]*voltage**7 + tab2[8]*voltage**8 + tab2[9]*voltage**9 + tab2[10]*voltage**10

    temperature = differential_temperature + 25

    print temperature

##    #Test Francois
##  #  if (minV<=voltage): minV=voltage
##  # if (maxV>=voltage): maxV=voltage
##  # avgV=avgV+voltage


    i+=1

###Affichage test Francois
###print "max,min,avg: " ,maxV, minV, (avgV/i)

SCPI.py

import time
import serial
import random

class SCPI:

    def __init__(self,device,port):
        self.device = device
        self.port = port
        try:
            if self.port == 'file':
                f = open(self.device, 'w')
            if self.port == 'serial':

# modif-test: on remplace rtscts=true par xonxoff=True
                #f = serial.Serial(self.device, 9600, timeout=1,xonxoff=True)

               f = serial.Serial(self.device, 9600, timeout=1,rtscts=True)
            f.close()
            self.debug = False
        except:
            self.debug = True


    def Remote(self):
        self.scpi_comm("SYST:REM")


    def scpi_comm(self,command):
        if self.debug:
            return str(random.random())
        if self.port == 'file':
            f = open(self.device, 'w')
        if self.port == 'serial':
            #f = serial.Serial(self.device, 9600, timeout=1,xonxoff=True)
            f = serial.Serial(self.device, 9600, timeout=1,rtscts=True)
            command = command + '\n'
        f.write(command)
        f.close()

        time.sleep(0.01)

        return_string = ""
        if command.endswith('?') or command.endswith('?\n'):
            a = ' '
            if self.port == 'file':
               f = open(self.device, 'r')
            if self.port == 'serial':
                f = serial.Serial(self.device, 9600, timeout=1)

            return_string = f.readline()
            while not (ord('a') == 10):
               a = f.read(1)
               return_string += a
        f.close()
        return return_string

    def ReadSoftwareVersion(self, short=False):
        version_string = self.scpi_comm("*IDN?")
        return(version_string)

    def ResetDevice(self):
        self.scpi_comm("*RST")
        return(True)

    def DeviceClear(self):
        self.scpi_comm("*abort")
        return(True)

    def ClearErrorQueue(self):
        error = self.scpi_comm("*ESR?")
        self.scpi_comm("*cls")
        return(error)

When I try to do data logging with this code, I have the "-113" error on the Agilent 34401A, which corresponds to:
"Undefined Header: a command was received that is not valid for this multimeter. You may have misspelled the command or it may not be a valid command. If you are using the short form of the command, remember that it may contain up to four letters".