# Import functions
from time import sleep
from visa import instrument

# Set keithley current and read voltage
def keithleySetCurrent(current,GPIB):
    try:
        k2400 = instrument('GPIB1::' + str(GPIB),timeout = 20)
    except:
        try:
            k2400 = instrument('GPIB::' + str(GPIB),timeout = 20)
        except:
            print ' no GPIB'
            return
    k2400.write('*rst; status:preset; *cls')
    k2400.write(':SOUR:FUNC CURR')           #Select current source
    k2400.write(':SENS:VOLT:RANG:AUTO ON')   #Auto Measure Range
    k2400.write(':SENS:FUNC "VOLT"')        #Voltage measure function.
    k2400.write(':FORM:ELEM VOLT')          #Voltage reading only.
    k2400.write(':SOUR:CURR:LEV ' + str(current))
    sleep(0.1);
    k2400.write('read?')
    voltage = k2400.read_values()
    return voltage