KEITHLEY 2636A ERROR CODE -420

Hello Guys, i am the beginner to use KEITHLEY 2636A. At first i want to test our instrument. I connected a 10 KOhm resistor to KEITHLEY source and i want to conduct device under test (DUT). i write the below mentioned code in python to communicate between PC and KEITHLEY. But, when I run the python(pyvisa) code the KEITHLEY 2636A screen shows some ERROR CODE -420 (Query UNTERMINATED). what is this error means and how we can resolve this error? Your experience and guideance will be appreceated. thanks

Even it shows me result a the end, but still i saw ERROR CODE -420 (Query UNTERMINATED) on the KEITHLEY screen during the measurements.

here is the code.

import pyvisa

import numpy as np

import time

import matplotlib.pyplot as plt

# set up the instrument

rm = pyvisa.ResourceManager()

keithley = rm.open_resource("GPIB0::26::INSTR")  # Replace with your instrument address

keithley.write("smua.reset()")

keithley.write("smua.source.func = smua.OUTPUT_DCVOLTS")

keithley.write("smua.source.autorangei = smua.AUTORANGE_ON")

keithley.write("smua.source.autorangev = smua.AUTORANGE_ON")

keithley.write("smua.source.limiti = 10e-3")  # Set current compliance to 10 mA

keithley.write("smua.measure.autorangei = smua.AUTORANGE_ON")

keithley.write("smua.measure.autorangev = smua.AUTORANGE_ON")

# set up the sweep parameters

start_voltage = 0

stop_voltage = 10

num_points = 21

sweep_time = 1e-3

current_limit = 10e-3

# generate the voltage values

voltage_values = np.linspace(start_voltage, stop_voltage, num_points)

# set the initial voltage

keithley.write("smua.source.levelv = {}".format(start_voltage))

keithley.write("smua.source.output = smua.OUTPUT_ON")

time.sleep(0.1)  # Wait for output to settle

# sweep the voltage and measure the current

current_values = np.empty_like(voltage_values)

time.sleep(0.5)  # Wait for the instrument to settle

for i, voltage in enumerate(voltage_values):

    keithley.write("smua.source.levelv = {}".format(voltage))

    time.sleep(sweep_time/num_points)  # Wait for next data point

    current_values[i] = float(keithley.query("smua.measure.i()"))

    time.sleep(0.1)  # Wait for instrument to settle

# turn off the output

keithley.write("smua.source.output = smua.OUTPUT_OFF")

# plot the data

plt.plot(voltage_values, current_values)

plt.xlabel("Voltage (V)")

plt.ylabel("Current (A)")

plt.show()