psudmm.py

import sys
import time
import socket
import datetime
import numpy as np
import matplotlib.pyplot as plt

if len(sys.argv) != 4:
    print("Usage: psudmm.py <Channel> <Max Voltage> <Voltage Step>")
    sys.exit(1)

channel = sys.argv[1]
max_voltage = float(sys.argv[2])
voltage_step = float(sys.argv[3])

print("Channel", channel)
print("0 to {}V in {}V steps".format(max_voltage, voltage_step))

targets = np.arange(0, max_voltage, voltage_step)
psu_readings = np.zeros(targets.size)
dmm_readings = np.zeros(targets.size)

dmm = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
psu = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
dmm.connect(("dmm.bench", 5025))
psu.connect(("psu.bench", 5025))

dmm.send("SYST:LAB \"PSU {}\"\r\n".format(channel).encode())
if max_voltage < 10:
    dmm.send(b"CONF:VOLT:DC 10V\r\n")
elif max_voltage < 100:
    dmm.send(b"CONF:VOLT:DC 100V\r\n")
else:
    raise RuntimeError("Don't know how to handle max_voltage={}"
                       .format(max_voltage))
dmm.send(b"SAMP:COUN 5\r\n")

psu.send("INST {}\r\n".format(channel).encode())
psu.send(b"CURR 0.1\r\n")
psu.send(b"VOLT 0\r\n")
psu.send(b"OUTP ON\r\n")

time.sleep(0.1)

print("Target  \tPSU     \tDMM")

for idx, target in enumerate(targets):
    psu.send("VOLT {:.3f}\r\n".format(target).encode())
    time.sleep(0.5)
    dmm.send(b"READ?\r\n")
    readings = [float(x) for x in dmm.recv(1024).decode().split(",")]
    dmm_readings[idx] = np.mean(readings[1:])
    psu.send(b"MEAS:VOLT?\r\n")
    psu_readings[idx] = float(psu.recv(1024).decode())
    print("{:.6f}\t{:.6f}\t{:.6f}"
          .format(target, psu_readings[idx], dmm_readings[idx]))

psu.send(b"OUTP OFF\r\n")
dmm.send(b"SYST:BEEP\r\n")

supply_err = dmm_readings - targets
readback_err = psu_readings - dmm_readings

plt.plot(targets, supply_err*1000, 'b-x', label="Supply Error")
plt.plot(targets, readback_err*1000, 'g-x', label="Readback Error")
plt.ylabel("Error, mV")
plt.xlabel("Target, V")
plt.legend(loc='lower left')
plt.grid()
plt.title("E36312A {}".format(channel))

date = datetime.datetime.utcnow().strftime("%Y%d%mT%H%M%SZ")

plt.savefig("e36312a_{}_{}.png".format(channel.lower(), date))

np.savez("e36312a_{}_{}.npz".format(channel.lower(), date),
         targets=targets, psu_readings=psu_readings, dmm_readings=dmm_readings)

screenshot_psu.py

import io
import sys
import requests
from PIL import Image

if len(sys.argv) != 2:
    print("Usage: screenshot_psu.py <filename>")
    sys.exit(1)

# first log in
requests.get("http://psu.bench/cgi/login?pass=keysight")

# now download screenshot
r = requests.get("http://psu.bench/get/screenshot.bmp")

# convert to PNG and save
img = Image.open(io.BytesIO(r.content))
img.save(sys.argv[1])