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daqIO_VI.py
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daqIO_VI.py
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""" A set of experiments to measure current as a function of several applied voltages
These experiments all use the PCI-6259 DAQ and a current to voltage amplifier. """
from __future__ import division
import time, os, math
import msvcrt
import numpy as np
import matplotlib.pylab as plt
import matplotlib.animation as animation
import nidaqmx
import exptools as tools
from threading import Thread
class DAQIO_gateTest():
""" Uses the DAQ to put out a bias voltage then sweeps the
back gate starting and ending at zero while measuring current with
a current to voltage amplifier.
This should be the safest way to measure the resistance of CNT samples
at room temperature. """
def __init__(self):
""" This doesn't do much other than create the end_run variable. """
self.end_run = False
self.data = [0.0]
def run_simple(self, bias, samples = 1.0, gateDelay = 0.75, field = 0.0,
biasDivider = 1e-3, cvAmp = -1e-6, gateAmp = 9.1788,
filename = 'DAQIO_gateTest_{0:.0f}'.format(time.time())):
""" This runs the actual experiment. It can be called independently of the
run() function. """
tools.write_log('DAQIO_gateTest', locals(), filename+'.log.txt')
file = open(filename+'.dat.txt','a')
self.end_run = False
#setup output channels
bias_channel = 'Dev1/ao0'
bias_out = nidaqmx.AnalogOutputTask()
bias_out.create_voltage_channel(bias_channel, min_val = -10.0, max_val = 10.0)
gate_channel = 'Dev1/ao1'
gate_out = nidaqmx.AnalogOutputTask()
gate_out.create_voltage_channel(gate_channel, min_val = -10.0, max_val = 10.0)
gat = np.arange(0,10.1,0.1)
gates = np.append(gat, [gat[::-1], -gat, -gat[::-1]])
self.data = np.zeros((len(gates), samples+3))
sample_data = np.zeros((samples,1))
#setup input channel
input_channel = 'Dev1/ai0' #if using differential mode this should be the high side
sample_rate = 5000
itask = nidaqmx.AnalogInputTask()
itask.create_voltage_channel(input_channel, terminal = 'diff', min_val = -10.0, max_val = 10.0)
itask.configure_timing_sample_clock(rate = sample_rate, samples_per_channel = samples,
sample_mode = 'finite')
itask.alter_state('commit')
print 'bias turning on...'
bias_out.write(bias/biasDivider)
time.sleep(10.0)
#run experiment
exitGate = 0.0
print 'GO!'
for i, gate in enumerate(gates):
itask.start()
gate_out.write(gate/gateAmp)
time.sleep(gateDelay)
sample_data = itask.read()
itask.wait_until_done()
itask.stop()
self.data[i,0] = gate
self.data[i,1] = sample_data.mean()*cvAmp
self.data[i,2] = bias/self.data[i,1]
self.data[i,3:] = sample_data.transpose()
np.savetxt(file, [self.data[i]], fmt = '%+.6e', delimiter = '\t')
if (msvcrt.kbhit() and ord(msvcrt.getch()) == 113) or self.end_run:
exitGate = gate
print "Program ended by user."
break
bias_out.write(0.0)
bias_out.clear()
gate_out.write(0.0) #turn off gate, should already be at 0
gate_out.clear()
del gate_out, bias_out #delete DAQ object so it can be reused
file.close()
print 'Done.'
def run(self, *args, **kwargs):
""" This will run the animation as the main thread and start a
second thread for the measurement.
Takes all of the arguments and keyword arguments and passes them
to self.run_simple """
runArgs = args
runKwargs = kwargs
def update_current_gate(num, line, ax):
poin = np.count_nonzero(self.data[:,1])
line.set_data(self.data[0:poin,0], self.data[0:poin,1])
ax.set_xlim(np.amin(self.data[0:poin,0]), np.amax(self.data[0:poin,0]))
ax.set_ylim(np.amin(self.data[0:poin,1]),np.amax(self.data[0:poin,1]))
return line, ax
t = Thread(target = self.run_simple, args = runArgs, kwargs = runKwargs)
t.start()
time.sleep(5.0)
while np.count_nonzero(self.data[:,1]) < 3:
time.sleep(0.2) #wait for at least three points to plot
fig = plt.figure()
ax = fig.add_subplot(111)
ax.grid(True)
title_text = plt.title('bias = {0:+.2e}V'.format(args[0]))
line, = ax.plot([], [],'r-o')
plt.xlabel('gate (V)')
plt.ylabel('current (A)')
line_ani = animation.FuncAnimation(fig, update_current_gate, fargs=(line, ax),
interval=1000, blit=False)
plt.show()
self.end_run = True
class DAQIO_stabilityTest():
""" Uses the DAQ to put out a bias voltage then takes data at a few
back gate values while measuring current with
a current to voltage amplifier.
This should help in determining the problems with my gate setup. """
def __init__(self):
""" This doesn't do much other than create the end_run variable. """
self.end_run = False
self.data = 0.0
def run_simple(self, bias, gateDelay = 1.0, measDelay = 0.75,
field = 0.0, biasDivider = 1e-3, cvAmp = -1e-6, gateAmp = 9.1788,
filename = 'DAQIO_gateTest_{0:.0f}'.format(time.time())):
""" This runs the actual experiment. It can be called independently of the
run() function. """
tools.write_log('DAQIO_gateTest', locals(), filename+'.log.txt')
file = open(filename+'.dat.txt','a')
self.end_run = False
sample_rate = 1000
sample_average = 1000
sample_number = 25
#setup output channels
bias_channel = 'Dev1/ao0'
bias_out = nidaqmx.AnalogOutputTask()
bias_out.create_voltage_channel(bias_channel, min_val = -10.0, max_val = 10.0)
gate_channel = 'Dev1/ao1'
gate_out = nidaqmx.AnalogOutputTask()
gate_out.create_voltage_channel(gate_channel, min_val = -10.0, max_val = 10.0)
gates = [0.0, 1.0, 0.0, -1.0, 0.0]
# self.data = np.zeros((, ))
# sample_data = np.zeros((sample_average,1))
#setup input channel
input_channel = 'Dev1/ai0' #if using differential mode this should be the high side
itask = nidaqmx.AnalogInputTask()
itask.create_voltage_channel(input_channel, terminal = 'diff', min_val = -5.0, max_val = 5.0)
itask.configure_timing_sample_clock(rate = sample_rate, samples_per_channel = samples,
sample_mode = 'finite')
itask.alter_state('commit')
print 'bias turning on...'
bias_out.write(bias/biasDivider)
time.sleep(1.0)
#run experiment
exitGate = 0.0
print 'GO!'
for i, gate in enumerate(gates):
gate_out.write(gate/gateAmp)
time.sleep(gateDelay)
for j in range(25):
itask.start()
sample_data = itask.read()
itask.wait_until_done()
itask.stop()
self.data[i,0] = gate
self.data[i,1] = sample_data.mean()*cvAmp
self.data[i,2] = bias/self.data[i,1]
self.data[i,3:] = sample_data.transpose()
np.savetxt(file, [self.data[i]], fmt = '%+.6e', delimiter = '\t')
if (msvcrt.kbhit() and ord(msvcrt.getch()) == 113) or self.end_run:
exitGate = gate
print "Program ended by user."
break
bias_out.write(0.0)
bias_out.clear()
gate_out.write(0.0) #turn off gate, should already be at 0
gate_out.clear()
del gate_out, bias_out #delete DAQ object so it can be reused
file.close()
print 'Done.'
def run(self, *args, **kwargs):
""" This will run the animation as the main thread and start a
second thread for the measurement.
Takes all of the arguments and keyword arguments and passes them
to self.run_simple """
runArgs = args
runKwargs = kwargs
def update_current_gate(num, line, ax):
poin = np.count_nonzero(self.data[:,1])
line.set_data(self.data[0:poin,0], self.data[0:poin,1])
ax.set_xlim(np.amin(self.data[0:poin,0]), np.amax(self.data[0:poin,0]))
ax.set_ylim(np.amin(self.data[0:poin,1]),np.amax(self.data[0:poin,1]))
return line, ax
t = Thread(target = self.run_simple, args = runArgs, kwargs = runKwargs)
t.start()
time.sleep(4.0)
while np.count_nonzero(self.data[:,1]) < 3:
time.sleep(0.2) #wait for at least three points to plot
fig = plt.figure()
ax = fig.add_subplot(111)
ax.grid(True)
title_text = plt.title('bias = {0:+.2e}V'.format(args[0]))
line, = ax.plot([], [],'r-o')
plt.xlabel('gate (V)')
plt.ylabel('current (A)')
line_ani = animation.FuncAnimation(fig, update_current_gate, fargs=(line, ax),
interval=1000, blit=False)
plt.show()
self.end_run = True