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_simple(biasLim, fieldLim, gate = 0.0, ivAvg = 1,
cvResistor = 10.0, cvAmp = -1e-6, gateAmp = 9.1788,
srcDelay = 0.01, fieldDelay = 2.0,
nplc = 1, nvmRange = 0.1):
""" Runs the actual experiment. Can be called directly if plotting is
not needed. """
tools.write_log('iv_magField', locals(), filename+'.log')
biasBuffer = tools.get_buffer_size(biasLim[0], biasLim[1], biasLim[2])
bias = np.linspace(biasLim[0], biasLim[1], biasBuffer)
np.savetxt(file, [np.insert(bias, 0, 0.0)], fmt = '%+.6e', delimiter = '\t')
fieldBuffer = tools.get_buffer_size(fieldLim[0], fieldLim[1], fieldLim[2])
fields = np.linspace(fieldLim[0], fieldLim[1], fieldBuffer)
source = keithleypair.IVmax1024("GPIB::22", timeout = 60.0) #keithley object
mag = instruments.oxford_magnet("GPIB::20", rate = 0.2, timeout = 60.0)
daqGate = nidaqmx.AnalogOutputTask() #DAQ output object
daqGate.create_voltage_channel('Dev1/ao0', min_val = -10.0, max_val = 10.0)
daqGate.write([gate/gateAmp])
time.sleep(1.0)
#setup sweep and nanovoltmeter parameters
source.general_setup(beep = True)
currLim = [x/cvResistor for x in biasLim]
source.source_sweep_setup(currLim[0], currLim[1], currLim[2], srcDelay)
source.source_arm_setup()
source.source_trig_setup()
source.voltmeter_channel_setup(nplc, nvmRange, digital_filter = False)
source.voltmeter_trig_setup()
source.voltmeter_buffer_setup(biasBuffer)
realBuffer = int(source.ask(':sour:swe:poin?'))
if int(biasBuffer) != realBuffer:
raise RuntimeError('buffer sizes do not match: {0}, {1}'.format(int(biasBuffer), realBuffer))
#check that everything is setup
print 'source state = {}'.format(source.source_chk_op_evnt_reg())
print 'voltmeter state = {}'.format(source.voltmeter_chk_meas_evnt_reg())
#arm sweep
source.write_serial(':init:imm')
time.sleep(0.25)
source.write(":sour:swe:arm")
time.sleep(3.0)
mag.go_to_field(fieldLim[0], fieldDelay)
for field in fields:
print 'running IV for field = {}T'.format(field)
mag.go_to_field(field, fieldDelay)
data = np.array(source.execute_sweep(ivAvg = ivAvg, timeout = 120.0), dtype = np.floating)
data = data*cvAmp #calculate current from voltage measurement
for i in range(ivAvg): #save all data before averaging
np.savetxt(file, [np.insert(data[i], 0, field)], fmt = '%+.6e', delimiter = '\t')
self.file.flush(); os.fsync(self.file)
print data[i][0], data[i][1], '...', data[i][-2], data[i][-1]
data = data.mean(axis = 0) #average over multiple IV curves for plot
if msvcrt.kbhit():
if ord(msvcrt.getch()) == 113:
print "Program ended by user.\n"
break
print 'Cleaning up...'
source.write(":outp 0") #turn off current source
source.close()
mag.end_at_zero() #set field back to zero
mag.close()
daqGate.write([0.0]) #turn off gate
del mag, source, daqGate
self.file.close()
