def __init__(self, analog_channels='/Dev1/ao0:2', output_counter='/Dev1/Ctr0', voltage_range=(10,10)):
self._analog_channels = analog_channels
self._output_counter = output_counter
self._voltage_range=voltage_range
# we start with default duty cycle
self._duty_cycle = 0.5
self._seconds_per_point = 1000.
self._transfer_timeout = 1.0
# we start with unknown length
self._length = None
# create nidaq tasks
self._n_written = ctypes.c_long()
self._ao_task = ctypes.c_ulong()
self._co_task = ctypes.c_ulong()
CHK( dll.DAQmxCreateTask('', ctypes.byref(self._ao_task)) )
CHK( dll.DAQmxCreateTask('', ctypes.byref(self._co_task)) )
CHK( dll.DAQmxCreateAOVoltageChan(self._ao_task,
self._analog_channels,
'',
ctypes.c_double(self._voltage_range[0]),
ctypes.c_double(self._voltage_range[1]),
DAQmx_Val_Volts,
'') )
CHK( dll.DAQmxCreateCOPulseChanFreq( self._co_task,
self._output_counter, '',
DAQmx_Val_Hz, DAQmx_Val_Low, ctypes.c_double(0),
ctypes.c_double(self._seconds_per_point),
ctypes.c_double(self._duty_cycle) ) )
def set_timing(self, seconds_per_point, duty_cycle=0.5):
if seconds_per_point == self._seconds_per_point and duty_cycle == self._duty_cycle:
return
CHK( dll.DAQmxSetCOPulseFreq( self._co_task, self._output_counter, ctypes.c_double(1./seconds_per_point) ) )
CHK( dll.DAQmxSetCOPulseDutyCyc( self._co_task, self._output_counter, ctypes.c_double(duty_cycle) ) )
self._seconds_per_point = seconds_per_point
self._duty_cycle = duty_cycle
def set_length(self, N):
if self._length == N:
return
if N == 1:
CHK( dll.DAQmxSetSampTimingType( self._ao_task, DAQmx_Val_OnDemand) )
else:
CHK( dll.DAQmxSetSampTimingType( self._ao_task, DAQmx_Val_SampClk) )
CHK( dll.DAQmxCfgSampClkTiming( self._ao_task,
self._output_counter+'InternalOutput',
ctypes.c_double(1./self._seconds_per_point),
DAQmx_Val_Rising,
DAQmx_Val_FiniteSamps,
ctypes.c_ulonglong(N)) )
CHK( dll.DAQmxCfgImplicitTiming( self._co_task, DAQmx_Val_FiniteSamps, ctypes.c_ulonglong(N+1)) )
self._length = N
def set_output(self, data):
"""If len(data)==1, output one point. Else output sequence of points.
The shape of data is (n_channels,n_points)."""
if data.ndim == 1:
N = 1
else:
N = data.shape[1]
self.set_length(N)
if N == 1:
CHK(
dll.DAQmxWriteAnalogF64(
self._ao_task, ctypes.c_long(1), 1,
ctypes.c_double(self._transfer_timeout),
DAQmx_Val_GroupByChannel, data.ctypes.data,
ctypes.byref(self._n_written), None))
else:
CHK(
dll.DAQmxWriteAnalogF64(
self._ao_task, ctypes.c_long(N), 0,
ctypes.c_double(self._transfer_timeout),
DAQmx_Val_GroupByChannel, data.ctypes.data,
ctypes.byref(self._n_written), None))
CHK(dll.DAQmxStartTask(self._ao_task))
CHK(dll.DAQmxStartTask(self._co_task))
CHK(
dll.DAQmxWaitUntilTaskDone(
self._ao_task,
ctypes.c_double(4 * (N + 1) * self._seconds_per_point)))
time.sleep(4. * self._seconds_per_point)
CHK(dll.DAQmxStopTask(self._co_task))
CHK(dll.DAQmxStopTask(self._ao_task))
return self._n_written
def __del__(self):
CHK( dll.DAQmxClearTask(self._ao_task) )
CHK( dll.DAQmxClearTask(self._co_task) )