API

Instrument

The NIDAQmxInstrument class is the primary method through which most users will acquire hardware.

class daqmx.NIDAQmxInstrument(device_name: str = None, serial_number: (<class 'str'>, <class 'int'>) = None, model_number: str = None, loglevel=20)

This class will create the tasks and coordinate with the hardware in order to achieve a particular end on an input or output of the DAQ module.

The methods within this object utilize the concepts found in the NI-DAQmx Help menu, such as channels and tasks.

Parameters

  • device_name – the device name, often formatted like Dev3

  • serial_number – the serial number as a hexadecimal value (this is usually what is printed on the label)

  • model_number – the model number as printed on the label

property sn

Returns the device serial number

Returns

the device serial number

property model

Returns the device model number

Returns

the device model number

property outputs

Returns a list of outputs associated with the device.

Returns

a list of outputs associated with the device.

property inputs

Returns a list of inputs associated with the device

Returns

a list of inputs associated with the device

Port

The Port class is the class which implements port writes and reads. It may be used directly or through the instrument.

class daqmx.Port(device: str, port: str)

Represents the port object as defined by DAQmx.

Parameters

  • device – the device string as defined by DAQmx (i.e. ‘Dev3’)

  • port – the port name as defined by DAQmx (i.e. ‘port2’)

property lines

Lists all of the lines attached to the port

Returns

a list of line names

Analog Input

The AnalogInput class is the class which implements most of the analog input functionality. It may be used directly or through the instrument.

class daqmx.AnalogInput(device: str, analog_input: str = None, sample_count: int = 1000, rate: (<class 'int'>, <class 'float'>) = 1000.0, max_voltage: (<class 'int'>, <class 'float'>) = 5.0, min_voltage: (<class 'int'>, <class 'float'>) = 0.0, mode: str = 'differential', timeout: (<class 'int'>, <class 'float'>) = None)

Represents an analog input on the DAQmx device.

Parameters

  • device – the device string assigned by DAQmx (i.e. ‘Dev3)

  • analog_input – the analog input name assigned by DAQmx (i.e. “ao0”)

  • sample_count – the number of samples to take

  • rate – the frequency at which to sample the input

  • max_voltage – the maximum expected voltage

  • min_voltage – the minimum expected voltage

  • mode – the mode; valid values: differential, pseudo-differential, / singled-ended referenced, singled-ended non-referenced

  • timeout – the time at which an error will occur if no response / from the instrument is received.

property value

Return a single sample of the analog input

Returns

a floating-point value representing the voltage

sample(analog_input: Optional[str] = None)

Return a single sample of the analog input

Returns

a floating-point value representing the voltage

capture(analog_input: str = None, sample_count: int = None, rate: (<class 'int'>, <class 'float'>) = None, max_voltage: (<class 'int'>, <class 'float'>) = None, min_voltage: (<class 'int'>, <class 'float'>) = None, mode: str = None, timeout: (<class 'int'>, <class 'float'>) = None)

Will capture <sample_count> samples at <rate>Hz in the <mode> mode.

Parameters

  • analog_input – the analog input name assigned by DAQmx (i.e. “ao0”)

  • sample_count – the number of samples to take

  • rate – the frequency at which to sample the input

  • max_voltage – the maximum expected voltage

  • min_voltage – the minimum expected voltage

  • mode – the mode; valid values: differential, pseudo-differential, / singled-ended referenced, singled-ended non-referenced

  • timeout – the time at which an error will occur if no response / from the instrument is received.

Returns

a numpy array containing all resulting values

find_dominant_frequency(analog_input: str = None, sample_count: int = None, rate: (<class 'int'>, <class 'float'>) = None, max_voltage: (<class 'int'>, <class 'float'>) = None, min_voltage: (<class 'int'>, <class 'float'>) = None, mode: str = None, timeout: (<class 'int'>, <class 'float'>) = None)

Acquires the fundamental frequency observed within the samples

Parameters

  • analog_input – the NI analog input designation (i.e. ‘ai0’)

  • sample_count – the number of samples to acquired

  • rate – the sample rate in Hz :param max_voltage: the maximum voltage possible

  • min_voltage – the minimum voltage range

  • mode – the voltage mode of operation; choices: ‘differential’, ‘pseudo-differential’, ‘single-ended referenced’, ‘single-ended non-referenced’

  • timeout – the time at which the function should return if this time has elapsed; set to -1 to make infinite (default)

Returns

the frequency found to be at the highest amplitude; this is often the fundamental frequency in many domains