NI DAQMX Channel Attributes Analog Output

Channel Attributes - Analog Output

See how to get and set attributes.

• DAQmx_AO_Max
• DAQmx_AO_Min
• DAQmx_AO_CustomScaleName
• DAQmx_AO_OutputType
• Voltage
  • DAQmx_AO_Voltage_Units
  • DAQmx_AO_Voltage_CurrentLimit
• Current
  • DAQmx_AO_Current_Units
• Function Generation
  • DAQmx_AO_FuncGen_Type
  • DAQmx_AO_FuncGen_Freq
  • DAQmx_AO_FuncGen_Amplitude
  • DAQmx_AO_FuncGen_Offset
  • Square
    • DAQmx_AO_FuncGen_Square_DutyCycle
  • Modulation
    • DAQmx_AO_FuncGen_ModulationType
    • DAQmx_AO_FuncGen_FMDeviation
• General Properties
  • Output Configuration
    • DAQmx_AO_OutputImpedance
    • DAQmx_AO_LoadImpedance
    • DAQmx_AO_IdleOutputBehavior
    • DAQmx_AO_TermCfg
    • DAQmx_AO_Common_Mode_Offset
  • Dac
    • DAQmx_AO_ResolutionUnits
    • DAQmx_AO_Resolution
    • Range
      • DAQmx_AO_DAC_Rng_High
      • DAQmx_AO_DAC_Rng_Low
    • Reference Voltage
      • DAQmx_AO_DAC_Ref_ConnToGnd
      • DAQmx_AO_DAC_Ref_AllowConnToGnd
      • DAQmx_AO_DAC_Ref_Src
      • DAQmx_AO_DAC_Ref_ExtSrc
      • DAQmx_AO_DAC_Ref_Val
    • Offset Voltage
      • DAQmx_AO_DAC_Offset_Src
      • DAQmx_AO_DAC_Offset_ExtSrc
      • DAQmx_AO_DAC_Offset_Val
    • DAQmx_AO_ReglitchEnable
  • Filter
    • DAQmx_AO_FilterDelay
    • DAQmx_AO_FilterDelayUnits
    • DAQmx_AO_FilterDelayAdjustment
  • Advanced
    • Gain
      • DAQmx_AO_Gain
    • Data Transfer And Memory
      • DAQmx_AO_UseOnlyOnBrdMem
      • DAQmx_AO_DataXferMech
      • DAQmx_AO_DataXferReqCond
      • DAQmx_AO_UsbXferReqSize
      • DAQmx_AO_UsbXferReqCount
      • DAQmx_AO_MemMapEnable
    • Device Scaling Coefficients
      • DAQmx_AO_DevScalingCoeff
    • DAQmx_AO_EnhancedImageRejectionEnable

DAQmx_AO_Max

Data Type:	float64
Description:	Specifies the maximum value you expect to generate. The value is in the units you specify with a units property. If you try to write a value larger than the maximum value, NI-DAQmx generates an error. NI-DAQmx might coerce this value to a smaller value if other task settings restrict the device from generating the desired maximum.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_Min

Data Type:	float64
Description:	Specifies the minimum value you expect to generate. The value is in the units you specify with a units property. If you try to write a value smaller than the minimum value, NI-DAQmx generates an error. NI-DAQmx might coerce this value to a larger value if other task settings restrict the device from generating the desired minimum.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_CustomScaleName

Data Type:	char*
Description:	Specifies the name of a custom scale for the channel.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_OutputType

Data Type:	int32
Description:	Indicates whether the channel generates voltage, current, or a waveform.
Restrictions:	Not Settable

Valid values

DAQmx_Val_Voltage	10322	Voltage generation.
DAQmx_Val_Current	10134	Current generation.
DAQmx_Val_FuncGen	14750	Function generation.

You can get this attribute using:   DAQmxGetChanAttribute

Output Voltage

DAQmx_AO_Voltage_Units

Data Type:	int32
Description:	Specifies in what units to generate voltage on the channel. Write data to the channel in the units you select.

Valid values

DAQmx_Val_Volts	10348	Volts.
DAQmx_Val_FromCustomScale	10065	Units a custom scale specifies. If you select this value, you must specify a custom scale name.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_Voltage_CurrentLimit

Data Type:	float64
Description:	Specifies the current limit, in amperes, for the voltage channel.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

Output Current

DAQmx_AO_Current_Units

Data Type:	int32
Description:	Specifies in what units to generate current on the channel. Write data to the channel in the units you select.

Valid values

DAQmx_Val_Amps	10342	Amperes.
DAQmx_Val_FromCustomScale	10065	Units a custom scale specifies. If you select this value, you must specify a custom scale name.
DAQmx_Val_FromTEDS	12516	Units defined by TEDS information associated with the channel.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

Function Generation

DAQmx_AO_FuncGen_Type

Data Type:	int32
Description:	Specifies the kind of the waveform to generate.

Valid values

DAQmx_Val_Sine	14751	Sine wave.
DAQmx_Val_Triangle	14752	Triangle wave.
DAQmx_Val_Square	14753	Square wave.
DAQmx_Val_Sawtooth	14754	Sawtooth wave.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_FuncGen_Freq

Data Type:	float64
Description:	Specifies the frequency of the waveform to generate in hertz.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_FuncGen_Amplitude

Data Type:	float64
Description:	Specifies the zero-to-peak amplitude of the waveform to generate in volts. Zero and negative values are valid.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_FuncGen_Offset

Data Type:	float64
Description:	Specifies the voltage offset of the waveform to generate.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

Square

DAQmx_AO_FuncGen_Square_DutyCycle

Data Type:	float64
Description:	Specifies the square wave duty cycle of the waveform to generate.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

Modulation

DAQmx_AO_FuncGen_ModulationType

Data Type:	int32
Description:	Specifies if the device generates a modulated version of the waveform using the original waveform as a carrier and input from an external terminal as the signal.

Valid values

DAQmx_Val_AM	14756	Amplitude modulation.
DAQmx_Val_FM	14757	Frequency modulation.
DAQmx_Val_None	10230	No modulation.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_FuncGen_FMDeviation

Data Type:	float64
Description:	Specifies the FM deviation in hertz per volt when DAQmx_AO_FuncGen_ModulationType is DAQmx_Val_FM.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

Analog Output General Properties

Output Configuration

DAQmx_AO_OutputImpedance

Data Type:	float64
Description:	Specifies in ohms the impedance of the analog output stage of the device.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_LoadImpedance

Data Type:	float64
Description:	Specifies in ohms the load impedance connected to the analog output channel.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_IdleOutputBehavior

Data Type:	int32
Description:	Specifies the state of the channel when no generation is in progress.

Valid values

DAQmx_Val_ZeroVolts	12526	Generate 0 V.
DAQmx_Val_HighImpedance	12527	Set the channel to high-impedance, effectively disconnecting the analog output circuitry from the I/O connector.
DAQmx_Val_MaintainExistingValue	12528	Continue generating the current value.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_TermCfg

Data Type:	int32
Description:	Specifies the terminal configuration of the channel.

Valid values

DAQmx_Val_RSE	10083	Referenced Single-Ended.
DAQmx_Val_Diff	10106	Differential.
DAQmx_Val_PseudoDiff	12529	Pseudodifferential.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_Common_Mode_Offset

Data Type:	float64
Description:	Specifies the common-mode offset of the AO channel. Use the property only when Terminal Configuration is set to Differential.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

Dac

DAQmx_AO_ResolutionUnits

Data Type:	int32
Description:	Specifies the units of DAQmx_AO_Resolution.

Valid values

DAQmx_Val_Bits	10109	Bits.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_Resolution

Data Type:	float64
Description:	Indicates the resolution of the digital-to-analog converter of the channel. This value is in the units you specify with DAQmx_AO_ResolutionUnits.
Restrictions:	Not Settable

You can get this attribute using:   DAQmxGetChanAttribute

Range

DAQmx_AO_DAC_Rng_High

Data Type:	float64
Description:	Specifies the upper limit of the output range of the device. This value is in the native units of the device. On E Series devices, for example, the native units is volts.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_DAC_Rng_Low

Data Type:	float64
Description:	Specifies the lower limit of the output range of the device. This value is in the native units of the device. On E Series devices, for example, the native units is volts.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

Reference Voltage

DAQmx_AO_DAC_Ref_ConnToGnd

Data Type:

bool32

Description:

Specifies whether to ground the internal DAC reference. Grounding the internal DAC reference has the effect of grounding all analog output channels and stopping waveform generation across all analog output channels regardless of whether the channels belong to the current task. You can ground the internal DAC reference only when DAQmx_AO_DAC_Ref_Src is DAQmx_Val_Internal and DAQmx_AO_DAC_Ref_AllowConnToGnd is TRUE.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_DAC_Ref_AllowConnToGnd

Data Type:	bool32
Description:	Specifies whether to allow grounding the internal DAC reference at run time. You must set this property to TRUE and set DAQmx_AO_DAC_Ref_Src to DAQmx_Val_Internal before you can set DAQmx_AO_DAC_Ref_ConnToGnd to TRUE.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_DAC_Ref_Src

Data Type:	int32
Description:	Specifies the source of the DAC reference voltage. The value of this voltage source determines the full-scale value of the DAC.

Valid values

DAQmx_Val_Internal	10200	Internal to the device.
DAQmx_Val_External	10167	External to the device.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_DAC_Ref_ExtSrc

Data Type:	char*
Description:	Specifies the source of the DAC reference voltage if DAQmx_AO_DAC_Ref_Src is DAQmx_Val_External. The valid sources for this signal vary by device.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_DAC_Ref_Val

Data Type:	float64
Description:	Specifies in volts the value of the DAC reference voltage. This voltage determines the full-scale range of the DAC. Smaller reference voltages result in smaller ranges, but increased resolution.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

Offset Voltage

DAQmx_AO_DAC_Offset_Src

Data Type:	int32
Description:	Specifies the source of the DAC offset voltage. The value of this voltage source determines the full-scale value of the DAC.

Valid values

DAQmx_Val_Internal	10200	Internal to the device.
DAQmx_Val_External	10167	External to the device.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_DAC_Offset_ExtSrc

Data Type:	char*
Description:	Specifies the source of the DAC offset voltage if DAQmx_AO_DAC_Offset_Src is DAQmx_Val_External. The valid sources for this signal vary by device.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_DAC_Offset_Val

Data Type:	float64
Description:	Specifies in volts the value of the DAC offset voltage. To achieve best accuracy, the DAC offset value should be hand calibrated.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_ReglitchEnable

Data Type:

bool32

Description:

Specifies whether to enable reglitching. The output of a DAC normally glitches whenever the DAC is updated with a new value. The amount of glitching differs from code to code and is generally largest at major code transitions. Reglitching generates uniform glitch energy at each code transition and provides for more uniform glitches. Uniform glitch energy makes it easier to filter out the noise introduced from glitching during spectrum analysis.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

Output Filter

DAQmx_AO_FilterDelay

Data Type:	float64
Description:	Specifies the amount of time between when the sample is written by the host device and when the sample is output by the DAC. This value is in the units you specify with DAQmx_AO_FilterDelayUnits.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_FilterDelayUnits

Data Type:	int32
Description:	Specifies the units of DAQmx_AO_FilterDelay and DAQmx_AO_FilterDelayAdjustment.

Valid values

DAQmx_Val_Seconds	10364	Seconds.
DAQmx_Val_SampleClkPeriods	10286	Sample Clock Periods.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_FilterDelayAdjustment

Data Type:	float64
Description:	Specifies an additional amount of time to wait between when the sample is written by the host device and when the sample is output by the DAC. This delay adjustment is in addition to the value indicated by DAQmx_AO_FilterDelay. This delay adjustment is in the units you specify with DAQmx_AO_FilterDelayUnits.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

Output Advanced

Gain

DAQmx_AO_Gain

Data Type:	float64
Description:	Specifies in decibels the gain factor to apply to the channel.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

Analog Output Data Transfer And Memory

DAQmx_AO_UseOnlyOnBrdMem

Data Type:	bool32
Description:	Specifies whether to write samples directly to the onboard memory of the device, bypassing the memory buffer. Generally, you cannot update onboard memory directly after you start the task. Onboard memory includes data FIFOs.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_DataXferMech

Data Type:	int32
Description:	Specifies the data transfer mode for the device.

Valid values

DAQmx_Val_DMA	10054	Direct Memory Access. Data transfers take place independently from the application.
DAQmx_Val_Interrupts	10204	Data transfers take place independently from the application. Using interrupts increases CPU usage because the CPU must service interrupt requests. Typically, you should use interrupts if the device is out of DMA channels.
DAQmx_Val_ProgrammedIO	10264	Data transfers take place when you call an NI-DAQmx Read function or an NI-DAQmx Write function.
DAQmx_Val_USBbulk	12590	Data transfers take place independently from the application using a USB bulk pipe.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_DataXferReqCond

Data Type:	int32
Description:	Specifies under what condition to transfer data from the buffer to the onboard memory of the device.

Valid values

DAQmx_Val_OnBrdMemEmpty	10235	Transfer data to the device only when there is no data in the onboard memory of the device.
DAQmx_Val_OnBrdMemHalfFullOrLess	10239	Transfer data to the device any time the onboard memory is less than half full.
DAQmx_Val_OnBrdMemNotFull	10242	Transfer data to the device any time the onboard memory of the device is not full.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_UsbXferReqSize

Data Type:	uInt32
Description:	Specifies the maximum size of a USB transfer request in bytes. Modify this value to affect performance under different combinations of operating system and device.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_UsbXferReqCount

Data Type:	uInt32
Description:	Specifies the maximum number of simultaneous USB transfers used to stream data. Modify this value to affect performance under different combinations of operating system and device.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

DAQmx_AO_MemMapEnable

Data Type:

bool32

Description:

Specifies for NI-DAQmx to map hardware registers to the memory space of the application, if possible. Normally, NI-DAQmx maps hardware registers to memory accessible only to the kernel. Mapping the registers to the memory space of the application increases performance. However, if the application accesses the memory space mapped to the registers, it can adversely affect the operation of the device and possibly result in a system crash.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute

Output Device Scaling Coefficients

DAQmx_AO_DevScalingCoeff

Data Type:	float64*
Description:	Indicates the coefficients of a linear equation that NI-DAQmx uses to scale values from a voltage to the native format of the device. Each element of the array corresponds to a term of the equation. The first element of the array corresponds to the y-intercept, and the second element corresponds to the slope. Scaling coefficients do not account for any custom scales that may be applied to the channel.
Restrictions:	Not Settable

You can get this attribute using:   DAQmxGetChanAttribute

DAQmx_AO_EnhancedImageRejectionEnable

Data Type:	bool32
Description:	Specifies whether to enable the DAC interpolation filter. Disable the interpolation filter to improve DAC signal-to-noise ratio at the expense of degraded image rejection.

You can get/set/reset this attribute using:   DAQmxGetChanAttribute   DAQmxSetChanAttribute   DAQmxResetChanAttribute