NI DAQMX Channel Attributes Digital Output

Channel Attributes - Digital Output

See how to get and set attributes.

• DAQmx_DO_OutputDriveType
• DAQmx_DO_InvertLines
• DAQmx_DO_NumLines
• DAQmx_DO_Tristate
• Line States
  • DAQmx_DO_LineStates_StartState
  • DAQmx_DO_LineStates_PausedState
  • DAQmx_DO_LineStates_DoneState
• DAQmx_DO_LogicFamily
• Overcurrent
  • DAQmx_DO_Overcurrent_Limit
  • DAQmx_DO_Overcurrent_AutoReenable
  • DAQmx_DO_Overcurrent_ReenablePeriod
• General Properties
  • Advanced
    • Data Transfer And Memory
      • DAQmx_DO_UseOnlyOnBrdMem
      • DAQmx_DO_DataXferMech
      • DAQmx_DO_DataXferReqCond
      • DAQmx_DO_UsbXferReqSize
      • DAQmx_DO_UsbXferReqCount
      • DAQmx_DO_MemMapEnable
    • DAQmx_DO_GenerateOn

DAQmx_DO_OutputDriveType

Data Type:	int32
Description:	Specifies the drive type for digital output channels.

Valid values

DAQmx_Val_ActiveDrive	12573	Drive the output pin to approximately 0 V for logic low and +3.3 V or +5 V, depending on the device, for logic high.
DAQmx_Val_OpenCollector	12574	Drive the output pin to 0 V for logic low. For logic high, the output driver assumes a high-impedance state and does not drive a voltage.

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

DAQmx_DO_InvertLines

Data Type:	bool32
Description:	Specifies whether to invert the lines in the channel. If you set this property to TRUE, the lines are at high logic when off and at low logic when on.

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

DAQmx_DO_NumLines

Data Type:	uInt32
Description:	Indicates the number of digital lines in the channel.
Restrictions:	Not Settable

You can get this attribute using:   DAQmxGetChanAttribute

DAQmx_DO_Tristate

Data Type:	bool32
Description:	Specifies whether to stop driving the channel and set it to a high-impedance state. You must commit the task for this setting to take effect.

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

Line States

DAQmx_DO_LineStates_StartState

Data Type:	int32
Description:	Specifies the state of the lines in a digital output task when the task starts.

Valid values

DAQmx_Val_High	10192	Logic high.
DAQmx_Val_Low	10214	Logic low.
DAQmx_Val_Tristate	10310	High-impedance state. You can select this state only on devices with bidirectional lines. You cannot select this state for dedicated digital output lines. On some devices, you can select this value only for entire ports.
DAQmx_Val_NoChange	10160	Do not change the state of the lines. On some devices, you can select this value only for entire ports.

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

DAQmx_DO_LineStates_PausedState

Data Type:	int32
Description:	Specifies the state of the lines in a digital output task when the task pauses.

Valid values

DAQmx_Val_High	10192	Logic high.
DAQmx_Val_Low	10214	Logic low.
DAQmx_Val_Tristate	10310	High-impedance state. You can select this state only on devices with bidirectional lines. You cannot select this state for dedicated digital output lines. On some devices, you can select this value only for entire ports.
DAQmx_Val_NoChange	10160	Do not change the state of the lines. On some devices, you can select this value only for entire ports.

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

DAQmx_DO_LineStates_DoneState

Data Type:	int32
Description:	Specifies the state of the lines in a digital output task when the task completes execution.

Valid values

DAQmx_Val_High	10192	Logic high.
DAQmx_Val_Low	10214	Logic low.
DAQmx_Val_Tristate	10310	High-impedance state. You can select this state only on devices with bidirectional lines. You cannot select this state for dedicated digital output lines. On some devices, you can select this value only for entire ports.
DAQmx_Val_NoChange	10160	Do not change the state of the lines. On some devices, you can select this value only for entire ports.

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

DAQmx_DO_LogicFamily

Data Type:	int32
Description:	Specifies the logic family to use for generation. A logic family corresponds to voltage thresholds that are compatible with a group of voltage standards. Refer to the device documentation for information on the logic high and logic low voltages for these logic families.

Valid values

DAQmx_Val_2point5V	14620	Compatible with 2.5 V CMOS signals.
DAQmx_Val_3point3V	14621	Compatible with LVTTL signals.
DAQmx_Val_5V	14619	Compatible with TTL and 5 V CMOS signals.

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

Overcurrent

DAQmx_DO_Overcurrent_Limit

Data Type:	float64
Description:	Specifies the current threshold in Amperes for the channel. A value of 0 means the channel observes no limit. Devices can monitor only a finite number of current thresholds simultaneously. If you attempt to monitor additional thresholds, NI-DAQmx returns an error.

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

DAQmx_DO_Overcurrent_AutoReenable

Data Type:	bool32
Description:	Specifies whether to automatically reenable channels after they no longer exceed the current limit specified by DAQmx_DO_Overcurrent_Limit.

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

DAQmx_DO_Overcurrent_ReenablePeriod

Data Type:	float64
Description:	Specifies the delay in seconds between the time a channel no longer exceeds the current limit and the reactivation of that channel, if DAQmx_DO_Overcurrent_AutoReenable is TRUE.

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

Digital Output General Properties

Digital Output Advanced

Digital Output Data Transfer And Memory

DAQmx_DO_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 after you start the task. Onboard memory includes data FIFOs.

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

DAQmx_DO_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_DO_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_DO_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_DO_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_DO_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

DAQmx_DO_GenerateOn

Data Type:	int32
Description:	Specifies on which edge of the sample clock to generate samples.

Valid values

DAQmx_Val_SampClkActiveEdge	14617	Active edges.
DAQmx_Val_SampClkInactiveEdge	14618	Inactive edges.

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