NI DAQMX Channel Attributes Digital Input

Channel Attributes - Digital Input

See how to get and set attributes.

• DAQmx_DI_InvertLines
• DAQmx_DI_NumLines
• Digital Filter
  • DAQmx_DI_DigFltr_Enable
  • DAQmx_DI_DigFltr_MinPulseWidth
  • DAQmx_DI_DigFltr_EnableBusMode
  • Timebase
    • DAQmx_DI_DigFltr_TimebaseSrc
    • DAQmx_DI_DigFltr_TimebaseRate
• Digital Synchronization
  • DAQmx_DI_DigSync_Enable
• DAQmx_DI_Tristate
• DAQmx_DI_LogicFamily
• General Properties
  • Advanced
    • Data Transfer And Memory
      • DAQmx_DI_DataXferMech
      • DAQmx_DI_DataXferReqCond
      • DAQmx_DI_UsbXferReqSize
      • DAQmx_DI_UsbXferReqCount
      • DAQmx_DI_MemMapEnable
    • DAQmx_DI_AcquireOn

DAQmx_DI_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_DI_NumLines

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

You can get this attribute using:   DAQmxGetChanAttribute

Digital Input Digital Filter

DAQmx_DI_DigFltr_Enable

Data Type:	bool32
Description:	Specifies whether to enable the digital filter for the line(s) or port(s). You can enable the filter on a line-by-line basis. You do not have to enable the filter for all lines in a channel.

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

DAQmx_DI_DigFltr_MinPulseWidth

Data Type:	float64
Description:	Specifies in seconds the minimum pulse width the filter recognizes as a valid high or low state transition.

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

DAQmx_DI_DigFltr_EnableBusMode

Data Type:

bool32

Description:

Specifies whether to enable bus mode for digital filtering. If you set this property to TRUE, NI-DAQmx treats all lines that use common filtering settings as a bus. If any line in the bus has jitter, all lines in the bus hold state until the entire bus stabilizes, or until 2 times the minimum pulse width elapses. If you set this property to FALSE, NI-DAQmx filters all lines individually. Jitter in one line does not affect other lines.

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

Digital Input Timebase

DAQmx_DI_DigFltr_TimebaseSrc

Data Type:	char*
Description:	Specifies the terminal of the signal to use as the timebase of the digital filter.

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

DAQmx_DI_DigFltr_TimebaseRate

Data Type:	float64
Description:	Specifies in hertz the rate of the digital filter timebase. NI-DAQmx uses this value to compute settings for the filter.

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

Digital Input Digital Synchronization

DAQmx_DI_DigSync_Enable

Data Type:	bool32
Description:	Specifies whether to synchronize recognition of transitions in the signal to the internal timebase of the device.

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

DAQmx_DI_Tristate

Data Type:	bool32
Description:	Specifies whether to tristate the lines in the channel. If you set this property to TRUE, NI-DAQmx tristates the lines in the channel. If you set this property to FALSE, NI-DAQmx does not modify the configuration of the lines even if the lines were previously tristated. Set this property to FALSE to read lines in other tasks or to read output-only lines.

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

DAQmx_DI_LogicFamily

Data Type:	int32
Description:	Specifies the logic family to use for acquisition. 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

Digital Input General Properties

Digital Input Advanced

Digital Input Data Transfer And Memory

DAQmx_DI_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_DI_DataXferReqCond

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

Valid values

DAQmx_Val_OnBrdMemMoreThanHalfFull	10237	Transfer data from the device when more than half of the onboard memory of the device fills.
DAQmx_Val_OnBrdMemNotEmpty	10241	Transfer data from the device when there is data in the onboard memory.
DAQmx_Val_OnbrdMemCustomThreshold	12577	Transfer data from the device when the number of samples specified with DAQmx_AI_DataXferCustomThreshold are in the device FIFO.
DAQmx_Val_WhenAcqComplete	12546	Transfer data when the acquisition is complete.

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

DAQmx_DI_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_DI_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_DI_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_DI_AcquireOn

Data Type:	int32
Description:	Specifies on which edge of the sample clock to acquire 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