Digital Input and Output

Acquire and generate digital data with data acquisition hardware

Digital subsystems perform read and write operations to transfer and receive digital or logical values in bits via digital lines. Data Acquisition Toolbox™ provides a DataAcquisition interface to perform these operations in clocked and non-clocked systems.

Add digital subsystem channels, known as digital lines, to your DataAcquisition interface object using the addinput, addoutput, or addbidirectional functions.

Input only channel — Acquire digital data using the read operation.
Output only channel — Generate digital data using the write operation.
Bidirectional channel — Acquire or generate digital data by modifying the channel direction. You can set the direction to either Input or Output, but not both at the same time. By default, the direction is Input.

Before you use digital channels, see Hardware Discovery and Setup.

Functions

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Channel Configuration

`addinput`	Add input channel to device interface
`addoutput`	Add output channel to device interface
`addbidirectional`	Add digital bidirectional channel to device interface
`removechannel`	Remove channel from device interface

Reading and Writing Data

`read`	Read data acquired by hardware
`write`	Write output scans to hardware channels
`readwrite`	Simultaneously read and write device channel data
`start`	Start `DataAcquisition` background operation
`stop`	Stop background operation
`preload`	Queue scan data for device output
`flush`	Flush DataAcquisition input and output buffers

Data Format Conversion

`decimalToBinaryVector`	Convert decimal value to binary vector
`binaryVectorToDecimal`	Convert binary vector value to decimal value
`hexToBinaryVector`	Convert hexadecimal value to binary vector
`binaryVectorToHex`	Convert binary vector value to hexadecimal

Topics

Digital Subsystem

Digital Clocked Operations
Acquire or generate clocked signals at a specified scan rate.
Access Digital Subsystem Information
Find line and port information of a digital subsystem.

Digital Data Acquisition

Acquire Non-Clocked Digital Data
Acquire a single scan of digital data from two channels of an NI device.
Acquire Digital Data Using a Shared Clock
Share the clock of the analog subsystem on your device for the digital acquisition.
Acquire Digital Data Using an External Clock
Acquire digital data in the foreground using an external scan clock.
Acquire Digital Data Using a Counter Output Channel as External Clock
Acquire digital data using a counter output channel to generate clock pulses.
Acquire Digital Data in Hexadecimal Values
Acquire digital data using four channels on an NI 6255.

Digital Data Generation

Generate Non-Clocked Digital Data
Write data to two lines on an NI 6255.
Generate Digital Data Using a Shared Clock
Share the clock of the analog subsystem and write data to a digital output channel on an NI USB-6351.
Generate Digital Output Using Decimal Data Across Multiple Lines
Convert decimal data and output to two lines on an NI 6255.
Generate Signals on Both Analog and Digital Channels
Generate signals when the DataAcquisition object contains both analog and digital channels.

Bidirectional System

Generate and Acquire Data on Bidirectional Channels
Use a bidirectional channel and read and write data using the same two lines on an NI 6255.

Featured Examples

Control Stepper Motor Using Digital Outputs

Control a stepper motor using digital output ports.

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Communicate with I2C Devices and Analyze Bus Signals Using Digital IO

Communicate with instruments and devices at the protocol layer as well as the physical layer.

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