DataAcquisition

Interface to data acquisition device

Description

The DataAcquisition object provides access to the devices of a specified vendor.

Creation

Use the daq function to create a DataAcquisition object.

Properties

AutoSyncDSA — Automatically Synchronize DSA devices

false (default) | true

Automatically Synchronize DSA devices, specified as a logical true or false. Use this property to enable or disable automatic synchronization between DSA (PXI or PCI) devices in the same DataAcquisition. By default automatic synchronization capability is disabled.

Example: true

Data Types: logical

Channels — Device channels

array of channel objects

This property is read-only.

Device channels, returned as an array of channel objects. Create channels with the functions addinput, addoutput, and addbidirectional.

Example: addinput(d,…)

Clocks — Device clock connections

array of clock objects

This property is read-only.

Device clock connections, returned as an array of clock objects. Create clocks with the addclock function.

Example: addclock(d,…)

DigitalTriggers — Device digital trigger connections

array of DigitalTrigger objects

This property is read-only.

Device digital trigger connections, returned as an array of DigitalTrigger objects. Use the addtigger function to add digital triggers to the DataAcquisition.

Example: addtrigger(d,…)

DigitalTriggerTimeout — Time allowed for occurrence of digital trigger

10 (default) | numeric | duration

Time allowed for occurrence of digital trigger, specified as a numeric value in seconds or a duration.

Example: 30

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | duration

ErrorOccurredFcn — Callback function to call when error occurs

function handle

Callback function to call when error occurs, specified as a function handle.

Example: @mycleanup

Data Types: function_handle

NumDigitalTriggerRemaining — Number of digital triggers remaining in run

1 (default) | numeric

This property is read-only.

Number of digital triggers remaining in run, returned as a double.

Example: 1

Data Types: double

NumDigitalTriggersPerRun — Number of digital triggers per DataAcquisition run

numeric

Number of digital triggers per DataAcquisition run, returned as a double.

Example: 2

Data Types: double

NumScansAvailable — Number of data scans acquired and available for reading

numeric

This property is read-only.

Number of data scans available for reading, returned as a double. These scans have been acquired by the device input channels.

Example: 1000

Data Types: uint64

NumScansOutputByHardware — Number of scans generated as device output

numeric

This property is read-only.

Number of scans generated as device output, returned as a double.

Example: 1024

Data Types: uint64

NumScansQueued — Number of scans prepared for device output

numeric

This property is read-only.

Number of scans queued to the output channels

Example: 4000

Data Types: uint64

Rate — Data scan rate

numeric

Data scan rate, specified as a numeric value of samples per second.

Example: 44100

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

RateLimit — Lower and upper scan rate limits

array of doubles

This property is read-only.

Lower and upper scan rate limits, returned as a 1-by-2 vector of doubles indicating minimum and maximum allowed scan rates in samples per second. The scan rate limits depend on the hardware and its configurations. In devices that multiplex channels to a converter, the rate limit is impacted by the number of channels you use. For more information, see Sampling.

Example: [8000 192000]

Data Types: double

Running — DataAcquisition running indication

true | false

This property is read-only.

DataAcquisition running indication, returned as true or false.

Example: true

Data Types: logical

ScansAvailableFcn — Callback function when scans are available

function handle

Callback function to execute when scans are available from the input channels, specified as a function handle

Example: @read

Data Types: function_handle

ScansAvailableFcnCount — Number of acquired scans to trigger ScansAvailableFcn

numeric

Number of acquired scans to trigger ScansAvailableFcn, specified as a numeric value. The function handle specified in ScansAvailableFcn executes every time ScansAvailableFcnCount scans are acquired from the input channels.

Example: 8000

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64

ScansRequiredFcn — Callback function when output scan data is required

function handle

Callback function to execute when scan data is required for device output channels. specified as a function handle.

Example: @write

Data Types: function_handle

ScansRequiredFcnCount — Number of scans to trigger ScansRequiredFcn

"auto" (default) | numeric

Number of queued scans to trigger ScansRequiredFcn, specified as a numeric value or "auto". The function handle specified in ScansRequiredFcn executes when NumScansQueued drops below the value specified in this property. If this is set to "auto", the value resets to a default.

Example: 2000

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | char | string

UserData — Custom data

any data

Custom data, specified as any MATLAB^® data type and format.

Example: datetime('now')

Data Types: single | double | int8 | int16 | int32 | int64 | uint8 | uint16 | uint32 | uint64 | logical | char | string | struct | table | cell | function_handle | categorical | datetime | duration | calendarDuration | fi

Vendor — Data acquisition hardware vendor information

vendor object

This property is read-only.

Data acquisition hardware vendor information, returned as a vendor object with the following properties:

ID
FullName
AdaptorVersion
DriverVersion
IsOperational

This object is the same as the corresponding vendor object returned by the daqvendorlist function.

WaitingForDigitalTrigger — Digital trigger waiting indication

false (default) | true

This property is read-only.

Digital trigger waiting indication, returned as a logical.

Example: true

Data Types: logical

Object Functions

addinput	Add input channel to device interface
read	Read data acquired by hardware
readwrite	Simultaneously read and write device channel data
start	Start DataAcquisition background operation
stop	Stop background operation
removechannel	Remove channel from device interface
flush	Flush DataAcquisition input and output buffers
write	Write output scans to hardware channels
preload	Queue scan data for device output
addoutput	Add output channel to device interface
addbidirectional	Add digital bidirectional channel to device interface
resetcounters	Reset hardware scan count for all counter inputs
addclock	Add clock connection to device interface
removeclock	Remove clock from device interface
addtrigger	Add trigger connection to device interface
removetrigger	Remove trigger from device interface

Examples

Create a DataAcquisition

Create and configure a DataAcquisition object for interfacing with National Instruments^® devices.

d = daq("ni")
d.Rate = 20000;