analoginput - Create analog input object

Syntax

Description

AI = analoginput('adaptor') creates the analog input object AI for a sound card having an ID of 0 (adaptor must be winsound). This is the only case where ID is not required.

AI = analoginput('adaptor',ID) creates the analog input object AI for the specified adaptor and for the hardware device with device identifier ID. ID can be specified as an integer or a string.

Note   The Traditional NI-DAQ adaptor will be deprecated in a future version of the toolbox. If you create a Data Acquisition Toolbox™ object for Traditional NI-DAQ adaptor beginning in R2008b, you will receive a warning stating that this adaptor will be removed in a future release. See the supported hardware page at www.mathworks.com/products/daq/supportedio.html for more information.

Tips

Creating Analog Input Objects

• When an analog input object is created, it does not contain any hardware channels. To execute the device object, hardware channels must be added with the addchannel function.

• You can create multiple analog input objects that are associated with a particular analog input subsystem. However, you can typically execute only one object at a time.

• The analog input object exists in the data acquisition engine and in the MATLAB workspace. If you create a copy of the device object, it references the original device object in the engine.

• If ID is a numeric value, then you can specify it as an integer or a string. If ID contains any nonnumeric characters, then you must specify it as a string. (See the National Instruments example below.)

• The Name property is automatically assigned a descriptive name that is produced by concatenating adaptor, ID, and -AI. You can change this name at any time.

Notes   When you create an analog input object, it consumes system resources. To avoid this issue, make sure that you do not create objects in a loop. If you must create objects in a loop, make sure you delete them within the loop.

Hardware Device Identifier

When data acquisition devices are installed, they are assigned a unique number which identifies the device in software. The device identifier is typically assigned automatically and can usually be manually changed using a vendor-supplied device configuration utility. National Instruments refers to this identifier as the device name.

For sound cards, the device identifier is typically not exposed to you through the Microsoft^® Windows^® environment. However, Data Acquisition Toolbox software automatically associates each sound card with an integer ID value. There are two cases to consider:

• If you have one sound card installed, then ID is 0. You are not required to specify ID when creating an analog input object associated with this device.

• If you have multiple sound cards installed, the first one installed has an ID of 0, the second one installed has an ID of 1, and so on. You must specify ID when creating analog input objects associated with devices not having an ID of 0.

There are two ways you can determine the ID for a particular device:

• Type daqhwinfo('adaptor').

• Execute the vendor-supplied device configuration utility.

Input Arguments

adaptor	The hardware driver adaptor name. The supported adaptors are advantech, , mcc, nidaq, and winsound.
ID	The hardware device identifier. ID is optional if the device object is associated with a sound card having an ID of 0.

Output Arguments

AI	The analog input object.

Properties

Basic Setup

SampleRate	Specify per-channel rate at which analog data is converted to digital data, or vice versa
SamplesPerTrigger	Specify number of samples to acquire for each channel group member for each trigger that occurs
TriggerType	Specify type of trigger to execute

Channel Properties

ChannelName	Specify descriptive channel name
HwChannel	Specify hardware channel ID
HwLine	Specify hardware line ID
Index	MATLAB index of hardware channel or line
InputRange	Specify range of analog input subsystem
NativeOffset	Indicate offset to use when converting between native data format and doubles
NativeScaling	Indicate scaling to use when converting between native data format and doubles
Parent	Indicate parent (device object) of channel or line
SensorRange	Specify range of data expected from sensor
Type	Indicate device object type, channel, or line
Units	Specify engineering units label
UnitsRange	Specify range of data as engineering units

Trigger Properties

InitialTriggerTime	Absolute time of first trigger
ManualTriggerHwOn	Specify hardware device starts at manual trigger
TriggerChannel	Specify channel serving as trigger source
TriggerCondition	Specify condition that must be satisfied before trigger executes
TriggerConditionValue	Specify voltage value(s) that must be satisfied before trigger executes
TriggerDelay	Specify delay value for data logging
TriggerDelayUnits	Specify units in which trigger delay data is measured
TriggerFcn	Specify callback function to execute when trigger occurs
TriggerRepeat	Specify number of additional times trigger executes
TriggersExecuted	Indicate number of triggers that execute
TriggerType	Specify type of trigger to execute

Logging Properties

LogFileName	Specify name of disk file information is logged to
Logging	Indicate whether data is being logged to memory or disk file
LoggingMode	Specify destination for acquired data
LogToDiskMode	Specify whether data, events, and hardware information are saved to one or more disk files

Status Properties

Logging	Indicate whether data is being logged to memory or disk file
Running	Indicate whether device object is running
SamplesAcquired	Indicate number of samples acquired per channel
SamplesAvailable	Indicate number of samples available per channel in engine

Hardware Configuration Properties

ChannelSkew	Specify time between consecutive scanned hardware channels
ChannelSkewMode	Specify how channel skew is determined
ClockSource	Specify clock that governs hardware conversion rate
InputType	Specify analog input hardware channel configuration
SampleRate	Specify per-channel rate at which analog data is converted to digital data, or vice versa

Callback Properties

DataMissedFcn	Specify callback function to execute when data is missed
InputOverRangeFcn	Specify callback function to execute when acquired data exceeds valid hardware range
RuntimeErrorFcn	Specify callback function to execute when run-time error occurs
SamplesAcquired	Indicate number of samples acquired per channel
SamplesAcquiredFcn	Specify callback function to execute when predefined number of samples is acquired for each channel group member
SamplesAcquiredFcnCount	Specify number of samples to acquire for each channel group member before samples acquired event is generated
StartFcn	Specify callback function to execute before device object runs
StopFcn	Specify callback function to execute after device object runs
TimerFcn	Specify callback function to execute when predefined time period passes
TimerPeriod	Specify time period between timer events
TriggerFcn	Specify callback function to execute when trigger occurs

General Purpose Properties

BufferingConfig	Specify per-channel allocated memory
BufferingMode	Specify how memory is allocated
Channel	Contain hardware channels added to device object
EventLog	Store information for specific events
Name	Specify descriptive name for the channel
Tag	Specify device object label
Timeout	Specify additional waiting time to extract or queue data
Type	Indicate device object type, channel, or line
UserData	Store data to associate with device object

Examples

To create an analog input object for a National Instruments device defined as 'Dev1':

AI = analoginput('nidaq','Dev1');

To create an analog input object for a Measurement Computing device defined as '1':

AI = analoginput('mcc','1');

Alternatives

See Also

addchannel | daqhwinfo

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