Channel Properties

Get Property Information

You can use the get, set, and properties functions to get information on channel object properties. For example, create a DataAcquisition and add a voltage measurement input channel, then view the channel properties:

d = daq("ni");
ch = addinput(d,"Dev1",1,"Voltage");
get(ch)

       Coupling: DC
 TerminalConfig: Differential
          Range: -10 to +10 Volts
           Name: 'Dev1_ai1'
             ID: 'ai1'
         Device: [1x1 daq.ni.DeviceInfo]
MeasurementType: 'Voltage'

View the channel settable properties and their acceptable values:

set(ch)

      Coupling: [ DC | AC ]
TerminalConfig: [ Differential | SingleEnded | SingleEndedNonReferenced | PseudoDifferential ]
         Range: -10 to +10 Volts
          Name: {}

Change the channel range and terminal configuration:

ch.TerminalConfig = "SingleEnded"

ch = 

    Index    Type    Device    Channel      Measurement Type             Range              Name   
    _____    ____    ______    _______    _____________________    __________________    __________

      1      "ai"    "Dev1"     "ai1"     "Voltage (SingleEnd)"    "-10 to +10 Volts"    "Dev1_ai1"

You can also request help in the Command Window on a specific property, providing either the object and property, or the class name and property. For example:

help ch.TerminalConfig

or

help ("daq.AnalogInputVoltageChannel.TerminalConfig")

 TerminalConfig The current input type (single ended/differential)

All Channels

All channel objects have these properties in common for all measurement types:

Property	Description	Values
Name	Channel name	character vector constructed of device ID and channel ID
ID	Channel identifier corresponding to device terminal ID	character vector, for example: 'ai0' 'ao3' 'Port2/Line1' 'ctr0'
Device	DeviceInfo object for device with this channel	DeviceInfo object handle
MeasurementType	Type of measurement	character vector, for example: 'Voltage' 'Current' 'Thermocouple' 'Digital' 'Audio'

Analog Input and Output Channels

• Voltage Measurement

• Current Measurement

Voltage Measurement

Input voltage measurement channel objects also include these properties:

Property	Description	Values
Range	Input value range	Vector of two double values specifying minimum and maximum, depending on measurement type and device support. For example: ch.Range = [-5 5]
Coupling	Coupling mode of the channel	character vector of: 'AC' 'DC'
TerminalConfig	Channel terminal configuration as described in Channel Configuration	character vector of: 'Differential' 'SingleEnded' 'SingleEndedNonReferenced' 'PseudoDifferential'

Current Measurement

Current measurement channel objects also include these properties:

Property	Description	Values
Current Input
Range	Input value range	Vector of two double values specifying minimum and maximum, depending on measurement type and device support. For example: [-0.1 0.1]
Coupling	Coupling mode of the channel	character vector of: 'AC' 'DC'
TerminalConfig	Channel terminal configuration as described in Channel Configuration	character vector of: 'Differential' 'SingleEnded' 'SingleEndedNonReferenced' 'PseudoDifferential'
Current Input and Output
ShuntLocation	(Only some vendors) Indicates if the shunt resistor is located internally on the device or externally	character vector of: 'Internal' 'External'
ShuntResistance	(Only some vendors) Indicates shunt resistance in ohms	double

Other Analog Measurements

• Thermocouple Measurement

• Accelerometer Measurement

• RTD Measurement

• Bridge Measurement

• Microphone Measurement

• IEPE Measurement

Thermocouple Measurement

Thermocouple measurement input channel objects also include these properties:

Property	Description	Values
ThermocoupleType	Type of thermocouple based on temperature range and sensitivity, according to the NIST Thermocouple Types Definitions.	character vector of: 'J' 'K' 'N' 'R' 'S' 'T' 'B' 'E'
Units	Temperature units	character vector of: 'Celsius' (default) 'Fahrenheit' 'Kelvin' 'Rankine'
Range	Input value range	Vector of two double values specifying minimum and maximum, depending on measurement type and device support. For example: [-1 1]

Accelerometer Measurement

Accelerometer measurement input channel objects also include these properties:

Property	Description	Values
Sensitivity	Sensitivity of accelerometer channel expressed as volts per g-force, V/g	double
ExcitationCurrent	Current to excite an IEPE accelerometer, IEPE microphone, generic IEPE sensor, or RTD, specified in amperes.	double
ExcitationSource	Indicates source of excitation for IEPE sensor or RTD	character vector of: 'Internal' 'External' 'None' 'Unknown'
Coupling	Coupling mode of the channel	character vector of: 'AC' 'DC'
TerminalConfig	Channel input configuration as described in Channel Configuration	character vector of: 'Differential' 'SingleEnded' 'SingleEndedNonReferenced' 'PseudoDifferential'
Range	Input value range	Vector of two double values specifying minimum and maximum, depending on measurement type and device support. For example: [-1 1]

RTD Measurement

RTD measurement input channel objects also include these properties:

Property	Description	Values
Units	Temperature units	character vector of: 'Celsius' (default) 'Fahrenheit' 'Kelvin' 'Rankine'
RTDType	Specify the sensitivity of a standard RTD 100-ohm platinum sensor	character vector of: 'Pt3750' 'Pt3851' 'Pt3911' 'Pt3916' 'Pt3920' 'Pt3928'
RTDConfiguration	Specify the wiring configuration for measuring resistance	character vector of: 'TwoWire' 'ThreeWire' 'FourWire'
R0	Specify the resistance of this device to a reference temperature	double
ExcitationCurrent	Current to excite an IEPE accelerometer, IEPE microphone, generic IEPE sensor, or RTD, specified in amperes	double
ExcitationSource	Indicates source of excitation for IEPE sensor	character vector of: 'Internal' 'External' 'None' 'Unknown'
Coupling	Coupling mode of the channel	character vector of: 'AC' 'DC'
TerminalConfig	Channel input configuration as described in Channel Configuration	character vector of: 'Differential' 'SingleEnded' 'SingleEndedNonReferenced' 'PseudoDifferential'
Range	Input value range	Vector of two double values specifying minimum and maximum, depending on measurement type and device support. For example: [-1 1]

Bridge Measurement

Bridge measurement input channel objects also include these properties:

Property	Description	Values
BridgeMode	Bridge mode representing the active gauge of the analog input channel	character vector of: 'Full' — All four gauges are active. 'Half'— Only two bridges are active. 'Quarter'— Only one bridge is active.
ExcitationSource	Indicates source of excitation voltage	character vector of: 'Internal' 'External' 'None' 'Unknown'
ExcitationVoltage	Indicates the excitation voltage value to apply to bridge measurements	double
NominalBridgeResistance	Resistance of a bridge-based sensor in ohms	double
Range	Range of input values	Vector of two double values specifying minimum and maximum, depending on measurement type and device support. For example: [-1 1]

Microphone Measurement

Microphone measurement input channel objects also include these properties:

Property	Description	Values
Sensitivity	Microphone channel sensitivity in volts per pascal, V/Pa	double
MaxSoundPressureLevel	Maximum sound pressure of the microphone channel in decibels	double
ExcitationCurrent	Current to excite an IEPE accelerometer, IEPE microphone, generic IEPE sensor, or RTD, specified in amperes.	double
ExcitationSource	Indicates source of excitation for IEPE sensor	character vector of: 'Internal' 'External' 'None' 'Unknown'
Coupling	Coupling mode of the channel	character vector of: 'AC' 'DC'
TerminalConfig	Channel input configuration as described in Channel Configuration	character vector of: 'Differential' 'SingleEnded' 'SingleEndedNonReferenced' 'PseudoDifferential'
Range	Input value range	Vector of two double values specifying minimum and maximum, depending on measurement type and device support. For example: [-1 1]

IEPE Measurement

IEPE measurement input channel objects also include these properties:

Property	Description	Values
ExcitationCurrent	Current to excite an IEPE accelerometer, IEPE microphone, generic IEPE sensor, or RTD, specified in amperes.	double
ExcitationSource	Indicates source of excitation for IEPE sensor	character vector of: 'Internal' 'External' 'None' 'Unknown'
Coupling	Coupling mode of the channel	character vector of: 'AC' 'DC'
TerminalConfig	Channel input configuration as described in Channel Configuration	character vector of: 'Differential' 'SingleEnded' 'SingleEndedNonReferenced' 'PseudoDifferential'
Range	Input value range	vector of two double values specifying minimum and maximum, depending on measurement type and device support

Digital Channels

Digital channel objects include the following properties:

Property	Description	Values
Direction	Direction of data flow, changeable only for bidirectional channels	character vector of: 'Input' 'Output'

Counter Channels

• All Counter Channels

• Edge Count

• Frequency

• Position

• Pulse Width

• Pulse Generation

All Counter Channels

Counter input and output channel objects also include these properties:

Edge Count

Counter input edge count channels also include the following properties:

Property	Description	Values
ActiveEdge	Indicates rising or falling edge of edge count signal	character vector of: 'Rising' 'Falling'
CountDirection	Indicates counting up or down	character vector of: 'Increment' 'Decrement'
InitialCount	Value to count from	uint32
Terminal	Terminal on device	character vector, for example 'PFI2'

Frequency

Counter input frequency measurement channels also include the following properties:

Property	Description	Values
ActiveEdge	Indicates rising or falling edge of edge count signal	character vector of: 'Rising' 'Falling'
Terminal	Terminal on device	character vector, for example: 'PFI2'

Position

For an overview of position measurement, including signals, encoding types, and Z-indexing, see National Instruments™ Encoder Measurements: How-To Guide. See also Measure Angular Position with an Incremental Rotary Encoder.

Counter input position measurement channels also include the following properties:

Property	Description	Values
EncoderType	Specify the encoding type of the counter input	character vector of: 'X1' 'X2' 'X4' 'TwoPulse'
ZResetEnable	Allow the Z-indexing to be reset	logical
ZResetValue	Specify the reset value for Z-indexing on a counter input	numeric
ZResetCondition	Specify reset conditions for Z-indexing of counter	character vector of: 'AHigh' 'BHigh' 'BothLow' 'BothHigh'
InitialCount	Specify the point from which the device starts the counter	double value, typically 0
TerminalA	External terminal on device	character vector, for example: 'PFI0'
TerminalB	External terminal on device	character vector, for example: 'PFI1'
TerminalZ	External index terminal on device for zero or reference signal	character vector, for example: 'PFI2'

Pulse Width

Counter input pulse width measurement channels also include the following properties:

Property	Description	Values
ActivePulse	Indicates active level	character vector of: 'High' 'Low'
Terminal	External terminal on device	character vector, for example: 'PFI2'

Pulse Generation

Counter output pulse generation channels also include the following properties:

Property	Description	Values
IdleState	Indicate the default state of the counter output channel when not running	character vector of: 'High' 'Low'
InitialDelay	Specify an initial delay on the counter output channel before pulse generation	double value in seconds
Frequency	Specify the pulse repetition rate of a counter output channel	double value in Hz
DutyCycle	Specify the fraction of time that the generated pulse is in active state, as a portion of 1.0. A square wave has a duty cycle of 0.5.	double
Terminal	External terminal on device	character vector, for example, 'PFI2'

Audio Channels

Audio input and output channel objects also include these properties:

Property	Description	Values
Range	Input/output value range	[-1.0 1.0]

Function Generator Channels

Function generator channel objects also include these properties:

Property	Description	Values
Range	Output value range	Vector of two double values specifying minimum and maximum, depending on measurement type and device support. For example: [-5 5]
TerminalConfig	Channel input configuration as described in Channel Configuration	character vector of: 'Differential' 'SingleEnded' 'SingleEndedNonReferenced' 'PseudoDifferential'
Gain	Specify amplification of scan data for channel output.	double value between –5 and 5. Ensure that Gain x data + Offset falls within the valid Range of device output.
Offset	Specify offset of scan data for channel output.	double value between –5 and 5. Ensure that Gain x data + Offset falls within the valid Range of device output.
Frequency	Specify waveform frequency	double value in Hz, within FrequencyLimit value
Phase	Specify waveform phase shift in degrees	double, from 0 to 360
WaveformType	Specify waveform shape	character vector of: 'Sine' 'Square' 'Triangle' 'RampUp' 'RampDown' 'DC' 'Arbitrary'
FrequencyLimit	Minimum and maximum rates that the function generation channel supports	double