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DAQmx Create Virtual Channel (Analog Input » Strain Gage) (G Dataflow)

Last Modified: September 18, 2017

Creates channel(s) to measure strain.

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task in

task in specifies the task to which to add the virtual channels this node creates. If you do not specify a task, NI-DAQmx creates a task for you, and adds the virtual channels this node creates to that task.

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physical channels

physical channels specifies the names of the physical channels to use to create virtual channels. The DAQmx physical channel constant lists all physical channels on devices and modules installed in the system.

You can also wire a string that contains a list, or range of physical channels, to this input. If you have an array of physical channels, use the DAQmx Flatten Channel String node to convert the array to a list.

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name to assign

name to assign specifies a name to assign to the virtual channel this node creates. If you do not wire a value to this input, NI-DAQmx uses the physical channel name as the virtual channel name.

If you use this input to provide your own names for the virtual channels, you must use the names when you refer to these channels in other NI-DAQmx nodes, such as the source input of the DAQmx Trigger node.

If you create multiple virtual channels with one DAQmx Create Virtual Channel node, you can specify a comma-separated list of names to assign to the virtual channels. If you provide fewer names than the number of virtual channels you create, NI-DAQmx automatically assigns names to the virtual channels.

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units

units specifies the units to use to return strain measurements.

Name Description
From Custom Scale

Units a custom scale specifies. If you select this value, you must wire a custom scale name to the custom scale name input.

Strain

Strain.

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error in

error in describes error conditions that occur before this node runs. This input provides standard 'error in' functionality.

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measurement range

measurement range specifies the minimum and maximum values you expect to measure.

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maximum value

maximum value specifies in units the maximum value you expect to measure.

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minimum value

minimum value specifies in units the minimum value you expect to measure.

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custom scale name

custom scale name specifies the name of a custom scale for the channel.

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bridge information

bridge information specifies information about the bridge configuration and measurement.

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strain configuration

strain configuration specifies the bridge configuration for the strain gages.

Name Description
Full Bridge I

Full Bridge I.

Full Bridge II

Full Bridge II.

Full Bridge III

Full Bridge III.

Half Bridge I

Half Bridge I.

Half Bridge II

Half Bridge II.

Quarter Bridge I

Quarter Bridge I.

Quarter Bridge II

Quarter Bridge II.

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voltage excitation source

voltage excitation source specifies the source of excitation.

Name Description
External

Use an excitation source other than the built-in excitation source of the device. If you select this value, you must use the voltage excitation value input to specify the amount of excitation.

Internal

Use the built-in excitation source of the device. If you select this value, you must use the voltage excitation value input to specify the amount of excitation.

None

Supply no excitation to the channel.

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voltage excitation value

voltage excitation value specifies in volts the amount of excitation supplied to the sensor. Refer to the sensor documentation to determine appropriate excitation values.

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lead wire resistance

lead wire resistance is the amount of resistance in ohms in the lead wires. Ideally, this value is the same for all leads.

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initial bridge voltage

initial bridge voltage specifies in volts the output voltage of the bridge in the unloaded condition. NI-DAQmx subtracts this value from any measurements before applying scaling equations. Perform a voltage measurement on the bridge with no strain applied to determine this value.

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strain gage information

strain gage information contains information about the strain gage and measurement.

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gage factor

gage factor specifies the sensitivity of the strain gages and relates the change in electrical resistance to the change in strain. Each gage in the bridge must have the same gage factor. Refer to the sensor documentation to determine this value.

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nominal gage resistance

nominal gage resistance is the resistance in ohms of the gages in an unstrained position. Each gage in the bridge must have the same nominal gage resistance. The resistance across arms of the bridge that do not have strain gages must also be the same as the nominal gage resistance. Refer to the sensor documentation to determine this value.

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poisson ratio

poisson ratio is the ratio of lateral strain to axial strain in the material you are measuring.

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task out

task out is a reference to the task after this node runs. The task contains any newly created virtual channels. If you did not wire a value to task in, NI-DAQmx automatically creates the task this output refers to.

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error out

error out contains error information. If error in indicates that an error occurred before this node ran, error out contains the same error information. Otherwise, error out describes the error status that this node produces.

Where This Node Can Run:

Desktop OS: Windows

FPGA: LabVIEW NXG does not support FPGA devices

Web Server: Not supported in VIs that run in a web application


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