Table Of Contents

Strain Channel Properties (AI)

Last Modified: June 10, 2021

Configure analog input (AI) channel properties to measure strain.

For more information on measuring strain, refer to the NI-DAQmx Manual.

Property/Section Description
Minimum Value The minimum value you expect to measure before VeriStand performs any scaling or calibration.
Maximum Value The maximum value you expect to measure before VeriStand performs any scaling or calibration.
Strain Configuration Specifies what type of bridge configuration to use for the strain gages:
  • Full Bridge I
  • Full Bridge II
  • Full Bridge III
  • Half Bridge I
  • Half Bridge II
  • Quarter Bridge I
  • Quarter Bridge II
Excitation Source Specifies the source of excitation:
  • External—Use an external excitation source instead of the built-in excitation source of the device.
  • Internal—Use the built-in excitation source of the device.
  • None—Supply no excitation to the channel.

For both internal and external excitation sources, you must use the Excitation Value property.

Excitation Value Specifies the amount of excitation supplied to the sensor. Refer to the sensor documentation to determine this value.
Lead Resistance Specifies the amount of resistance in the lead wires. Ideally, this value is the same for all leads.
Initial Bridge Voltage Specifies the output voltage of the bridge in the unloaded condition. VeriStand 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.
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.
Nominal Gage Resistance Specifies the resistance 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.
Poisson Ratio Specifies the ratio of lateral strain to axial strain in the material you are measuring.
Enable Offset Null Specifies whether to perform a bridge offset nulling calibration.
Enable Shunt Calibration Specifies whether to perform a shunt calibration.
Shunt Element Location Specifies the location of the shunt resistor:
  • R1—Between Vch- and Vex+
  • R2—Between Vch- and Vex-
  • R3—Between Vch+ and Vex-
  • R4—Between Vch+ and Vex+
Shunt Resistance Specifies the shunt resistance.
Filter Type (supported devices only) Specifies whether to apply a digital filter to the input signal:
  • Disabled—No filter.
  • Lowpass—Eliminates all signal frequency components above the cutoff frequency.
Filter Cutoff Frequency (supported devices only) Specifies the cutoff frequency of the digital filter.
In-Situ Calibration (supported devices only) Specifies whether to perform an in-situ calibration and when to perform the calibration:
  • Before deployment—Perform an in-situ calibration before the system definition is deployed.
  • After undeployment—Perform an in-situ calibration after the system definition is no longer deployed.
  • Both—Perform an in-situ calibration before the system definition is deployed and after the system definition is no longer deployed.
  • None—Do not perform an in-situ calibration.
In-Situ Minimum Value (supported devices only) The minimum value you expect to measure when VeriStand performs an in-situ calibration.
In-Situ Maximum Value (supported devices only) The maximum value you expect to measure when VeriStand performs an in-situ calibration.
In-Situ Input Configuration (supported devices only) Specifies the input terminal configuration to use when performing the in-situ calibration:
  • Same as device—The same configuration specified for the DAQ device itself. To set the input terminal configuration at the device level, use the Input Configuration pull-down menu on the DAQ Device Configuration page.
  • Default—At run time, NI-DAQmx chooses the default terminal configuration for the channel.
  • RSE—Referenced single-ended mode.
  • NRSE—Non-referenced single-ended mode.
  • Differential—Differential mode.
  • Pseudodifferential—Pseudodifferential mode.

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