Table Of Contents

IviDmm Read (G Dataflow)

Last Modified: September 7, 2018

Initiates a measurement, waits until the DMM has returned to the Idle state, and returns the measured value.

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Note  

After this node executes, the Reading parameter contains an actual reading or a value indicating that an over-range condition occurred.

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instrument handle

The instrument handle that you obtain from the IviDmm Initialize Node. The handle identifies a particular instrument session.

Default: None

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error in

Error conditions that occur before this node runs.

The node responds to this input according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.

Default: No error

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maximum time

Value you pass indicating the maximum length of time in which to allow the multi-point fetch operation to complete. Express this value in milliseconds. If the operation does not complete within this time interval, the node returns the IVIDMM_ERROR_MAX_TIME_EXCEEDED (0xBFFA2003) error code. When this occurs, you can call IviDmm Abort to cancel the multi-point fetch operation and return the instrument to the Idle state. Defined Values:

IVIDMM_VAL_MAX_TIME_INFINITE (-1) Wait indefinitely for a timeout.
IVIDMM_VAL_MAX_TIME_IMMEDIATE (0) Do not wait for a timeout.
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Note  

The Maximum Time parameter affects only this node. It has no effect on other timeout parameters or properties.

Default: 5000 (ms)

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instrument handle out

The instrument handle that you obtain from the IviDmm Initialize Node. The handle identifies a particular instrument session.

Default: None

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error out

Error information.

The node produces this output according to standard error behavior.

Standard Error Behavior

Many nodes provide an error in input and an error out output so that the node can respond to and communicate errors that occur while code is running. The value of error in specifies whether an error occurred before the node runs. Most nodes respond to values of error in in a standard, predictable way.

error in does not contain an error error in contains an error
If no error occurred before the node runs, the node begins execution normally.

If no error occurs while the node runs, it returns no error. If an error does occur while the node runs, it returns that error information as error out.

If an error occurred before the node runs, the node does not execute. Instead, it returns the error in value as error out.
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reading

Returns the measured value. The value you specify for the Measurement Function parameter of the IviDmm Configure Measurement Node determines the units of this parameter as shown in the following table.

DC Volts volts
AC Volts volts
DC Current amperes
AC Current amperes
2-Wire Resistance ohms
4-Wire Resistance ohms
AC plus DC volts
AC plus DC Current amperes
Temperature celcius
Frequency hertz
Period seconds
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Note  

If an over-range condition occurs, the Reading parameter contains an IEEE defined NaN (Not a Number) value and the node returns the IVIDMM_WARN_OVER_RANGE (0x3FFA2001) warning code.

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Note  

You can test the measurement value for an over-range condition by calling the IviDmm Is Over-Range Node.

Default Values

This node applies default values to properties that have not been set by the user under the following conditions:
  1. If the user has not set the value of any property in the IviDmmMultiPoint extension group, the node sets the IviDmm>>Multi-Point Acquisition>>Sample Count [MP] and IviDmm>>Multi-Point Acquisition>>Trigger Count [MP] properties to 1.
  2. If the user has not set the value of the IviDmm>Measurement Operation Options>Auto Zero [AZ] property, the node sets the value of this property to IVIDMM_VAL_AUTO_ZERO_OFF (0).

Over-range Condition

If an over-range condition occurs, the Reading parameter contains an IEEE defined NaN (Not a Number) value and the node returns the IVIDMM_WARN_OVER_RANGE (0x3ffA2001) warning code.

Interchangeability Checking

This node performs interchangeability checking when the IviDmm>>Inherent IVI Settings>>User Options>>Interchange Check property is set to TRUE. If the IviDmm>>Inherent IVI Settings>>User Options>>Spy property is set to True, you use the NI Spy utility to view interchangeability warnings. You use the IviDmm Get Next Interchange Warning Node to retrieve interchangeability warnings when the IviDmm>>Inherent IVI Settings>>User Options>>Spy property is set to False. For more information about interchangeability checking, refer to the help text for the IviDmm>>Inherent IVI Settings>>User Options>>Interchange Check property.

Testing Measurement Values

You can test the measurement value for an over-range condition by calling the IviDmm Is Over-Range Node.

Simulated Measurements

The class driver returns a simulated measurement when this node is called and the IviDmm>>Inherent IVI Settings>>User Options>>Simulate property is set to True and the IviDmm>>Inherent IVI Settings>>User Options>>Use Specific Simulation property is set to False. For information on how to configure a simulated measurement, refer to the online help manual.

Where This Node Can Run:

Desktop OS: Windows

FPGA: Not supported

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


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