IVI Step Types

TestStand 2019 Help

Edition Date: May 2019

Part Number: 370052AA-01

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Use the IVI step types to configure and acquire data from Interchangeable Virtual Instrument (IVI)class instruments. Use an initial IVI step to configure an instrument and use one or more subsequent IVI steps to perform measurements.

Note Note  (64-bit TestStand) 64-bit TestStand does not support IVI step types.

TestStand includes the following IVI step types:

TestStand uses the instrument logical name to reference a session to an instrument. Use National Instruments Measurement & Automation Explorer to configure instrument logical names. TestStand initializes the instrument session when you first configure the instrument and closes the instrument session when the execution closes. When two executions reference the same logical name, TestStand shares the session, and the session closes when TestStand releases the last execution of the two.

IVI step types use the National Instruments Session Manager to share named instrument connections. You can also use Session Manager to share instrument connections in code modules even when you do not use IVI step types. Refer to the NI Session Manager Help. located in <Program Files>\National Instruments\Shared\Session Manager, for more information about how to use Session Manager.

Although you can use IVI steps to configure and acquire data from IVI class instruments, you must use code modules for the following tasks and situations:

  • To control instruments to ensure optimal performance by precisely specifying the instrument driver calls
  • To call specific driver functions an IVI class does not support
  • To interleave instrument control operations with other code that must reside in a single code module
  • When the instrument does not conform to an IVI class
  • When no IVI driver exists for the instrument

Right-click an IVI step and select Edit <step type> from the context menu to configure and select an operation for the step to perform. You can also click the Edit <step type> button on the edit tab of the Step Settings pane.

When TestStand configures an instrument, the instrument driver might force a settings value. Configuring an instrument in TestStand might result in an error that indicates an invalid value for a particular setting because TestStand does not validate the instrument-based values until the configuration actually occurs. When you edit a step that configures an instrument, click the Validate button in the Edit IVI <Step Name> dialog box to test the configuration before you close the dialog box.

Use the instrument soft front panel, which is a graphical display panel for the instrument, to interact directly with the instrument session TestStand controls.

To edit an IVI step type in the TestStand Sequence Editor, click the Edit <Step Type Name> button on the edit tab of the Step Settings pane.

To edit an IVI step type in a TestStand User Interface, select Edit from the context menu for the step or click Edit on the General tab of the Step Properties dialog box.

Notes Notes
  • With IVI-C drivers, you cannot use the same instrument driver session in more than one operating system process simultaneously.
  • The instrument handles that TestStand IVI step types create cannot be used within LabVIEW VIs that execute using the LabVIEW development environment. The underlying C-based handle can only be used within the TestStand process. If the LabVIEW code modules invoke IVI class- and driver-specific VIs, National Instruments does not recommend using the TestStand IVI step types at the same time.

See Also

Effectively Using LabVIEW with TestStand

Instrument Drivers

IVI Step Types (Example)

Session Manager (Example)

Session Manager Support for 64-bit TestStand

Step Properties dialog box

Step Settings Pane

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