The location in which you configure instrument session names depends on the type of session. For IVI sessions, configure the logical and virtual instrument names using a utility, such as Measurement & Automation Explorer (MAX).

You can use all the IVI aliases for a session, including logical names and the virtual instrument name, with or without the VInstr prefix. For example, for the same session, you might use SampleDMM, VInstr->FL45, or FL45.

Session Manager maintains VXIplug&play and VISA configuration information in the NISessionMgr.ini file, located in the <VXIplug&play directory>\WinNT or Win64 directory (for example, C:\<Program Files>\IVI Foundation\VISA\WinNT\NISessionMgr.ini). The NISessionMgr.ini file defines the VXIplug&play logical and virtual instrument names and the VISA logical names. Session Manager calls the VISA function viFindRsrc("?*INSTR") to obtain the list of VISA resource names.

If you change the NISessionMgr.ini file or the IVI settings in MAX, Session Manager loads the changes the next time you query for the available session names or request a new session object. The settings of an existing session object do not change when you alter a configuration file. If you release all references to a session and then request the same session, Session Manager recreates the session with the new configuration settings.

NISessionMgr.ini Configuration File

NISessionMgr.ini is a session manager, virtual instrument, or configuration file that you use to associate a hardware resource with a VXIplug&play driver and assign a virtual instrument name to the combination of the hardware resource and VXIplug&play driver. You can also use this file to assign logical names to VXIplug&play virtual instruments and VISA resources.

If the NISessionMgr.ini file does not exist, Session Manager automatically regenerates it by scanning the contents of the IVI Foundation\VISA directory to create a default entry for each installed VXIplug&play driver. The generated file uses the following format:

[VXIPNP Logical Names]

<logical name> = <virtual instrument name>

<another logical name> = <another virtual instrument name>

[VISA Logical Names]

<logical name> = <VISA resource name>

<another logical name> = <another VISA resource name>

Session Manager ignores VXIplug&play virtual instruments that do not specify all the following fields:

[VPPVInstr-><virtual instrument name>]

ModulePath = <dll path>

Prefix = <instrument prefix>

Resource = <VISA hardware resource>

IDQuery = <True or False>

Reset = <True or False>

The following list shows examples of VXIplug&play virtual instruments that might occur in the generated file:

[VXIPNP Logical Names]

DMM1 = "VPPVInstr->FlukeDMM"

[VISA Logical Names]

Serial1 = "ASRL1::INSTR"

[VPPVInstr->FlukeDMM]

ModulePath = "C:\Program Files\IVI Foundation\VISA\WinNT\Bin\fl45_32.dll"

Prefix = "FL45"

Resource = "GPIB::14::INSTR"

IDQuery = True

Reset = True

When Session Manager generates the NISessionMgr.ini file, each VXIplug&play virtual instrument resource tag is an empty string. You must edit the file to specify the resource for each virtual instrument. Session Manager ignores virtual instruments that do not specify a resource.

Use the following guidelines to edit the NISessionMgr.ini configuration file:

  • Each virtual instrument name defaults to the instrument prefix.
  • Edit the section name to rename a virtual instrument.
  • You can copy existing sections to create new virtual instruments.
  • Session Manager does not create any default logical names.
Note   Session Manager obtains configuration information about IVI drivers from MAX. By default, MAX does not specify whether to perform an ID query or a reset operation when initializing a virtual instrument. If you do not specify otherwise, Session Manager always performs the ID query and reset operation. You can add entries to the NISessionMgr.ini file to explicitly specify whether Session Manager performs these operations. To specify the operation settings in the NISessionMgr.ini file, add a virtual instrument definition section for the IVI virtual instrument, as shown in the following example:

[VInstr->FL45]

Reset = True

IDQuery = False

Refer to the NISessionMgr.ini file in the IVI Foundation\VISA\WinNT or Win64 directory for more information about the contents of this file.