FlexLogger Modbus Plug-In Fails to Load a LabVIEW Class

Updated Sep 17, 2026

Reported In

Software

  • FlexLogger
  • LabVIEW
  • FlexLogger Plug-In Development Kit

Operating System

  • Windows

Issue Details

  • I developed a custom FlexLogger I/O Plug-In in LabVIEW using the FlexLogger Plug-In Development Kit.

  • The Plug-In communicates with a Modbus TCP device using the NI Modbus Library and includes dynamically loaded LabVIEW classes in a packed project library.

  • When I add the Plug-In to a project in FlexLogger 2024 Q2 or earlier, FlexLogger fails to load a LabVIEW class from the packed project library.

  • FlexLogger returns the following error:

 
Get LV Class Default Value.vi <b> Complete call chain: </b> Get LV Class Default Value.vi niPluginWrapper.lvlib:Load Plugin.vi:1310013 niPluginWrapper.lvlib:niPluginWrapper.vi:10012 _PE_ExecWrapper_Common.vi:5100053 _PE_ExecWrapper.vi:2040038 _PE_ExecWrapper.vi.ACBRProxyCaller.F9000294 <b> LabVIEW attempted to load the class at this path: </b> C:\Users\Public\Documents\National Instruments\FlexLogger\Plugins\IOPlugins\<custom plug-in name>\<custom plug-in name>.lvlibp:<custom plug-in name>.lvclass 
 

  • The error dialog may also display:

 
??? in PEF System Interface.lvclass:Get Resampling Parameters.vi->niPluginWrapper.lvlib:Setup Resampler.vi:5710032->niPluginWrapper.lvlib:Processing Loop.vi:3820013->niPluginWrapper.lvlib:niPluginWrapper.vi:10012->_PE_ExecWrapper_Common.vi:5100053->_PE_ExecWrapper.vi:2040038->_PE_ExecWrapper.vi.ACBRProxyCaller.F9000294 
 
 

Solution

This is a known issue in FlexLogger 2024 Q2 and earlier that was fixed in FlexLogger 2024 Q3. Upgrade to FlexLogger 2024 Q3 and complete the following steps to load the Plug-In successfully.

    1. Download and install FlexLogger 2024 Q3. Refer to Installing, Updating, Repairing, and Removing NI Software for installation and update instructions.

    2. Verify that your FlexLogger, LabVIEW 64-bit, and FlexLogger Plug-In Development Kit versions are compatible, and then rebuild the Plug-In. Refer to FlexLogger Plug-In Development Kit Compatibility with FlexLogger and LabVIEW.

      • Using incompatible versions may cause errors or missing functionality.

    3. Open your FlexLogger project and add the custom I/O Plug-In.

    4. Open the Plug-In configuration and verify that FlexLogger loads the Plug-In without displaying the class-loading error.

    5. Configure the Plug-In and confirm that the expected channels are available.

     

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