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LabVIEW 2020 Real-Time Module Known Issues

Created Jun 20, 2023

Overview

This document contains the LabVIEW 2020 Real-Time Module known issues that were discovered before and since the release of LabVIEW 2019 Real-Time Module. Known issues are performance issues or technical bugs that NI has acknowledged exist within this version of the product.

 

Not every issue known to NI appears on this list; it is intended to show the most severe and common issues that you may encounter and provide workarounds when possible. Other technical issues that you may encounter could occur through normal product use or system compatibility issues. You may find more information on these issues in NI’s Product Documentation, Knowledgebase, or Community.

Known Issues

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Bug Number

Legacy ID

Description

Details
60957 541200

Cursor Reference returned by the Cursor Move event not valid on LinuxRT x64 target with the Embedded UI enabled.

When obtaining the cursor reference returned by the cursor move event, the output is not valid on NI Linux Real-Time x64 targets with the Embedded UI enabled.

Workaround:

Obtain the reference from a graph control property node.

Reported Version:

LabVIEW Real-Time Module 2014 SP1

Resolved Version:

N/A

Added:

Mar 7, 2016
60958 543061

Error 56 Thrown When Using "Disconnect from Slave" Invoke Method

Using the "Disconnect from Slave" invoke method will almost immediately generate error 56; however the method functions correctly and disconnects the NI Real-Time system from the host machine.

Workaround:

Ignore error.

Reported Version:

LabVIEW Real-Time Module 2015

Resolved Version:

N/A

Added:

Mar 7, 2016
166718 654235

If 2 classes call separate instances of a polymorphic VI and an instance is included within the a class, the VI will break when compiled into an RTEXE.

A VI will break when compiled into an RTEXE if the VI contains multiple classes that call a polymorphic VI and the a copy of the polymorphic VI is in one of the classes.

Workaround:

Add the polymorphic VI to each instance of the class.

Reported Version:

LabVIEW Real-Time Module 2016

Resolved Version:

N/A

Added:

May 18, 2018
170895 514879

Running a VI Using Invoke Node Fails When Embedded UI is Enabled

When Embedded UI is enabled, using a LabVIEW Invoke Node to run a VI on NI Linux Real-Time results in an error about the Front Panel not being available. Using an Invoke Node to run a VI on NI Linux Real-Time works as expected if Embedded UI is disabled.

Workaround:

Instead of using an Invoke Node, use the Start Asynchronous Call with the connector pane of the target VI wired into the Open VI Ref.

Reported Version:

LabVIEW Real-Time Module Unknown

Resolved Version:

N/A

Added:

May 18, 2017
170896 580414

RT LEDs VI Returns Incorrect Error Code on Invalid Input

When selecting invalid parameter for a cRIO controller for the RT LED VI the error code and origin is incorrect. It should be error code one and the source should point to the RT LED.vi

Workaround:

There is currently no known workaround for this issue.

Reported Version:

LabVIEW Real-Time Module 2015

Resolved Version:

N/A

Added:

Mar 28, 2016
206134 700007

CPU load may be incorrectly reported when using Timed Loops on NI Linux Real-Time

In NI Linux Real-Time, the CPULoadTotal property node may incorrectly report the CPU Load when Timed Loops are used as part of the application.

Workaround:

There is currently no known workaround for this issue.

Reported Version:

LabVIEW Real-Time Module 2017

Resolved Version:

N/A

Added:

Apr 23, 2020
181570 720212

Calling the DAQmx Write VI after DAQmx Create Timing Source on NI Linux Real-Time can error depending on the DAQ hardware.

In NI Linux Real-Time, the DAQmx Commit occurs once the timing source is created. If a DAQmx Write is called after, hardware that does not support Non-Buffered HW-Timed Tasks can error.

Workaround:

Switch the two calls.

Reported Version:

LabVIEW Real-Time Module 2019

Resolved Version:

N/A

Added:

Apr 23, 2020

Final Time Issue Listed

Issues found in this section will not be listed in future known issues documents for this product.

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Bug Number

Legacy ID

Description

Details
60963 567919

Creating a User Named 'lvuser' on NI Linux Real-Time Overrides Native 'lvuser' Account

When using the Web-based Configuration & Monitoring tool to create or edit user accounts on a Linux RT target, the WIF allows creation of an account named "lvuser" or any of the other native Linux RT user accounts. Creating an account of the same name overrides the privileges of the native account. The default privileges for a new account are the same as the "Everyone" group, but not the "Admin" group. Unless admin permissions are added to this new account, issues can crop up using this account.

Workaround:

Avoid adding an 'lvuser' account or make sure this new account has admin privileges.

Reported Version:

LabVIEW Real-Time Module 2015

Resolved Version:

N/A

Added:

Mar 7, 2016
206167 540869

Behavior of App.Kind Property Node in Linux x64 RT targets Embedded UI Returns Invalid Property

Querying the App.Kind property returns Run-time System regardless of whether it is in development or executable state

Workaround:

There is currently no known workaround for this issue.

Reported Version:

LabVIEW Real-Time Module 2014 SP1

Resolved Version:

N/A

Added:

Mar 7, 2016
891081 677278

Directory permissions may change on NI Linux Real-Time when modifying files via WebDAV.

When modifying a directory via WebDAV on NI Linux Real-Time, the directory permissions may change to read-only.

Workaround:

Manually change the permissions back to read and write access as necessary.

Reported Version:

LabVIEW Real-Time Module 2017

Resolved Version:

N/A

Added:

May 18, 2018
320902 553905

Mass Compile Fails when using VIs from the RT Utilities Palette

If a VI running on an RT target uses a subVI from the RT Utilities palette, the VI cannot be mass compiled without errors as long as the project or VI are open during the compile.

Workaround:

Close the project and VI and run the mass compile again. It should run successfully.

Reported Version:

LabVIEW Real-Time Module 2015

Resolved Version:

N/A

Added:

Mar 7, 2016
399608 399608

RT FIFO writes produce high level of jitter on Linux-RT targets

On Linux-RT ZYNQ based targets, writes to an RT FIFO can introduce a high level of jitter compared to VxWorks and PharLap targets when the RT FIFO read occurs on a thread running in a different processor core.

Workaround:

Prioritize RT FIFO read and write operations so they take place in threads running on the same processor core.

Reported Version:

LabVIEW Real-Time Module 2013

Resolved Version:

N/A

Added:

Jul 22, 2013

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Glossary of Terms

 

  • Bug ID - When an issue is reported to NI, you may be given this ID or find it on ni.com.  You may also find IDs posted by NI on the discussion forums or in KnowledgeBase articles.
  • Legacy ID – An older issue ID that refers to the same issue.  You may instead find this issue ID in older known issues documents.
  • Description - A few sentences which describe the problem. The brief description given does not necessarily describe the problem in full detail.
  • Workaround - Possible ways to work around the problem.
  • Reported Version - The earliest version in which the issue was reported.
  • Resolved Version - Version in which the issue was resolved or was no longer applicable. "N/A" indicates that the issue has not been resolved.
  • Date Added - The date the issue was added to the document (not the reported date).