Real-Time Module on NI Linux Real-Time Targets

Special Considerations

Keep the following considerations in mind when using an NI Linux Real-Time target. You also can visit and enter the Info Code Linux to learn more about the NI Linux Real-Time operating system.


  • The FTP server is disabled by default, and you cannot use it in safe mode. NI recommends using WebDAV as the file transfer mechanism for improved security.
  • Virtual memory is supported, which implies the following:
    • A process crash restarts the process without restarting the target.
    • Monitoring the largest contiguous memory block does not provide useful or necessary information on NI Linux Real-Time targets.
  • System Exec VI is supported.
  • Time zone changes do not require a target restart.

File System and Directory Structure

  • The file system is case-sensitive.
  • Directory paths display in Linux format. For example, paths use forward slashes and do not contain drive letters. If you open a VI created for Phar Lap ETS or VxWorks targets in an NI Linux Real-Time target context, the Windows-like paths automatically convert to Linux-like paths.
  • NI Linux Real-Time targets enforce file and folder access permissions. Refer to the KnowledgeBase for information about these permissions.
  • The RTOS deletes the content in the temporary folder /tmp on target restart. The temporary folder allocates space from RAM up to a maximum size of 64 MB.
  • The c:\ni-rt directory does not exist on NI Linux Real-Time targets. Refer to the KnowledgeBase for information about the directory mapping on NI Linux Real-Time targets.
  • Direct modification of the ni-rt.ini configuration file is highly discouraged. Modification of this file may result in incorrect system behavior.
    Note  Some NI troubleshooting procedures require manual edits to this file. Take care to precisely follow troubleshooting documentation in these scenarios.

Web Services

  • WebDAV is enabled by default.
  • SSL is enabled by default.
  • NI Web-based Configuration & Monitoring is available in safe mode.
  • It is only possible to configure a target reachable via IP address (DHCP, link-local, or static). mDNS is used for target discovery.
  • You cannot use the Console Out using NI Web-based Configuration & Monitoring on NI Linux Real-Time targets. Instead, connect your NI Linux Real-Time targets to a computer using a serial port to view the output of the Console Out. Refer to the KnowledgeBase for detailed information about how to use the Console Out.


  • You can log in to a target using NI Web-based Configuration & Monitoring, SSH, or a serial connection. Refer to your hardware documentation to learn about enabling SSH on your RT target.
    Note  NI recommends you set a password to log in using SSH or a serial connection.
  • To reset a forgotten administrator password, you must physically access the target and reset all settings to the factory default. Contact NI for assistance with this process.
  • Your target creates an admin user that is equivalent to the root user in Linux systems.
    Caution  Do not create users in NI Web-based Configuration & Monitoring with the same name as system accounts. For example, do not create a user named root or ssh. Doing so overwrites the system account.
  • SSH supports public keys as an alternate form of authentication.


  • Visit and enter the Info Code RTSecurity to keep informed about security as it relates to NI products.

Unsupported Features

The LabVIEW Real-Time Module does not support certain LabVIEW features for VIs that run on RT targets. For instance, if you attempt to deploy and run a VI that has unsupported functionality on an RT target, the VI might still execute. However, the unsupported functions do not work and return standard LabVIEW error codes. The LabVIEW Real-Time Module does not support the following features on RT targets that run the NI Linux Real-Time RTOS:

  • ActiveX VIs
  • NI TestStand VIs (ActiveX-based)
  • .NET VIs
  • Report Generation VIs
  • Windows Registry Access VIs
  • Report Express VI (Uses the unsupported Report Generation VIs)
  • Graphics & Sound VIs
  • Database Connectivity VIs
  • Menu functions
  • Cursor VIs
  • IrDA functions
  • File System Web Service LabVIEW API
  • Analysis Workspace to Reduce Jitter in Mathematics and Signal Processing VIs
  • Call Library Function Nodes that access an operating system API other than NI Linux Real-Time
  • Open/Create/Replace File function interactively using a file dialog box
  • Clear indicators when called option of the Execution Properties page
  • Auto Configure option of the Create Histogram Express VI
  • Certain Advanced TDMS functions
  • Certain MathScript functions
    Note   Certain MathScript functions are supported on RT targets only when you assign the output of the function to a MathScript variable.
  • Profile Buffer Allocations window
  • Output Page of the LabVIEW MathScript Probe window—You can use the rt_debugoutput function to send debug strings to the standard output device instead.
  • Largest Available Memory Block Property Node—This property node does not provide useful information for NI Linux Real-Time targets and returns an error if used. Use the Free Physical Memory property node instead.
  • Latch Until Released and Switch Until Released Boolean mechanical actions—Refer to the KnowledgeBase for information about why these Boolean mechanical actions do not work on RT targets.


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