How Do I Access the Storage on My Real-Time Controller?

Updated Dec 22, 2023

Reported In


  • cFP-2220
  • PXI Controller
  • cRIO-9049


  • LabVIEW
  • Measurement & Automation Explorer (MAX)


  • NI-FieldPoint
  • NI CompactRIO

Operating System

  • NI Linux Real-Time

Issue Details

I want to write data to the storage on my NI Real-Time target, how can I access the available storage?


The Real-Time controller you are using determines which storage features will be available for your system.

Internal Storage

The internal storage of a Real-Time controller can be accessed programmatically in an embedded program using the regular File I/O VIs. The file path structure differs depending on the Real-Time Operating System (RTOS) your controller is running. That file path syntax is documented in the Tutorial: Working with File Paths on Real-Time Targets . You can identify which RTOS your target is running by looking at the System Settings tab of your device in Measurement & Automation Explorer (MAX) or by searching for your model number in the Real-Time Controllers and Real-Time Operating System Compatibility.

You are also able to transfer files manually. Real-Time controllers can be configured to support WebDAV which will allow you to manually transfer files to and from the target in a secure manner. If you would prefer to not use WebDAV and do not mind a less secure method you can configure the controller to use an FTP connection. Refer to the Using WebDAV to Transfer Files to Real-Time Target .

​USB Storage

The external mass storage device attached to a USB port on a Real-Time controller can be accessed as drive U: using the File I/O VIs; similarly to how internal storage was accessed. You can FTP to the drive as well by specifying the drive letter. The drive letter will increment to W:, X:, and Y: with when more USB storage devices are attached. To access these drives you would specify a FTP connection similar to, ftp://IP_address_of_FP_controller/U:/.

External CompactFlash Storage 

Real-Time controllers, like the cFP-2x20, that use compactFlash for external storage can be accessed as drive D: using the File I/O VIs.  In order to access the file data.csv in the root directory of the external CompactFlash, use the File I/O VIs to read the file D:\data.csv.  The CompactFlash card can also be accessed using a FTP connection.