Why do you want to do that? LabVIEW Real-Time Targets (like the sbRIOs) may "look like" stand-alone PCs, but they are really designed to run as the Real-Time "partner" of a Host routine running on a PC. In this configuration, the "safe" place to store data files is on the PC, with the data transferred from the sbRIO to the PC over TCP/IP (I use Network Streams to manage this transfer for me). If you want to keep "parameters" as part of your program, i.e. a local "Data" folder where the sbRIO, while running, can read and write local files, that is easily accomplished by using the \Data folder that the Build creates for you as part of the Destinations category. If you look at the default Build Spec, you'll see that your .rtexe goes into /home/lvuser/natinst/bin, and Support Directory (which I think is there by default) shows up as /home/lvuser/natinst/bin/data. But how, you might ask, do you remember this? Answer -- you don't, you ask LabVIEW to create it for you!
Here's what you do:
- Open your Real-Time Project, which should have a section ("My Computer") for the Host code and a section ("sbRIO", with IP address) for the Real-Time part.
- Create a folder at the top level of the Host LabVIEW code called "Data". I organize my Projects so that there is a top-level "Project Folder" that contains the .lvproj file and (almost all of) the Host and Target LabVIEW code (I tend to organize them in sub-Folders for neatness and ease of finding elements later). If I look on my PC's hard drive at the contents of the Project Folder, I see that it contains both the "Data" folder and the <Projectname>.lvproj file.
- To access the Data folder, look in the File I/O Palette under File Constants. The Data Folder, whose folder name is "Data", is located as a sub-folder under the folder pointed to by the function "Application Directory". Do a "Build Path" with "Application Directory" as the Folder, and "Data" as the Relative Path.
- OK, but how does that help you with finding the Data Folder in your built Application? It is in exactly the same place, because (in an Executable) the Application Directory points to where the .exe (or .rtexe) is stored!
Having said all this, I am not routinely doing File I/O on the RT side. I do, however, use this "trick" on the Host -- during development, when I run from within LabVIEW, my test data files go into the \Data folder within my Project. But when I build (and deploy) an Executable (.exe) on the Host, it goes in a \Data folder that is one level down from the folder where <My Routine>.exe is stored as part of the Build specification.
Bob Schor
