05-11-2012 03:29 PM
LabVIEW for Lego Mindstorms has 2 separate Functions Palettes. One of them appears when one creates a VI (.vi) for a Project (.lvrbt), and it appears to contain Mindstorms NXT functions. The other appears when one creates a stand alone VI (.vi), and it contains functions which are labelled "NXT Robotics" but which appear to be the old Mindstorms RCX functions. For example, the Motor Functions have no Speed or Duration controls. (See Control Palette pictures on the attached Word document.) (NI should be aware that the RCX is no longer sold or supported by Lego.)
If I only want to create a stand-alone VI, how do I access mature NXT functions with which to implement that VI?
05-16-2012 03:28 PM
Actually both sets of functions are for the NXT (not the RCX). The orange ones are meant to be used in remote mode(compiled/autonomous). The grey ones are meant to be used in direct mode(tethered).
The functionality of both modes are pretty similar but there are some differences. For example, there is no PID control exposed in the directMode API, hence no speed input, only power.
We recommend that you use the newer set of "dual mode" functions which will work in either scenario, (these are the subVIs with rounded corners). We include the old single mode sets for backwards compatibility.
05-16-2012 05:01 PM
I knew that the NXT could be controlled from a "remote" device (e.g. cell phone), though perhaps "remote" is a poor choice of words given your use of the word "direct" which, as you use it, has the same connotation. I have never run the NXT in the direct mode, nor have any of my team members. The reason I assumed that you had included RCX functions was RCX functions had fewer properties than NXT functions just like your "direct" functions do. I have no idea where the "dual mode" functions are to be found.
I think LVLM has inadequate introductory documentation.I have Gasperi's book, but like NXT-G books, he only gives recipes for robots with different functionalities. LVLM needs a better structural and functional description.
Lego Education is not supporting LVLM (nore is NI, for that matter, at least not very well...it was a lot of work to get to someone who knew what they were talking about). The guys at Lego Education are not in a position to support LVLM. Your guys also asked me to call "Tom Barrowman," Lego's New England sales rep. I didn't call him, but I am betting that he knows even less.
I understand why NI doesn't want to put the support bucks into LVLM. The license for LV cost $2500/year, and I bought LVLM for $100. LVLM was intended to be an introductory product for people (kids) who might become NI customers someday, but if those kids walk off in disgust because they can't figure out how to use LVLM, NI's investment in it will have been for nothing.
05-16-2012 05:41 PM
Dual Mode functions are under NXTIO at the top level of the palette. They should be more exposed than the single mode versions which are somewhat hidden since they are sort of deprecated. Are you using the 2009 or 2010 version of LVLM?
05-16-2012 05:42 PM
Also, you can always tell whether you are in direct or remote mode by looking at the bottom left corner of your vi. It will be orange with the name of your NXT if you are in remote mode, and gray with the words "main application instance" if you are in remote mode.