NI Linux Real-Time Documents
I had a need to plot data to a graph that could be inserted into a record for customer use. In previous projects I had use Windows LabVIEW VIs to accomplish this using the Plot XY VI which created a new picture that I would annotate and add cursors. Using the Picture to Pixmap VI, I could take the image data output and finally save to PNG using the Write PNG File VI. This worked well, but as my project goes more and more embedded I wanted to move this functionality to the cRIO 9074 in our system. Turns out this functionality is not available on the cRIO 9074 so I needed to find another solution. Since I knew I could potentially leverage Linux solutions on the new RT Linux controllers I set about finding a Linux solution. Using VMware I installed Fedora 23 to a VM and found a command line tool called gnuplot which could plot and make very complex and professional looking graphs. After being comfortable using gnuplot in a Linux environment I was ready to test on a NI RT Linux target.
First connected a cRIO 9033 to our local work network and had an IP address assigned. Using MAX I created a password for the admin account and installed the standard 2014 RT software package. The using Putty I established a connection to the cRIO and logged in using the admin password. Using opkg I was able to install gnuplot as follows:
From the command line it is possible to run gnuplot and type successive commands to plot and output to various terminals <gnuplot demos>. However the System Exec VI doesn't allow for successive command line calls. So to execute the totality of what was needed in gnuplot, I created a script containing all the commands needed for my application. Then using the System Exec VI I could call gnuplot to execute the script. The extension of "p" is totally random. The script just needs to be a text file following the instructions on gnuplot homepage.
Using the following LabVIEW code I was able to execute the script via gnuplot to create the desired PNG.
Progressing with more complicated features in gnuplot I was able to create some nice plots dynamically by opening and editing the script at run time to insert new data sets and labels. An example...
Update:
I had successfully loaded Gnuplot on a 9033 which has a 64 bit architecture. The gnuplot package was included in the opkg update from NI. However I now have a 9066 which is an ARM and Gnuplot is not listed in the feed. I forced the feed to the x64 and of course it won't load becuase it is not comptaible with the ARM architecture.
Searching on the internet I found an uncompiled packgae of gnuplot 'gnuplot-4.4.1.tar.gz'. I moved it to the target and tried to compile. But had problems compiling since I didn't have a proper compiler loaded on the 9066. To address this I found another NI forum post https://decibel.ni.com/content/thread/20236?start=15&tstart=0 and someone in there pointed out that gcc, etc. wouldn't have all the dependencies, and suggested
opkg update
opkg install packagegroup-core-buildessential
After doing this I downloaded the extracted the gnuplot-4.4.1.tar.gz to the lvuser folder and then was able to use
./configure
make
make install
Eventhough I was able to get gnuplot to compile directly on the target, I found that it was missing some libraries required to use the PNG terminal. After some digging around on the internet I found that I needed 'libgd' which is a support library for graphics drivers. Before I could use libgd properly I needed to compile another library called 'libpng', which went smoothly using "./configure", "make", "make install".
However when I went to compile the 'lingd' I noticed that the PNG library wasn't loading properly. To finally get it working properly I had to force the libpng location.
admin@NI-cRIO-9066-030c6c27:/home/lvuser# cd /home/lvuser/libgd-2.1.1
admin@NI-cRIO-9066-030c6c27:/home/lvuser/libgd-2.1.1# ./configure
** Configuration summary for libgd 2.1.1:
Support for Zlib: yes
Support for PNG library: no
Support for JPEG library: no
admin@NI-cRIO-9066-030c6c27:/home/lvuser/libgd-2.1.1# find / -name libpng
/home/lvuser/libpng-1.6.21/projects/vstudio/libpng
admin@NI-cRIO-9066-030c6c27:/home/lvuser/libgd-2.1.1# ./configure --with-png=/usr/local/
** Configuration summary for libgd 2.1.1:
Support for Zlib: yes
Support for PNG library: yes
Support for JPEG library: no
Support for VPX library: no
Support for TIFF library: no
Support for Freetype 2.x library: no
Support for Fontconfig library: no
Support for Xpm library: no
Support for pthreads: yes
admin@NI-cRIO-9066-030c6c27:/home/lvuser/libgd-2.1.1# make
admin@NI-cRIO-9066-030c6c27:/home/lvuser/libgd-2.1.1# make install
After success compile of 'libgd' it was time to recompile 'gnuplot'
admin@NI-cRIO-9066-030c6c27:/home/lvuser# cd /home/lvuser/gnuplot-4.4.1
admin@NI-cRIO-9066-030c6c27:/home/lvuser/gnuplot-4.4.1# ./configure
** Configuration summary for gnuplot 4.4.1:
gnuplot will be compiled with the following terminals:
Standalone terminals: yes (always builtin)
(canvas, cgm, corel, dumb, dxf, eepic, emf, emtex,
epslatex, epson_180dpi, epson_60dpi, epson_lx800, fig, gpic, hp2623A,
hp2648, hp500c, hpdj, hpgl, hpljii, hppj, imagen,
latex, metafont, metapost, mif, pbm, postscript, pslatex, nec_cp6, okidata,
pcl5, pstex, pstricks, qms, regis, svg, tandy_60dpi,
tek40xx, tek410x, texdraw, tgif, tkcanvas, tpic, vttek)
X Window System terminal: no (requires X libraries)
jpeg terminal: no (requires libgd with jpeg support)
gif terminal: yes (with animated gif)
png terminal: yes
(jpeg, gif and png terminals cannot use TTF fonts, requires libgd support)
admin@NI-cRIO-9066-030c6c27:/home/lvuser/gnuplot-4.4.1# make
admin@NI-cRIO-9066-030c6c27:/home/lvuser/gnuplot-4.4.1# make install
admin@NI-cRIO-9066-030c6c27:/# gnuplot
G N U P L O T
Version 4.4 patchlevel 1
last modified Fri Sep 10 12:10:34 PDT 2010
System: Linux 3.2.35-rt52-2.0.0f0
Copyright (C) 1986-1993, 1998, 2004, 2007-2010
Thomas Williams, Colin Kelley and many others
gnuplot home: http://www.gnuplot.info
faq, bugs, etc: type "help seeking-assistance"
immediate help: type "help"
plot window: hit 'h'
Terminal type set to 'unknown'
gnuplot> set terminal
Available terminal types:
canvas HTML Canvas object
cgm Computer Graphics Metafile
corel EPS format for CorelDRAW
dpu414 Seiko DPU-414 thermal printer [small medium large]
dumb ascii art for anything that prints text
dxf dxf-file for AutoCad (default size 120x80)
eepic EEPIC -- extended LaTeX picture environment
emf Enhanced Metafile format
emtex LaTeX picture environment with emTeX specials
epslatex LaTeX picture environment using graphicx package
epson_180dpi Epson LQ-style 180-dot per inch (24 pin) printers
epson_60dpi Epson-style 60-dot per inch printers
epson_lx800 Epson LX-800, Star NL-10, NX-1000, PROPRINTER ...
fig FIG graphics language for XFIG graphics editor
gif GIF images using libgd and TrueType fonts
gpic GPIC -- Produce graphs in groff using the gpic preprocessor
hp2623A HP2623A and maybe others
hp2648 HP2648 and HP2647
hp500c HP DeskJet 500c, [75 100 150 300] [rle tiff]
hpdj HP DeskJet 500, [75 100 150 300]
hpgl HP7475 and relatives [number of pens] [eject]
hpljii HP Laserjet series II, [75 100 150 300]
hppj HP PaintJet and HP3630 [FNT5X9 FNT9X17 FNT13X25]
imagen Imagen laser printer
latex LaTeX picture environment
mf Metafont plotting standard
mif Frame maker MIF 3.00 format
mp MetaPost plotting standard
nec_cp6 NEC printer CP6, Epson LQ-800 [monocrome color draft]
okidata OKIDATA 320/321 Standard
pbm Portable bitmap [small medium large] [monochrome gray color]
pcl5 HP Designjet 750C, HP Laserjet III/IV, etc. (many options)
png PNG images using libgd and TrueType fonts
postscript PostScript graphics, including EPSF embedded files (*.eps)
pslatex LaTeX picture environment with PostScript \specials
pstex plain TeX with PostScript \specials
pstricks LaTeX picture environment with PSTricks macros
qms QMS/QUIC Laser printer (also Talaris 1200 and others)
regis REGIS graphics language
starc Star Color Printer
svg W3C Scalable Vector Graphics driver
tandy_60dpi Tandy DMP-130 series 60-dot per inch graphics
tek40xx Tektronix 4010 and others; most TEK emulators
tek410x Tektronix 4106, 4107, 4109 and 420X terminals
Press return for more:
texdraw LaTeX texdraw environment
tgif TGIF X11 [mode] [x,y] [dashed] ["font" [fontsize]]
tkcanvas Tk/Tcl canvas widget [perltk] [interactive]
tpic TPIC -- LaTeX picture environment with tpic \specials
unknown Unknown terminal type - not a plotting device
vttek VT-like tek40xx terminal emulator
xterm Xterm Tektronix 4014 Mode
gnuplot>
