CHAPTER 9. POS TERMINAL
69
(a) Representative images
(b) Vision Assistant script
(c) LabVIEW project file set
9.1
Technical Approach
NI Vision Assistant Script
NI Vision Assistant provides the
Barcode Reader
step as a flexible and easy-to-
use method to detect 1-D barcodes from among ten different standards including
“EAN 13” (European Article Number) and the essentially equivalent “UPC-A”
(Universal Product Code). This step can even detect multiple barcodes of differ-
ent types, all within the same image. The
Barcode Reader
step is scale invariant
(the barcode can be any size) as well as rotation invariant (the barcode angle does
not matter); the only requirement is that the barcode must be in focus with suffi-
cient spatial resolution to resolve the black and white bar pattern. Study
to learn how to set up the
Barcode Reader
step.
The Vision Assistant Express VI offers two indicators for the
Barcode
Reader
; use the
Barcodes
output. This output is an array because the reader
can read multiple barcodes at once. Use the following techniques to interpret
the barcode output:
1. Use the
Index Array
function to retrieve a single barcode and connect this
to a custom control in the data highway,
T
IP
:
Use the “Quick Drop” shortcut (Ctrl + space bar) to look up
and place a LabVIEW element by name. See Appendix C on page 139
for more LabVIEW tips.
2. The “Data” element of the barcode output is a string that contains the nu-
merical code. Use the
Empty String/Path?
function to determine whether
or not a valid barcode is in view, and
3. Use the
Decimal String To Number
function to convert the “Data” element
string to an
[I64]
integer; wire a zero-valued constant of this data type to
the
default
input.
(1:29)
Summary of Contents for NI myRIO
Page 1: ...Ed Doering NI myRIO Vision Essentials Guide...
Page 2: ......
Page 11: ...Part I Machine Vision Fundamentals...
Page 12: ......
Page 31: ...Part II Introductory Machine Vision Projects...
Page 32: ......
Page 38: ...32 CHAPTER 4 CAMERA SETUP...
Page 44: ...38 CHAPTER 5 STEREO VISION...
Page 61: ...Part III Machine Vision Application Projects...
Page 62: ......
Page 72: ...66 CHAPTER 8 COIN COUNTER...
Page 86: ...80 CHAPTER 10 KEYED OPTICAL LOCK...
Page 92: ...86 CHAPTER 11 DMM TEST STAND...
Page 134: ...128 CHAPTER 17 MARBLE SORTER...
Page 135: ...Part IV Appendices...
Page 136: ......
Page 143: ...B MXPandMSPConnectorDiagrams Figure B 1 MXP myRIO eXpansion Port connector diagram...
Page 144: ...138 APPENDIX B MXP AND MSP CONNECTOR DIAGRAMS Figure B 2 MSP miniSystem Port connector diagram...
Page 148: ...142 APPENDIX D BUILD A STAND ALONE APPLICATION...
Page 149: ...E MarbleSorterConstructionDetails To be continued...
Page 150: ...144 APPENDIX E MARBLE SORTER CONSTRUCTION DETAILS...
