Serial port
interface using labview
Aim:- To access the device
having serial port (like weighing machine)
using labview.
Objectives:-
1.
To connect computer with external device
(weighing machine) having serial port.
2.
To read the data from serial port of computer
through the labview.
3.
To understand functions of different blocks those
are use for serial communication.
4.
To understand the serial port of computer.
Introduction to serial port:-
|
Pin no
|
Description
|
|
1
|
Data carrier detect
|
|
2
|
Receive data
|
|
3
|
Transmit data
|
|
4
|
Data terminal ready
|
|
5
|
Signal ground
|
|
6
|
Data set ready
|
|
7
|
Request to send
|
|
8
|
Clear to send
|
|
9
|
Ring indicator
|
Procedure:-
o
Connect serial port of external device (weighing
machine) to the computer through RS_232 cable.
o
Open “Hyper terminal”, select the com port (0 or
1), select the baud rate (2400) and check whether information (data) through
serial port is coming or not.
o
After satisfactory result open labview.
o
Take a block of “VISA configure serial port” in
block diagram panel of labview.
Path :- (right click on block diagram
panel ,instrument I/O, serial
block, VISA configure serial port)
o
Give the visa resource name (com port 1), give
the baud rate 2400, add parity block and set the time for read operation which
is necessary for VISA configure serial port as shown below.
Out of all these pins we use only few pins
as below
Figure:- VISA configure serial port
block.
o
Take a case structure for continues data reading
in true case, in false case terminate the loop (or just bypass the data if
condition is wrong).
o
For case selector mode take a button to start or
stop reading process.
Read the data from serial port by using “VISA read” block.
Path :- (right click on block diagram
panel, instrument I/O, serial
block, VISA read)
o
These are in bundle like [05025], separate the
bracket by “Search and replace string” block.
Path :- (right click on block diagram
panel, programming, string, additional string functions, search
and replace patter block)
o
Each “Search and replace string” block remove
only one bracket therefore use two blocks for removing two bracket.
o
This result is in string and we want number, for
that use string to number block.
Path :- (right click on block diagram
panel, programming, string, string/number conversion, fract/exp string to number block)
o
String to number block give us weight in gram.
o
Convert gram to kilogram (by simple
multiplication and division blocks) and according to that display item,
quantity and price.
o
To select number of item take dropdown menu bar
as shown below
Path :- (right click on front
panel, express, menu string block)
o
Select different items like Rice, Dal and Nuts
according to that we can see the quantity and price.
o
This weighing scale allows weight up to 10
kilogram.
o
When we put weight more than 9Kg OVER FLOW indicator
will on.
o
For the above reason use comparator.
On front panel we get window like
this
On block diagram panel we get window
like this
REFERENCES
Core LabVIEW Concepts
LabVIEW Environment Basics – VI, front
panel, block diagram, palettes, controls, and indicators
(Link:- http://www.ni.com/gettingstarted/labviewbasics/environment.htm)
Dataflow Programming Basics – dataflow,
wires, and data types
(Link:- http://www.ni.com/gettingstarted/labviewbasics/dataflow.htm)
Common Tools – tools palette,
shortcut menus, property dialogs, and the front panel toolbar
(Link:- http://www.ni.com/gettingstarted/labviewbasics/tools.htm)
Debugging Tools – fixing broken
VIs, execution highlighting, and the block diagram toolbar
(Link:- http://www.ni.com/gettingstarted/labviewbasics/debug.htm)
Programming in LabVIEW
(Link:-
http://www.ni.com/gettingstarted/labviewbasics/exestructures.htm)
Data Structures
– arrays, clusters, and enumerated data
(Link:-
http://www.ni.com/gettingstarted/labviewbasics/datastructures.htm)
Passing Data
between Loop Iterations – shift registers
(Link:- http://www.ni.com/gettingstarted/labviewbasics/shiftregisters.htm)
Handling Errors
– error handling and error clusters
(Link:- http://www.ni.com/gettingstarted/labviewbasics/handlingerrors.htm)
Finding Examples and Getting Help
Finding Examples – Example Finder
and ni.com/code
(Link:-
http://www.ni.com/gettingstarted/labviewbasics/examples.htm)
Using the LabVIEW
Help – context help and the LabVIEW help
(Link:-
http://www.ni.com/gettingstarted/labviewbasics/producthelp.htm)
Online Help
Resources – Knowledge Base and forums
(Link:-
http://www.ni.com/gettingstarted/labviewbasics/onlinehelp.htm)
Getting Additional
Help – help from a LabVIEW expert
THANK YOU
s
