LabVIEW: Tips & Tricks
Ihor Korolov
March 2011
Contents
 GPIB communication
 VISA: GPIB and Serial port configuration and communication
 How to create and use *.dll in LabVIEW (C++ example)
 LabVIEW Tips and tricks:
VI hierarchy
Event structure
Application control (property node and invoke node)
How to execute system command
…..
 Creating an executable VIs
 Remote panel connection manager and Web publishing tool
I. Korolov: LabVIEW: Tips & Tricks
GPIB
I. Korolov: Tips & Tricks
GPIB
General Purpose Interface Bus (GPIB)
(IEEE-488 is a short-range digital communications bus specification)
8 data lines, 3 Handshaking lines, 5 Interface management lines
HS488 can transfer up to 8 Mbytes/s (2 m cable)
All GPIB devices and interfaces
must have a unique GPIB
address between 0 and 30.
Address 0 is normally
assigned to the GPIB
interface. The instruments on
the GPIB can use addresses
1 through 30. GPIB devices
can be talkers, listeners, or
controllers.
I. Korolov: LabVIEW: Tips & Tricks
GPIB
General Purpose Interface Bus (GPIB)
(IEEE-488 is a short-range digital communications bus specification)
8 data lines, 3 Handshaking lines, 5 Interface management lines
HS488 can transfer up to 8 Mbytes/s (2 m cable)
GPIB-USB
I. Korolov: LabVIEW: Tips & Tricks
GPIB-RS232
GPIB-PCI
GPIB - LabVIEW
Use the GPIB 488.2 functions to exchange data and instructions between VIs and GPIB 488 devices
You should consider initializing
the bus with the "GPIB
Initialization" function before
starting R/W
I. Korolov: LabVIEW: Tips & Tricks
Virtual Instrument Software Architecture
I. Korolov: Tips & Tricks
NI-VISA
Virtual Instrument Software Architecture (VISA)
is a standard for configuring, programming, and troubleshooting instrumentation
systems comprising GPIB, VXI, PXI, Serial, Ethernet, and/or USB interfaces.
The majority of modern instrument drivers are based on theVISA
NI-VISA is the National Instruments implementation of the VISA I/O standard
Software libraries
Interactive utilities
Configuration programs
(NISpy, VISA interactive control)
(MAX)
The creation of a new VISA driver in LabVIEW is relatively straightforward and quick process
LabVIEW Application
LabVIEW VI Library
VISA
Operating System
Hardware Link
(GPIB, Serial, VXI …)
Instrument
I. Korolov: LabVIEW: Tips & Tricks
GPIB - VISA
Simple GPIB-VISA session
Open
Write
command/data
Read
data
Close
 Open a VISA Session to the instrument resource. Also set the timeout.
 Write command from the Write Buffer control to the device
Read the data returned from the NI
 Close the VISA Session.
If possible, try to use the VISA functions instead of GPIB because of VISAs versatility
I. Korolov: LabVIEW: Tips & Tricks
GPIB- VISA
Using serial ports
Serial communication uses a transmitter to send
data, one bit at a time, over a single
communication line to a receiver
Serial (RS-232) port
4 x RS-232 to PCI
RS-232 to USB
No Flow Control
PC
2
3
5
Device
2
3
5
Cable connection over RS-232 interface
For hardware flow control (RTS/CTS)
Connector pins definition
I. Korolov: LabVIEW: Tips & Tricks
VISA serial
Simple Serial-VISA session (similar to GPIB-VISA)
Configure
Serial port
Write
command/data
Write bytes to port.
Read
data
Close
Read the number of bytes specified
Close session to port
Configure Serial port
(baud rate, data bits,
parity, stop bits and flow
control)
I. Korolov: LabVIEW: Tips & Tricks
Closing the serial port allows it to be used by
other applications without quitting LabVIEW.
Note: To read an information from a serial
instrument, first run the “Bytes at Port” vi. This VI
checks how many bytes of information are
waiting at the serial port. Use this VI in a while
loop to wait for a specified number of bytes
accumulated in the buffer before you read the
information.
Serial- VISA and driver
How to create and use DLL
I. Korolov: Tips & Tricks
What is DLL?
Dynamic-Link Library
DLL is a file which does a particular job, and allows other programs to use
its efforts in assisting the program's job. Some programs use a DLL so that
they won't need to spend time figuring out how to do that job*
Applications and DLLs can link to other DLLs
How to create *.dll (C++ example)
Borland C++ Compiler
(Free)
(Free)
Code::Blocks (New project)
Our function
The WinAPI, is Microsoft core set
of
application
programming
interfaces (APIs) available in
Microsoft Windows op. systems
*www.dynamiclink.nl/frames/about_dll.htm
I. Korolov: LabVIEW: Tips & Tricks
This function is called
when DLL is loaded or
unloaded
How to create DLL?
The syntax of a function declaration
In Borland C/C++
DWORD
Long
WINAPI
WINAPI
Function
Function
(DWORD a, DWORD b, …..);
(float *a, long b, float *c, ….);
In Microsoft C++
_declspec (dllexport) DWORD
Function (DWORD a, DWORD b, …..);
_declspec (dllexport) long WIAPI Function (float *a, long b, float *c, ….);
Func1 = a + b
a0 = a*a*a
b0 = b*b
avg = (a[0] + a[1] +…+ a[size-1]) / size
I. Korolov: LabVIEW: Tips & Tricks
Code blocs
How to create DLL?
Our dll
The header file *.h
All of the functions we have created in the source code are
available to other applications
Build dll
I. Korolov: LabVIEW: Tips & Tricks
Code blocs
How to use DLL in LabVIEW?
???
The DLL can be called by using the LabVIEW Call Library Function
1. Path (dll location)
2. Function name
I. Korolov: LabVIEW: Tips & Tricks
How to use DLL in LabVIEW?
???
Data types LabVIEW/C++
unsigned char
unsigned short
unsigned long
……………….
BYTE; // 8-bit
WORD; // 16-bit
DWORD; // 32-bit
………………….*
*http://msdn.microsoft.com/en-us/library/cc230309%28v=PROT.10%29.aspx
Instrument
1.dll
I. Korolov: LabVIEW: Tips & Tricks
2.dll
ExampleDLLs
Tips & Tricks
I. Korolov: Tips & Tricks
VI hierarchy
View
VI Hierarchy
The “VI Hierarchy” window displays a
graphical representation of all open
LabVIEW projects and targets, as well as
the calling hierarchy for all VIs in
memory, which includes type definitions,
global variables, LabVIEW classes and
dynamic member VIs, etc. Use this
window to view the subVIs and other
nodes that make up the VIs in memory
and to search the VI hierarchy*.
Redo Layout—Repositions the hierarchy nodes after you expand, collapse, or move nodes.
Vertical Layout—Arranges the nodes from top to bottom, placing roots at the top of the layout.
Horizontal Layout—Arranges the nodes from left to right, placing roots on the left side of the layout.
Include VI Lib—Includes VIs in labview\vi.lib in the hierarchy layout.
Include Globals—Toggles the hierarchy layout to include or exclude global variables.
Include Type Definitions—Toggles the hierarchy layout to include or exclude type definitions.
*http://zone.ni.com
I. Korolov: LabVIEW: Tips & Tricks
Example LP MD
Event structure
The Event structure waits until an event happen, then
executes appropriate case to handle that event
 Place the event structure on the block diagram
 Right click on the structure border
 Configure which events to handle
I. Korolov: LabVIEW: Tips & Tricks
Add event case
Example Event
Scroll Through Structure
Use Ctrl + Mouse Scroll to scroll through:
 Case Structures
 Event Structures
 Stacked Sequence Structures
 Diagram Disable Structures
Ctrl
+
I. Korolov: LabVIEW: Tips & Tricks
Example Scroll
Property node and Invoke node
Property nodes is used to get and set
VI, object, or application properties
Right click
Invoke nodes is used to perform
actions, or methods on VI object, or
application
Property node
The “OK” button
will start blinking
if the “Blinking”
button is pressed
I. Korolov: LabVIEW: Tips & Tricks
Example PN
Property node: Cursors
Cursors:
 assist in viewing data points
 can be assigned to different plots
 lock to plot to help reading data
I. Korolov: LabVIEW: Tips & Tricks
Example PN
Open VI Reference
This method requires a path to *.vi
I. Korolov: LabVIEW: Tips & Tricks
Example PN
Sound, Dialog and User interface
Sound
Dialog and
User interface
Run a system command
This code will run a windows calculator
I. Korolov: LabVIEW: Tips & Tricks
Examples
Creating an Executable
I. Korolov: Tips & Tricks
Creating an executable
With the Application Builder, you can create an executable from any operational
LabVIEW VI that will run as a standalone program on any other machine with the
same operating system.
Save Vi
New project (add)
Build specification ->Right click
New -> Application (exe)
I. Korolov: LabVIEW: Tips & Tricks
Creating an executable
Build specification ->Right click
New -> Application (exe)
2
3
1
4
I. Korolov: LabVIEW: Tips & Tricks
Creating an executable
 After you have pressed the "Build" button and
Application Builder finishes writing the executable
to disk, you are ready to run it.
 Regardless of your Application Builder and
LabVIEW version, you must always install any
required driver files on the target machine (e.g.
NI-DAQ, NI-488.2)
Install LabVIEW Runtime engine on your
target computer (~100 MB). The runtime engine
allows you to run LabVIEW executables without
needing further LabVIEW on your or target PC.
Run your application.exe on the target computer
You can also create an installer:
I. Korolov: LabVIEW: Tips & Tricks
Build specification ->Right click
New -> Installer
example
Remote panel
Web publishing tool
I. Korolov: Tips & Tricks
Remote panel and VI/Web server
Remote Panels allow multiple clients to simultaneously view/control the front
panel of the same VI
LAN
Client machine
Controlling remote panel
WAN
Server machine
Main panel and Application
Client machine
Viewing remote panel
I. Korolov: LabVIEW: Tips & Tricks
Remote panel connection manager
Two main steps to connect:


Enable the LabVIEW VI/Web Server on the server machine
Connect and execute remote panels on the client machine
1
Tools
Options
I. Korolov: LabVIEW: Tips & Tricks
Allow access
Operate
2
Connect to remote panel…
example
Web server
The “web publishing tool” is used to view the front panels of VIs on the Web.
! Do not forge to enable the LabVIEW Web Server on the server machine
Web publishing tool
Tools
Web browser
To display front panels on the Web, the
VIs must be in memory on the computer
Local PC
I. Korolov: LabVIEW: Tips & Tricks
Example MD
Useful links
National instruments
www.ni.com/labview
Tips and Tricks on the LabVIEW Wiki
http://labviewwiki.org/Tips_and_tricks
Learn LabVIEW
http://learnlabview.blogspot.com
Books
http://astore.amazon.com/lealab-20
NI forum
www.forums.ni.com
I. Korolov: LabVIEW: Tips & Tricks
Köszönöm for your attention!
I. Korolov: LabVIEW: Tips & Tricks