LabVIEW: Tips & Tricks

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 structureApplication 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)

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.

(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


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 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

Virtual Instrument Software Architecture


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.

NI-VISA is the National Instruments implementation of the VISA I/O standard

Software libraries Interactive utilities(NISpy, VISA interactive control)

Configuration programs(MAX)

The creation of a new VISA driver in LabVIEW is relatively straightforward and quick process

The majority of modern instrument drivers are based on theVISA

LabVIEW Application LabVIEW VI Library VISA Operating System

Hardware Link(GPIB, Serial, VXI …)

Instrument

GPIB - VISA


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.

Open Write

command/dataRead data

Close

Simple GPIB-VISA session

If possible, try to use the VISA functions instead of GPIB because of VISAs versatility

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

PC235

Device235

Cable connection over RS-232 interface

No Flow Control

Connector pins definition

RS-232 to USB4 x RS-232 to PCI

For hardware flow control (RTS/CTS)

VISA serial


Configure Serial port

Write command/data

Read data

Close

Simple Serial-VISA session (similar to GPIB-VISA)

Closing the serial port allows it to be used by other applications without quitting LabVIEW.

Configure Serial port (baud rate, data bits, parity, stop bits and flow control)

Write bytes to port. Read the number of bytes specified

Close session to port

Serial- VISA and driver

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.

How to create and use DLL


What is DLL?


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*

Dynamic-Link Library

*www.dynamiclink.nl/frames/about_dll.htm

Borland C++ Compiler

(Free) (Free)

How to create *.dll (C++ example)

Applications and DLLs can link to other DLLs

Code::Blocks (New project)

The WinAPI, is Microsoft core set of application programming interfaces (APIs) available in Microsoft Windows op. systems

This function is called when DLL is loaded or unloaded

Our function

How to create DLL?


In Borland C/C++

DWORD WINAPI Function (DWORD a, DWORD b, …..);Long WINAPI Function (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, ….);

The syntax of a function declaration

Func1 = a + b

a0 = a*a*ab0 = b*b

avg = (a[0] + a[1] +…+ a[size-1]) / size

Code blocs

How to create DLL?

I. Korolov: LabVIEW: Tips & Tricks Code blocs

Our dll The header file *.h

Build dll

All of the functions we have created in the source code are available to other applications

How to use DLL in LabVIEW?


???

1. Path (dll location)

2. Function name

The DLL can be called by using the LabVIEW Call Library Function

How to use DLL in LabVIEW?


???

Data types LabVIEW/C++

ExampleDLLs

unsigned char BYTE; // 8-bit unsigned short WORD; // 16-bit unsigned long DWORD; // 32-bit………………. ………………….*

*http://msdn.microsoft.com/en-us/library/cc230309%28v=PROT.10%29.aspx

Instrument

1.dll 2.dll

Tips & Tricks


VI hierarchy

I. Korolov: LabVIEW: Tips & Tricks Example LP MD

View 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.

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*.

*http://zone.ni.com

Event structure


The Event structure waits until an event happen, then executes appropriate case to handle that event

Example Event

Right click on the structure border Add event case Configure which events to handle

Place the event structure on the block diagram

Scroll Through Structure


Use Ctrl + Mouse Scroll to scroll through:

Case Structures Event Structures Stacked Sequence Structures Diagram Disable Structures

Ctrl+

Example Scroll

Property node and Invoke node

I. Korolov: LabVIEW: Tips & Tricks Example PN

Right click

The “OK” button will start blinking if the “Blinking” button is pressed

Property node

Property nodes is used to get and set VI, object, or application properties

Invoke nodes is used to perform actions, or methods on VI object, or application

Property node: Cursors

I. Korolov: LabVIEW: Tips & Tricks Example PN

assist in viewing data points can be assigned to different plots lock to plot to help reading data

Cursors:

Open VI Reference


This method requires a path to *.vi

Example PN

Sound, Dialog and User interface


SoundDialog and

User interface

This code will run a windows calculator

Examples

Run a system command

Creating an Executable


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 ViNew project (add)Build specification ->Right click New -> Application (exe)



1

2 3

4

Build specification ->Right click New -> Application (exe)


I. Korolov: LabVIEW: Tips & Tricks example

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: Build specification ->Right click New -> Installer

Remote panel Web publishing tool


Remote panel and VI/Web server


Server machineMain panel and Application

Client machineViewing remote panel

Client machineControlling remote panelLANLAN

WANWAN

Remote Panels allow multiple clients to simultaneously view/control the front panel of the same VI

Remote panel connection manager

I. Korolov: LabVIEW: Tips & Tricks example

Allow access Operate Connect to remote panel…

Enable the LabVIEW VI/Web Server on the server machine Connect and execute remote panels on the client machine

Tools Options

Two main steps to connect:

1 2

Web server

I. Korolov: LabVIEW: Tips & Tricks Example MD

Web publishing tool Tools

Local PC

Web browser

To display front panels on the Web, the VIs must be in memory on the computer

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

Useful links


http://labviewwiki.org/Tips_and_tricks

www.ni.com/labview

Tips and Tricks on the LabVIEW Wiki

National instruments

http://learnlabview.blogspot.com

Learn LabVIEW

http://astore.amazon.com/lealab-20Books

www.forums.ni.com

NI forum

Köszönöm for your attention!


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LabVIEW: Tips & Tricks

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