Seneca5 Software Blog

July User Group – Circular Buffer in LabVIEW

Craig Bedward — Wed, 07 Jul 2010 15:35:57 +0000

Ludwik Kordas presented the concept of a Circular Buffer (CB) and various ways to implement it in LabVIEW.

His presentation and example VI’s are included in this post.

Definition

An area of memory used to store a continuous stream of data by starting again at the beginning of the buffer after reaching the end. A circular buffer is usually written by one process and read by another. Separate read and write pointers are maintained. These are not allowed to pass each other otherwise either unread data would be overwritten or invalid data would be read.

Simple CB Models

FIFO: first IN first OUT
(first WRITTEN first READ)
Number of elements: n+1
Predefined # of elements: n
“n+1” element is forbidden for write/read pointers
Elements could be of any data type including arrays, clusters or even clusters of arrays of clusters

July 2010 User Group Invite

Craig Bedward — Mon, 05 Jul 2010 17:33:40 +0000

July 6th, first day back from 4th of July vacation is the next user group meeting.

Topic: LabVIEW Design Patterns – Producer/Consumer, other demos

This meeting will be at Seneca5, Tuesday July 6th at 6:30.

Please note: We will NOT be serving pizza.

Check out the LabVIEW Advanced User Group page for more details.

VIG Example – Stopwatch

Craig Bedward — Sun, 04 Jul 2010 19:35:06 +0000

A VIG or “functional global” is a LabVIEW VI that provides the features of a global variable while overcoming some of the down sides of an actual global variable.

A function global uses uninitialized shift registers to maintain state information and a typedef function to select the mode of operation.

This example implements a stopwatch timer. You can use it to time up to 16 independent events in your application.

For more information on functional globals, check out these links:

Basic Functional Global Example

Functional Global Flags to Protect a Shared Resource

Other “functional global” examples in NI Developer Zone

Download the Code here:

May User Group Pictures – Popcorn Tweets

Craig Bedward — Wed, 23 Jun 2010 20:08:12 +0000

A cool contraption, a bunch of geeks, and pizza. What more could you want?

Certified LabVIEW Associate Developer (CLAD) Example Tests

Craig Bedward — Thu, 10 Jun 2010 21:14:21 +0000

There was a lot of interest at our last group meeting about NI certification tests.

The Certified LabVIEW Associate Developer (CLAD) is the first step in getting certified. The test shows knowledge of LabVIEW basics. If you have had the LabVIEW Basics class (now called Core 1) or if you have some real-life experience with LabVIEW, you might be ready. If you want to find out, there are some sample tests you can download from NI’s web site:

clad_sample_exam1.pdf

clad_sample_exam2.pdf

Certified LabVIEW Associate Developer (CLAD) Sample Exams

How Can I Prepare for the Certified LabVIEW Associate Developer (CLAD) Exam?

Popcorn Trivia

Craig Bedward — Thu, 10 Jun 2010 21:03:56 +0000

There was some discussion during the Popcorn Tweets demonstration about where the interest in the device came from. Although people from all over the world watched the video, Justin was surprised that a lot of the interest came from Brazil. Another member of our group Andrés, who is from Brazil, said that popcorn is a big deal there…and he has provided photographic evidence, a street vendor in São Paulo:

June 2010 User Group Invite

Craig Bedward — Sat, 29 May 2010 05:36:51 +0000

Mark your calendar. First day back from Memorial Day vacation is the next user group meeting.

Topic: LabVIEW Design Patterns – VIG Timer, Producer/Consumer, and more

This meeting will be at Seneca5, Tuesday June 1st at 6:30. We serve pizza, so you can come straight from work.

Check out the LabVIEW Advanced User Group page for more details.

May 2010 NI User Group

Craig Bedward — Sun, 09 May 2010 19:14:01 +0000

Ready, Aim…

This month, Seneca5 will once again be presenting at the quarterly National Instruments LabVIEW User Group.

Description
Seneca5 will be presenting a technical demonstration on vision and motion. Using a Compact Vision System and a Firewire camera, users will interact with a video feed to control an aiming device.

Demonstrates
NI Compact Vision System, IMAQ vision software, servo control
Lunch will be provided by National Instruments

05/11/2010 | 11:30 a.m. – 01:00 p.m.
Manchesters Grill
2121 T.W. Alexander Drive
Morrisville, NC

It is an NI event and lunch will be served, so you do have to register (but its FREE!). Get more information and register here.

You may also be interested…
Seneca5 hosts the regular meeting of the LabVIEW Advanced User Group at our office each month.

May 2010 User Group Invite

Craig Bedward — Thu, 29 Apr 2010 02:15:25 +0000

It’s time again for our monthly LabVIEW user group meeting. The topic this time is “Popcorn Tweets”. Justin Goeres of JKI will be presenting his Rube Goldberg contraption that pops popcorn based on Twitter activity on the word “popcorn”.

If you have ever wanted to write a complicated LabVIEW program to use Lego parts and other miscellaneous hardware to make popcorn based on how much strangers are talking about popcorn on Twitter, this is just the meeting for you!

This meeting will be at Seneca5, Tuesday May 4th at 6:30. We serve pizza, so you can come straight from work.

Check out the LabVIEW Advanced User Group page for more details.

April 2010 User Group Follow-up

Craig Bedward — Wed, 07 Apr 2010 22:28:42 +0000

We had a great meeting discussing motor control of all types. Thanks to all who attended.

Many people offered information on websites and products they have used. I wanted to capture some of them here in case anyone wants to check into them:

Motor drivers for hobby servos

phidgets.com
geckodrive.com
seetron.com/ssc.htm (serial control of 8 hobby servos)
parallax (serial controller that Michael used in his demo)
servocity (good source for hobby servos and accessories)
US Digital (optical rotary encoders)

National Instruments Tools

Other Items

Any additions? Comment them here. This group works best when we share ideas!