Use of shift register and similiar C code

Hello LabVIEW Gurus,
I am very new to LabVIEW and I did searched the forum for my short question but the answers were not that clear to me. My question is what is a shift register and could you please give me one similiar C code and where shift register can be used.
Thanks for your time.
Vasu

there is no direct analogous to a c construct to a labview shift register but a shift register is an unnamed temporary variable for use with itterative loop structures (for and while). See the following code
int sum = 0;
for(i=0; i>100: i++)
sum = sum + i;
return sum;
This can be done in LV without naming the variable sum . In addition the shift register can be initialized or not. If you do not register the shift register it will remember the value from call to call (a very cool feature when you learn to utilize it). See below
Paul
Paul Falkenstein
Coleman Technologies Inc.
CLA, CPI, AIA-Vision
Labview 4.0- 2013, RT, Vision, FPGA

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Iterative addition of 2D array using a shift register

Hi
I'm trying to add 2D array iteratively using a shift register.
However, the indicator for the output of 2D addition shows nothing.
Do you know Why? and How to fix this problem?
Thx
hiyang

Ok, looked at ur attached VI
You are not getting any output because, you are adding an array with an empty/blank array
First, initialise an array of zeroes of required size and pass it to shift register, Initialise your other array which u are adding inside the loop also of similiar dimension, and later, keep changing its elements
Do as shown in modification of your attached VI
Regards
Dev
Attachments:
2DArray_shiftRegister.vi ‏30 KB

Problem saving an array using a shift register

In the attached VI I'm building a 1D array of strings, then trying to save it using a shift register. For some reason my data isn't being saved and I dont understand why.
Thank you.
Solved!
Go to Solution.
Attachments:
Shift_Reg.vi ‏15 KB

Try this...
LabVIEW Champion . Do more with less code and in less time .
Attachments:
Shift_RegMOD.vi ‏10 KB

Using a shift register to detect input...

Hi guys,
I'm creating a LabVIEW VI that needs to be able to detect when a user changes an input. I read a previous post that suggested using clusters and shift registers to compare previous data.
My question is how do I use shift registers? I've created a shift register on a for loop, but I'm not sure when to compare the "previous" data to the "new" data. Do I need to add an element to the left side and compare it there? Is the right side the output? I'm just not sure how it works. An uploaded example would be nice. Thanks.
-Mike

Shift registers are very powerful but difficult to use for the first time.
The shift register you just created has two "arrows", one on either side of the structure. The arrow to the left is the value from the previous (i:th) iteration and the arrow to the right you have to feed with the (i+1)th value.
Now, if you want to compare values and look for a change you can compare your old value (the one coming out from the left) with the new value in your for loop. The feed your new value to the right arrow so that it becomes the old value for the next iteration.
If you have many parameters to compare, clusters are very useful since they make things very compact. If you are comparing clusters, do not forget to change the setting on the comparison to compare aggregates (r
ight click on it and select that option).
Also, in most cases you need to set the initial (start) value for your shift register. This is done by feeding the left arrow with the default value from the outside of your loop.
I attached a simple example, CompareSettings.vi, that shows how it works. Hope this helps. /Mikael"
Attachments:
comparesettings.vi ‏32 KB

Shift Register and waiting time functions - DAQmx

Thanks that worked.

Bob_Schor wrote:
Mike -- is there a reason to not use Shift Registers here? It seems to me that (as I explained in my response) it "preserves" the logic of folding multiple sequential function calls into a loop (you are correct, of course, that you don't need to pass the Task and Error from one function to the next, but that makes logical sense). It might (or might not -- I haven't checked) be a tad faster or slower (actually, it is almost certainly faster or slower!) one way or the other, but we are probably talking nanoseconds, which pales beside "logical" (a.k.a. "good") Programming Style.
For a While loop, there should not be real difference. It might be slightly more memory efficient. But if you go to a FOR loop, it is a HUGE deal, especially if you are autoindexing on a loop. Try running a FOR loop 0 times. If you used tunnels, the default value comes out of the tunnel (in other words, you will lose your reference). A shift register will pass out the value you initialized the shift register to.
So it is a good habit to just use the shift registers to avoid that nasty bug.

Problem in using the shift Register

I have a problem regarding shift register when i was using it in my application.
During the runing of the application i found that sometime shift register not pass the value to the case structure. at that time result is not displayed.
i have attached the application in which that problem occur and the process regarding the execution, how bug produce and how to check where the shift register stop. please find the attachment and reply on the same.
Attachments:
Shift Register Checking Application.zip ‏173 KB

I'm sorry but I don't understand your program. I only see one shift register in Result Display.vi.
What I do see is a lot of odd constuctions of while loops that only run once in your Main.VI. Also, a heavy reliance on global and local variables that I suspect are leading to race conditions.
Have you tried using the debugging tools such as probes and highlight execution to see our your application is behaving?
I'd also be concerned about how you have "Lock Front Panel Until Event Completes" in the cases of your event structure. And those event call other subVI's that may take a while to run and rely on user interaction with the front panel. I also don't understand why when I hit "OK", the subVI front panel remains open. It just makes running your application that much more confusing.

How to use documentbeforesaved method? And why my code doesn't work in template files?

Can someone help me with these two codes?
----Beginning of code 1-------------
Private WithEvents App As Word.Application
Private Sub Document_Open()
Set App = Word.Application
End Sub
Private Sub App_DocumentBeforeSave(ByVal Doc As Document, SaveAsUI As Boolean, Cancel As Boolean)
MsgBox("BeforeSave")
End Sub
--------------End of the code----------------
Beginning of code 2--------------- Code 2 is from https://msdn.microsoft.com/en-us/library/office/ff838299(v=office.15).aspx
Public WithEvents appWord as Word.Application
Private Sub appWord_DocumentBeforeSave _
(ByVal Doc As Document, _
SaveAsUI As Boolean, _
Cancel As Boolean)
Dim intResponse As Integer
Private Sub App_DocumentBeforeSave(ByVal Doc As Document, SaveAsUI As Boolean, Cancel As Boolean)
MsgBox("BeforeSave")
End Sub
In the first code, they have:
Private Sub Document_Open()
Set App = Word.Application
End Sub
I test these two codes in "This document" object, and I find out the first code works but the second code are not!
Why second code doesn't work?
Extra question: I am using microsoft 2013. I insert this code into a macro-enabled template. But when I am about to save my file I am expecting these code works. However, they didn't work!
Thank you for solving these problem for me!

Hello,
Please note that the code snippet 2 in your post is different from the code snippet in the MSDN document. Also please read the comments of the MSDN code sample:
This example prompts the user for a yes or no response before saving any document.
This code must be placed in a class module, and an instance of the class must be correctly initialized to see this example work; see
Using Events with the Application Object for directions on how to accomplish this.
Public WithEvents appWord as Word.Application
Private Sub appWord_DocumentBeforeSave _
(ByVal Doc As Document, _
SaveAsUI As Boolean, _
Cancel As Boolean)
Dim intResponse As Integer
intResponse = MsgBox("Do you really want to " _
& "save the document?", _
vbYesNo)
If intResponse = vbNo Then Cancel = True
End Sub
So the problem in your code snippet 2 is that you didn't put it into a class module and initialize the class module. If you just put it into ThisDocument, you have to initialize the word application object.
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*when we use at user -command and give smaple code fro at user-command*

Hi experts,
i am new to abap can any body tell me when we use AT USER-COMMAND and give a sample code for that.
point will be rewarded.
thanks.

Hi,
AT USER-COMMAND is a list Event.This Event is triggered when user make an action on the Application Toolber Or Menubar.
Here is the Program.
START-OF-SELECTION.
SET PF-STATUS 'TEST'.
WRITE: 'Basic list, SY-LSIND =', sy-lsind.
AT LINE-SELECTION.
WRITE: 'LINE-SELECTION, SY-LSIND =', sy-lsind.
AT USER-COMMAND.
CASE sy-ucomm.
WHEN 'TEST'.
WRITE: 'TEST, SY-LSIND =', sy-lsind.
ENDCASE.
This program uses a status TEST, defined in the Menu Painter.
Function key F5 has the function code TEST and the text Test for demo.
Function code TEST is entered in the List menu.
The function codes PICK and TEST are assigned to pushbuttons.
The user can trigger the AT USER-COMMAND event either by pressing F5 , or by choosing List -> Test for demo, or by choosing the pushbutton 'Test for demo'.The user can trigger the AT LINE-SELECTION event by selecting a line.
Hopr This Will help You.
Regards,
Sujit

HT1539 can i add my digital copy to itunes with out using the disk? my netbook does not have a disk drive and i want to add my movie to my ipod can i do it with out the use of the disk and just the code?

Can I add my digital copy movie to my iTunes with out using the disk, my gateway laptop/netbook does not have a disk drive I have the unused code and everything, I just can't stuck the movie into the computer itself and my desktop computer has no internet on it. Is there a way to add my movie to my iPod touch 2nd generation tuning 4.2.1

Hiya!
It depends on what kind of digital copy you have. This article goes ino details regarding the two types, and depending on the type you have, you may or may not need the DVD to redeem the code.
Transferring video from DVDs with iTunes digital content
http://support.apple.com/kb/HT1539
I hope this helps! Best wishes and good luck!

I need to find a more complicated example, specifically using arrays as inputs and outputs, to Code Interface Nodes.

I am a beginner in C programming and I cannot understand how to use the structures that LabVIEW creates for its arrays in C. Can anyone point me to a good example?

Check the following answer that I posted recently to a similar question.
http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=5065000000080000006D1E0000
Good luck!
Vargas
www.vartortech.com

Why is it that whenever we use Firefox Adobe Illustrator quits allowing us to use the shift, alt, and space bar features? As soon as I close Firefox, AI starts working properly again without needing to be restarted.

I go to a design school and a bunch of us have this problem. We mostly run CS4. We are also all on macs.

There is no Flash player version 15... as in your code:
<param name="swfversion" value="15.0.0.0" />
For some reason Adobe thought it would be a good idea to target a Flash player version (15) as default.....which may be out a couple years in the future. Go figure!!!
If you don't like player version 9, change to 10 or 11.... just not 15 (yet).
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Why won't my shift register work?!

I am trying to calculate the volume by multiplying the rate by the time plus the previous volume. The previous volume is the part that I can't figure out. I used a shift register and it's not working.
Attachments:
screen shot of program test 12.gif ‏13 KB

The first thing I notice is that the loop will never exit since the "Loop Done" is never being written to inside the loop. I'm not seeing what the point of the while loop is. Are you trying to wait so long until a certain volume is reached and then report it?
From a general programming view, you should breakup your code into subVIs. It'll make it a lot simpler to understand.
I'm also noticing several "multiply by 1" in there. Those do nothing, get rid of them.
I also don't see the point in having separate code for the positive and negative flow rates. The math works the same (V1 = V0 + rate). The negative will subtract on its own.
I would convert to a single flow rate. For instance, if the rate is in ml/h, convert to ml/min inside a case structure and then do the volume calculation after the case structure. If the rate is in ml/min, just pass the flow rate through the case structure and do the calculation. This will eliminate duplicate code.
There are only two ways to tell somebody thanks: Kudos and Marked Solutions
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How to run and stop LabView code without using start and stop buttons

Hey
I've attached my code that I'm going to use with thermocouples. What I'm trying to do is: when I hit start button the code should run for a minute then stop for 5 minutes and then start again, this process should be repeated twice . Could you please suggest the appropriate way to do it.
Regards
Rajab
Solved!
Go to Solution.
Attachments:
temp. samples.png ‏24 KB

Rajab84 wrote:
Hi altenbach
Thanks a lot for your help, I've tried the state machine, I’ve created 5 case structures as following: start for 1 min, stop 5 min, start again for 1 min, stop 5 min, restart again 1 min and finally stop. I’ve tried the code and it didn’t work. Could you please have a look at the attached code and let me if I need to change something. I think I’ve not used the elapsed time function properly.
Best Regards
Rajab
you really dont need to repeat cases (2x)...using a shift register will reset your timer function once the timer has reached it's set limit. the "bool crossing" is used to tell me when the "5 min" case is done and increments the cycle count....ofcoarse, change the "seconds" constant to your desired time on the elapsed timer of this example
and you could "or" the stop to the "compare = 2" or change the select "wait" to "exit" with a constant connected to the stop
Attachments:
Untitled 2.vi ‏42 KB

Any way to save data in loop without using shift register or feedback loop

Hello all
I was thinking, is it possible to save data in a loop to next iteration without the use of a shift register or a feedback loop?
I need the possibility to reload data within a loop from a lvm file, but I want to use the same data until i load some new ones.
The reason why I don't want to use the shift register or feedback node is due to speed, even though I am not sure if the shift register
actually moves all the data from one register to another, or if it is stationary until a change in the data occur.
The data I want to reuse is medium-large (6 force measurements, 2 pressure, 1 flow channels)of about 10sec data in each file with samplingsrate of 2kHz..
In my analysis program I have many CPU demanding calculations and 3D graphs, so I just want to minimize the CPU load as much as I can for each part of the
software..
I have attached a small VI to explain what I am talking about.
I now I shouldn't use the express VI, and I am going to change that as well - this is just a proof of concept!
Hope you guys can help me understand this shift register better...
Thanks!
- Tommy
Running LabVIEW 2009 32bit SP1 on Windows 7 64Bit
Solved!
Go to Solution.
Attachments:
visual.vi ‏34 KB

tombech wrote:
[...]The reason why I don't want to use the shift register or feedback node is due to speed[...]
Tommy,
shift register are the fastest you can ever get...........
Norbert
CEO: What exactly is stopping us from doing this?
Expert: Geometry
Marketing Manager: Just ignore it.

What is the maximum number of the parallel blocks or maximum pair of shift register used in FPGA VI time loop with cRIO 9104?

I am writing a FPGA VI with module cRIO 9104, I need to do a lot of parallel execution of inside a timed loop. In total, I have used 20 pairs of shift registers in the timed loop, which simply means there is 20 parallel exceution across ONE time loop. However, it tells me that there is an over-used of the FPGA resources in the compliation report. One is the Slices and the other is the number 4 of LUTS ( see the attached file), would the compile will be sucessful if I change it to ALL block diagrams cascaded in series without using any shift register accross the timed loop? And do you think that it is reaosnable to have 20 pairs of shift register arranged in parallel inside a timed loop.
Thank you!
Attachments:
afternoon912.jpg ‏2305 KB

Your compilation report has 2 useful numbers to help answer your question, I'll summarize:
Number of Slice Flip Flops = 27%
Number of 4 Input LUT's = 100% *
You are using the Timed Loop Shift registers to pass a value from one iteration of your loop to the next. The LabVIEW FPGA compiler will use Slice Flip Flops to create this behavior in the FPGA fabric. You are only using 27% of the Flip Flops, therefore the 20 Shift Registers are not your problem.
LUT's (Look Up Tables), which are the basic logic building block of an FPGA, are your problem. You are using over 100% of the LUT's in this FPGA. To fit in this FPGA you will have to reduce the amount of logic (and/or gates, additions, comparisons, etc.) in your design.
-RB

Use of shift register and similiar C code

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