Time in while loop measure

hello,
I want to measure the time in a While loop.
I'm trying to know, how much does need my while-loop to run for i = 0 and for i = 1. Which Function can I used?
BR..

You can use the Tick Count function. It gives you the clock time in milliseconds. Compare it with the value from the previous iteration that you store in a shift register.

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Program times out while looping at internal table with huge records - Needs fine tuning suggestions

Hi,
I am trying to execute a report. It times out while looping at vbap internal table. This internal table has 140000 records and does the validation within this loop and geenrates data for the output. Due to this huge volume, the program times out when executed foreground.
There are no nested loops, so I cannot apply 'Parallel Cursor' here.
Is there any way I can fine tune the program so that it doesn't timeout? Is it possible to apply 'Parallel Processing' . If yes, how?
Thanks,
Pavan

Hi Pavan ,
              ->sort your internal table by all primary key for vbap.
              ->Read a Record from the table (use your condition here)
              ->if record satisfys your where condition ,get that record index .
              ->loop the table from the index (without condition) .
              its like parallel cursor only but for single loop .;-)
              ->use field symbols ,wherever possible .
           if still dump is coming ,contact your basis team .
regards,
Krishna.

Execution time for while-loops?

Hi,
How can I measure the time used during one iteration in a while-loop?
Dennis

Prior to the loop get the time. Initialize a shift register in the loop with that time. Now - at the end of the code in the while loop get the time once again, and find the difference between the value in the shift register and the new time. Wire the new time to the right hand shift register terminal...when you loop the difference will now tell how long each iteration takes.
In the attached example I have usied the get ms timer value to get the current time. The ms timer loops though so there is a possibility that it will give an incorrect value just when it resets...normally that's not a big problem, unless you want to do something critical based on the loop time...
In the example the loop code is just an add operation and a wait until next multiple (to
make the loop use some time), you can remove all that and put in your own code, or better - just add the timer code to your own loop.
PS. The example illustrates one thing about the wait next ms function that people sometimes overlook; the first time it is run it does not have a start value to relate to so it won't wait the specified number of ms on the first iteration.
MTO
Attachments:
TimeTheLoop.vi ‏21 KB

Wait time in while loop: wait before all other code in the loop runs

My vi is attached.
In the 'Check for Equilib' case, there is a while loop that takes data from a pressure gauge and compares it against data taken equilibTime seconds previous. equilibTime is hooked up to a wait(ms) function inside the while loop. Currently it appears that the code in the loop runs, and then the loop waits so many seconds before the next iteration. I would like to reverse this process, i.e. in each iteration, the loop will wait so many seconds and then run the rest of the code in the loop. I want to do this because I don't want there to be any delay between then time the 'check for equilib' code finishes and the start of the 'add shot' case.
Can anybody suggest an elegant way of implementing this?
Thank you
Attachments:
Take Isotherm.vi ‏294 KB

No. Use Flat sequences they are far preferable to stacked sequences. Functionally they are the same. But a flat sequence is easier to read, doesn't hide code, and you don't have to worry about backwards wiring caused by sequence locals in stacked sequence.
Note, you have two oddities in your lower while loop.
1. Write a value to an indicator's terminal node and to a local variable of the same indicator is pointless. They do the same thing.
2. Reading from a local variable of an indicator and writing to its terminal node is just as pointless, as you aren't doing anything.
In your middle loop "Add shot" case, you have the local variable of DC estimate righting to a right hand side shift register, but you never use the left hand shift register. So you are saving that value for future loop iterations, but never use it.

Capturing of time taken by a while loop in bpm

Hi ,
I have a busniess process ,and my receive step is defined in a while loop.
so it starts with a while loop.
I want to keep a condition on the while loop that it should receive the messages only for a period of 1 hour ,and if it exceeds this period it should end up the process triggeringa mail.
I mean to say if there are 12 records to be processed through the while loop ...and if I receive only 11 records ..it will be waiting for that final record in an infinite loop ..so I dont want that ...instead if the total no of records are reached then it should move forward ..If it is waiting for the missing records for an hour ..I should stop the process and trigger a mail to the queue monitor saying that record is missing...I have finished the process without this processing time condition successfully..
I am new to XI and I dont have any idea on how to capture this processing time of while loop.
can some one please help me out in this issue...
Thank you in advance...

Hi Latika,
Yeah I understand we can go with fork but why I am going with this is ,I have already designed a Payload dependent loop ,by using while loop.so it makes my job simple ...
Now I am converting it to time dependent loop,so only the final question I have is...In the time dependent loop documentation ..they have taken it as infinite loop and only kept the time limit in the deadline branch...so when the deadline reaches they trigger something.
If you go to the documentation of time dependent loop(http://help.sap.com/saphelp_erp2005vp/helpdata/en/08/16163ff8519a06e10000000a114084/content.htm) ..they took the infinite loop...in this loop if I mention the counter ..and if this record count triggers before the time limit...it should come out of the block...would it work this way ?
Thanks a lot...

How do i stop a while loop

I'm new to labview and I'm having a problem stopping a while loop (running windows XP/2000 with the student edition of labview express 7).
I'm doing a data acquisition program where I'm constantly reading in voltage and comparing it to a set point value, when the input voltage goes above the set point, i want the while loop to stop. How do I do this? I already have an LED going on when the criteria is met, but I'm not sure how to actually stop the loop (i.e. change the iteration value from true to false-i guess). If anyone can please assist me with this I would very much appreciate it.
I've included my program too.
Attachments:
CO_Detection_Monitoring_System_Modified.vi ‏60 KB

Hello Everyone-
I've just posted a message about stopping a while loop and it was answered accurately and quickly- thanks to LV_Pro and PauloM- thanks much- its nice too see that there are many helpful people out there! Unfortunately, I have 2 more questions to ask of the forum.
My application is almost completed- I just need to add an elapsed time counter that will tell me how long it took for my LED to trigger (from my set point-i.e. when from 0:00:00 until when my loop stopped).
Now I've found a perfect elapsed time counter on the NI web site contributed from Mike Hall from Ohmeda Medical- the page is here.... http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=D37E2493DC333076E034080020E74861&p_node=DZ52032&p_source=external
So my first question is, it looks like I can just extend the while loop box in my 'CO detector... .vi' and paste just the code from the 'elapsed time.vi' while loop into my loop and I will be set- but do I need to change my wait until next multiple to be a 1000 too in my program? Probably, but I'm not sure hence the question- or other ideas would appreciated.
My second question is now that my application is complete (after I add the elapsed time above), I need to exactly duplicate this process for 7 other DAQ inputs (i.e. right now I'm using only 1 of 8 analog inputs on the FP-AI110). So should I make my 'CO detector.. .vi' a separate program (I remember reading something about this in one of the posts earlier).
Any help is very appreciated.
Thank you again,
Daniel
Attachments:
CO_Detection_Monitoring_System_Modified.vi ‏60 KB

Ai read in while loop

I am acquiring data from a DAQ e series card. i intialized the daq by using AI config out side while loop . i used AI start and AI read in while loop . iam acquiring data from 5 channels. the buffer size ia 1000 and so is the scan rate in AI start.I want to save the acquired data in the file. i am also displaying data o n chart. every thing is working fine. my problem is i want to save 500 points in one seconds. for this i changed the while loop execution time by using waint until multiple sec VI and assign it 10 i was expecting that now iwll save more data point in file as now loop will execute more fast but it does not happen like this. is there any way to minimize the executing time of whil loop.i checked if i deleted AI start and AI read then loop execute very very quickly. should i place AI start and AI read out side loop but then how will it acquire data contiously. I m attaching gif file of the protion of my VI .any suggestion?
Attachments:
myVi.GIF ‏72 KB

I was working quickly, and from memory, so my apologies for errors or non-clarity in my previous post. :-(
The AI START VI, should be used OUTSIDE the loop, since you only want to START the task ONCE.
When the task is complete (your WHILE loop is done), then call the AI CLEAR task to clean up (ONCE).
If you set the NUMBER OF SCANS TO ACQUIRE input to AI START to zero, that has a special meaning: acquire data indefinitely. It will not stop on it's own (assuming no errors occur), you have to explicitly stop it.
If you do this, you have to read the data often enough to avoid buffer overflow, which means the incoming data is filling up the buffer faster than you're emptying it.
I have attached a picture of the general idea. If you really want to use the CPU efficiently, then consider the shift-register idea in the picture - you process on batch of data WHILE the next batch is coming in. If you want a simpler solution, forget the shift-reg, and process it directly after reading it. If your buffer is twice the size of your processing size, you'll be OK.
Message Edited by CoastalMaineBird on 09-14-2005 07:45 PM
Steve Bird
Culverson Software - Elegant software that is a pleasure to use.
Culverson.com
Blog for (mostly LabVIEW) programmers: Tips And Tricks
Attachments:
DAQExample.png ‏16 KB

What is the best way for writing cursors in while loops

i just chage my flatform from visual foxpro to sql
for every report part using query analyser i have to make report on any tables
suppose : - mastempno wise report
so i heve to use cursor or store procedure in while loop
for searching in transaction table
so sometime i get confunsion of using cursors two times in while loop for fetching the values
so help me for writing some simple codes for using cusrors in while loop while can fetch all values in transaction table

Is this what u r looking for
A Simple Cursor Example Which gives all records
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Timing with while loop

Hello,
How can I do a time with while loop?. I want to read a data in the While- Loop for 1 sec and then go to B .. I added a pic,
Attachments:
while- loop.GIF ‏6 KB

nichts wrote:
Hello,
How can I do a time with while loop?. I want to read a data in the While- Loop for 1 sec and then go to B .. I added a pic,
I would use as GerdW has mentioned,"elapsed time.vi" in a statement 1st case structure, after set time has elapsed> goto 2nd case structure. try not to use flat sequences....this can be done with case statements with transitional coding. I have noticed young LV programmers like to use flat sequences...I think it's a trap set up by LV developers?

Stop a while loop with a interrupt

I' m using a while with a delay time of 60 seconds to perform a sub vi.
So when I press the stop button it could take in extrem 2 minutes to stop the vi. I want to use something like an interrupt or jump order to stop the vi without waiting for the end of delay time.
How can I create an interrupt in lab view 6.1.
Thanks for help. bye uli

If the delay is in the calling VI using Wait (mS), you can run a smaller delay multiple times (a while loop inside your main while loop), checking Stop between each of the smaller delays until the smaller delays add up to your bigger delay. See the attached DelayWithStopCheck.vi.
But this technique doesn't stop the sub-VI: it just stops the loop in the main VI which will still run until the sub-VI is done. You could connect the Stop button to a global which the sub-VI checks in a loop to know if the calling VI pressed Stop.
Attachments:
DelayWithStopCheck.VI ‏41 KB

Time Measurement in a While-Loop

Greetings gentleman;
I am a little bit new at Labview, and though i searched for an answer without posting, i was not able to find one.
So here is my question, i would like to know how can i measure time of a loop sequence, in other words, how much time does my VI take to execute the whole main loop ?.
A little explanation, the attached VI tries to be a Markov Chain, it takes some values in the first case structure depending of the previus loop, then, if the values are correct, it goes to the next step and so on. It is quite simple, yet, my issue lies with the time measurement. Since this is a probability "distribution" it could take infinite time to execute one single loop if it does not meet the requierements, but is programmed to meet them so an average timing should work.
So, if you look at the While loop, the big one, that i would like to measure how much time does it take to do one round.
Thanks for the help, i would be glad to read some ideas on how to measure that.
Kind regards,
Stgo.
Solved!
Go to Solution.
Attachments:
Markov Chain.vi ‏30 KB

You can find a few examples in the NI Example Finder by searching for 'speed test' or 'benchmark'.
Essentially, you create a flat sequence structure inside your while loop. In the first frame, you measure the current tick count. In the middle frame, you run your code. In the final frame, you measure the tick count again, and subtract the first count from this. This gives you the execution time to run the code.
You can see a community page on it here.
There's a high resolution tick/time count VI hanging around somewhere which is excellent for benchmarking and improving efficiency, used in place of the Tick Count (ms) primitive.
Edit - remembered where it was
https://decibel.ni.com/content/blogs/EvanP/2010/10/04/tick-count-us--microsecond-timing-granularity-...
CLD

Why writes LabVIEW only every 2 seconds the measured Value to a Excel (In a while loop with 100 ms tact)?

Hi everybody,
I use the myDAQ to measure speed, ampere, and voltage of a battery driven motor. (For Current measurement, i use a Sensor which outputs a 0-10 V signal). I placed all DAQ-Assitants in a while loop with a [Wait until next ms multiple] clock and set a value of 100 ms. I thougt, Labview will now write into my text file 10 times a second all values. In fact, as you can see in the attached text file, Labview only writes in a unsteady interval of 1-2 seconds a value, which is too less.
The question: Did I do anything wrong, how can you create VI that writes you lets say 10 values a second into text file? Or is simply the DigitalMultimeter input of the myDAQ not able to sample a rate of 10 Hz? I couldn´t find any information in the specification handbook about the sample rate of the DMM?
If anyone can help me would be great! Thanx a lot, Markus
Attachments:
Measure Speed+Current+Voltage into Excel.vi ‏175 KB
Test7.txt ‏1 KB

File I/O is not very efficient. I recommend that you do you file logging in a parallel task. Have one task do your data acquision. This task would then pass the data to be logged to the logging task via a queue. That way your file operations do not impact your data acquision. Also, express VIs are not very efficient. You would be better off accessing that directly using the DAQ VIs. The express VIs contain lots of steps that do not need to be done every time you call it such as initializing the device.
Mark Yedinak
"Does anyone know where the love of God goes when the waves turn the minutes to hours?"
Wreck of the Edmund Fitzgerald - Gordon Lightfoot

How can I build a table with the time values of a timer from a while loop

Hi:
I have a question concerning building a table:
Every 100ms I read a value from a sensor (while loop with a timer). I would like to build a table with the actual time and the concerning value. For example:
0msec         1V
100msec     2V
200msec     3V
300msec     4V
etc.
If I use the Express VI for building a table, I always get the date and time, but I don't need the date and the time is in the following format: HH:MMS, which is nonsensical for me as I can't differentiate within msec. Can I change the format anywhere?
Can I also save the table to a file or even to an Excelsheet? How can I do that?
Thanks for your help!

Hi Craig:
thank you very much. To solve the mystery : ) :
I want to drive a stepper motor with a specific frequency. To get the current degree value of the motor I would like to measure the current time (from the beginning of the move on). (With a formula I get the degree value out of the time)
Concurrently I would like to get data from a torque sensor and from a pressure sensor. That's why I asked you about the time and the table. The measurement should start with the movement of the motor. How can I do that? Right now I have different block diagrams (different while loops) (see attachment) and I would like to put them in one.
I haven't done the block diagram for the pressure sensor yet, so there is only the one for the torque sensor and the one for the motor.
I also would like to set a mark in the table when the voltage value of an analog input gets under a specific threshold value. Is that possible?
I'm sorry, I'm a novice in LabVIEW. But maybe you can help me.
Thank you very much!
Steffi
Attachments:
motor.vi ‏238 KB
sensor.vi ‏59 KB

Use the LabView time delay in a while loop instead of using the instrument inherent time loop.

I have a zes lmg500 that I use. It has the option of continues measuring data, with a user control cycle loop (still using a while loop but the delay is coming from the instrument). The problem is that the loop time is not constant. Can I use a very short time (100ms) as the instrument cycle time but use a longer time delay in the while loop that collect the data?
I know many instrument offer the same abilities, so the question is relevant to all of them.
Thanks for any help
Solved!
Go to Solution.

Does that measurement VI have built-in wait functionality and a timeout?
If not, then you are simply polling the VI at 1 kHz, but I suspect that this is not the case or your Waveform Chart probably wouldn't look as you expect (getting 0's put in everytime measurement data is not available).
I expect that if you have the instrument set up to send data at a fixed time interval (i.e. 100 ms), all the data that it is sending you will end up residing in your serial buffer (or the instrument driver will have taken it out and put it in another internal buffer), so if you come back to read it 1 sec later, then you will have 10 data points to go through. Whether you can read them all at once with the read VI or have to call it a whole bunch of times until empty I can't say.
What is your objective?

Sir i am using datasocket read ,i am communicating with java but my problem is that bcz im using while loop to see if value has changed my labview consumes all the processors time ,sir i want a event like thing so that while loop is not in continuous loop

sir i have given lot of effort but i am not able to solve my problem either with notifiers or with occurence fn,probably i do not know how to use these synchronisation tools.

sir i am using datasocket read ,i am communicating with java but my problem is that bcz im using while loop to see if value has changed my labview consumes all the processors time ,sir i want a event like thing so that while loop is not in continuous loopHi Sam,
I want to pass along a couple of tips that will get you more and better response on this list.
1) There is an un-written rule that says more "stars" is better than just one star. Giving a one star rating will probably eliminate that responder from individuals that are willing to anser your question.
2) If someone gives you an answer that meets your needs, reply to that answer and say that it worked.
3) If someone suggests that you look at an example, DO IT! LV comes with a wonderful set of examples that demonstate almost all of the core functionality of LV. Familiarity with all of the LV examples will get you through about 80% of the Certified LabVIEW Developer exam.
4) If you have a question first search the examples for something tha
t may help you. If you can not find an example that is exactly what you want, find one that is close and post a question along the lines of "I want to do something similar to example X, how can I modify it to do Y".
5) Some of the greatest LabVIEW minds offer there services and advice for free on this exchange. If you treat them good, they can get you through almost every challenge that can be encountered in LV.
6) If English is not your native language, post your question in the language you favor. There is probably someone around that can help. "We're big, we're bad, we're international!"
Trying to help,
Welcome to the forum!
Ben
Ben Rayner
I am currently active on.. MainStream Preppers
Rayner's Ridge is under construction

Time in while loop measure

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