Wait Until Next ms Multiple.vi explanation

altenbach,
Great examples!!!
I am using an
older code that place a “wait until next ms multiple.vi” in a time loop.
From the feedback
I am getting on the forum, I think I should use CONSUMER AND PRODUCER
ARCHITECTURE TO GATHER THE data. BUT for me to get more time for the project I would
have to explain why the current codes need to be changed.
The only thing
that change in this code when I run it at a smaller distance( angles smaller
than .72) and bigger distance (angles greater than .72 ) are the timing for the
“wait until next ms multiple.vi.” Inside
the time loop I measure the time it take for the wait until ms to finish.
I had run the
code when the angle was smaller than .72 and printed out the Boolean status for
each iteration. And when it was bigger than .72. if interested I have attached
the file. There is no different. The different is only with the timing!!!

sticyfinger wrote:
I am slow. Can you please elaborate on that some more? Sound
interesting. Think that may be related
to what happen to my code. When I measure smaller distance I have to use bigger
numbers for the wait.
Please elaborate how you are measuring. A wait controls, and does not measure, timing. What happens in the code during the wait? How do you measure?
In a nutshell, here are some semi-true analogies:
Wait until next ms multiple
Do something every hour on the hour (60 minutes multiple), i.e. wait until the minute hand points straight up. If your task takes 30 minutes, you get a 30 minute break, if the task takes 50 minutes, you can only take a 10 minute break. If your task takes 61 minutes, you get a 59 minute break, but might lose your job because you missed an assignment.
The first wait is random between 0 and 60 minutes and depends on the time you arrive at the job site.
If the wait is in a loop, the first iteration takes between 0 and x ms. All subsequent iterations are equally spaced unless your code cannot complete in the allocated time.
Wait(ms)
No matter what time it is, wait 60 minutes before continuing. This is often somewhat clouded by the parallel nature of LabVIEW. For example if a wait(ms) is in a loop, the iteration cannot complete until at least x ms have elapsed. However the timer starts in parallel with the other operation in the loop, so even if the operations take a significant amount of time, it won't artificially prolong the loop. However, if you would use a sequence such that the wait is in the last frame, the loop time will be the sum of the code time and the wait time. And so on....
All waits are the same, and independent in when you arrive at the job site.
If the wait is in a loop, all iterations will be approximately x ms unless your code cannot complete in the allocated time. Over time, there could be slight drift due to accumulations of small errors caused by the delay between the loop start and scheduling of the wait node.

Similar Messages

When the integral function is placed inside a wait until next ms multiple is it reset at the beginning of each loop?

When the integral function x(t) is placed inside a wait until next ms multiple while loop is the Integrator reset to zero every time the loop executes?

Hi,
the function works on a discrete amount of data. Hence every call to it replaces the values used first time around.
I've attached an example in LabVIEW 7.0 that uses a pulse generation vi to allow the manipulation of the array sent into the integral object, and then it's easy to calculate what the integral of the data would be.
Hope that helps
Sacha Emery
National Instruments (UK)
// it takes almost no time to rate an answer
Attachments:
integral.vi ‏39 KB

What is going on "under the hood" of the 'Wait Until Next ms Multiple' vi?

Hi,
This question is really for the developers of LabVIEW, and I don't know if they are willing to divulge what might be considered "trade secrets". Anyway, I just thought there's no harm in asking.
I use the Wait Until Next ms Multiple vi and it works great. For example, if I set my program to output a character on the serial port every 20 millisecond (mS), and check the output on an oscilloscope, I see the output at 20 +/-2 mS (that is, 18 to 22 mS). That's quite good and is all that can be expected on a PC running a non-real-time OS such as Windows.
My question is this: Since the default Windows timer has a tick rate of 15.625 (1/64th of a second) (some PC's may default to 10 mS), how does LabVIEW attain roughly 1 mS accuracy? If the same thing is coded in any .NET framework program, such as C# or Visual Basic using any of the available timers (the System.Windows.Forms timer or the .System timer), the timer interval may be set in 1 mS increments, but if you time it you will see it actually has a granularity of 15.625 mS. So instead of getting 20 mS I get 2 ticks, or about 31 mS. So I can get an output every 15.6, 31, 47, 62.5, etc. but nothing in between.
The System.Diagnostics.Stopwatch timer can be use to time code with very high resolution, or to create a high-CPU usage delay loop, but I haven't been able to find an easy way of generating an interrupt (timer tick) at say 1 mS. There are Win API functions that can set the timer to 1 mS on XP and 0.5 mS on Windows 7 and 8 Microsoft, but I have not tried them. (They come with the caveat that another program or process can come along and reset your timer!) There is the "multi-media" timer (now the HPET or High Performance Event Timer"), but it is meant for sound and video at the driver/kernel level, and not for the UI level, as LabVIEW or C# are.
So how does the 'Wait Until Next ms Multiple work? It obviously is timer interrupt-driven because it yields to other processes (which is a primary reason for putting it in your overall While loop). And is it guaranteed on all recent OS versions (mine was timed on an dual core XP OS)?
Thanks for any insight.
Your typical curious engineer,
Ed

Ian,
Thanks for your reply. Yes, I'm sure LabVIEW uses the (default) Windows timer. And yes, 1 mS is not guaranteed due to the preemptive nature of Windows (and even "RTOSs" to varying degrees), which is why I see about plus or minus 2 mS.
Apparently the Windows timer can be set by API calls. See: http://www.lucashale.com/timer-resolution/. Here's a screen shot of his TimerResolution.exe on a Windows 7 PC:
Here it is on my Windows XP PC after I set it to "Maximum" (initially it was 15.625 mS):
Notice that it sets the Maximum to less than 1 mS, which is supposed to be the max, so there are some bugs. Plus the Default button does not reset it in XP, but does work on Windows 7 or 8. (I know this is not the place to "debug" non-LabVIEW applications!)
I'll bet LabVIEW sets it, too. The only caveat, as I said, is it looks like another application can change it, since the hardware timer is a "global" timer. I have not seen this issue in my LabVIEW applications, have you?
I guess I need to do some more digging to see the code to set the timer, but it looks like the developers of LabVIEW have it figured it out.
(FYI, I did notice that running my LabVIEW app (which gives about 2 mS resolution) or a C# app, which gives 15.625 mS resolution, does not affect what TimerResolution.exe reports, so I'm not sure if it's really working correctly. If I figure it out I'll post the results.)
Ed

Help with "Wait Until Next Millilsecond Multiple" vi

Hello,
      I'll try to keep this brief and follow up with additional information when necessary. I'm not using the current software so PLEASE let me know if this has been resolved with the newest version. I do plan to upgrade but not this month.
      The vi "Wait Until Next Millilsecond Multiple" isn't working as I expect. Today, if I subtract the millisecond timer value from the real time, I get 10/19/2006 15:13:21.33 (try this yourself - current time -millisecond timer value/1000 = timer origination time). The millisecond timer value output is counting up from there. Since it doesn't originate from an expected predictable time (appears arbitrary). I can't use the vi AS-IS and get my vi to repeat at a predictable interval. If I use 1000 for the input, I expect the timer to end at every whole second in time. However, it ends at about 0.33 seconds later. If I use 60,000 for the input, I expect the timer to end at every whole minute in time. However, it ends at 21.33 seconds after the whole minute mark. My timer appears to be losing time but I can confirm that tomorrow by comparing data. I could create a vi to do the same function but I would like to know if there is a fix for this first.
      I have a running vi to back this up and I will post that and other examples if necessary.
Please Advise, Scott

Hello,
      My mistake. The vi was intended this way. When I read the help information on "Wait Until Next Millilsecond Multiple" it did NOT include the information about the "Tick Count (ms)" because I don't really use it. It states "Returns the value of the millisecond timer. The base reference time (millisecond zero) is undefined. That is, you cannot convert millisecond timer value to a real-world time or date. Be careful when you use this function in comparisons because the value of the millisecond timer wraps from (2ˆ32)–1 to 0."
      So there's no bug here but I do believe that there should be a similar function that would generate the millisecond multiple to be a multiple of real time. So, if you input 60,000 the timer would end at the end of every minute. I really don't see why the base reference time is undefined. LabView can give me the real time. I would guess that LabView could restart the millisecond timer at the start of every day. This would certainly add value to the vi.
      I do want to mention that I've read other threads where people believe that the millisecond timer value is based on real time and they have inadvertantly advised others accordingly.
      I'll just make my own function for now. I'll just use "Get Date/Time in Seconds", calculate the time to wait from the multiple, and divide it into 100 pieces or more (depending on resolution desired) and loop that many times or until the desired time has passed (rechecking time at each loop).
Thanks, Scott

Wait until next ms multiple

Hallo,
ich möchte gerne wissen, was "wait until next ms multiple" in Betriebsystem basierte. ich meine, wenn ich die Zähler 100ms einstelle, dann wird meine Simulation wirklich jede 100ms durchgeführt, oder es hängt von der BS ab?
Können Sie mir ein Beispiel geben?
mfG
Hakan

Hakan,
"wait until next multiple (ms)" is a vi which is normally used in
loops. i these structures, this vi is the last one to be called. it
defines, how much time passed from start till now and waits until the
next (integer) multiple of the time connected to it. lets make an
example:
preloop-code 50 ms, loopcode 10 ms, time connected to the vi: 100 ms.
1st iteration: preloop 50 + loop 10 = 60 ms already passed when the vi
is called. so the vi waits another 40 ms to make the 100 ms full.
2nd and following iterations: loop 10 ms, so the vi waits 90 ms.
if the time would have been 80 ms preloop and 30 ms loop, the 1st
iteration would have waited 90 ms, so the time would have been overall
200 ms. (2*100ms).
Do not make the mistake to take this vi as a substitute for
hardwaretiming, since every OS except dedicated realtime-systems (linux
for itself is not a realtime-os!) has a jitter depending on the
systemload and running services!
"wait until next multiple (ms)" ist ein vi, das gewöhnlich in schleifen
verwendet wird. in diesen strukturen wird es als letze funktion
aufgerufen. es ermittelt, wieviel zeit von beginn bis zum aufruf
vergangen ist und wartet bis zum nächsten ganzzahligen vielfachen der
angeschlossen zeit. betrachten wir ein beispiel:
prelloop 50 ms, loop 10ms, angeschlossene zeit an dem vi: 100 ms.
erster durchlauf: preloop 50 + loop 10 = 60 ms sind bis zum aufruf des
vis vergangen. es wartet also 40ms um die 100 ms voll zu machen.
zweiter und folgende durchläufe: loop 10 MS, also wartet das vi 90 ms.
wäre die preloop-zeit 80 ms und die loop 30 ms gewesen, so hätte das vi
im ersten durchlauf 90 ms gewartet um die 200 ms voll zu machen.
machen sie aber nicht den fehler, dieses vi als ersatz für ein
hardware-timing zu verwenden; jedes betriebssytem außer echte
"echtzeitbetriebssysteme" (linux von sich aus ist KEIN echtzeitsystem!)
erzeugt einen "jitter"(zeitversatz), abhängig von der auslastung und
der anzahl der laufenden systemdienste!
Norbert B.
NI - Germany
CEO: What exactly is stopping us from doing this?
Expert: Geometry
Marketing Manager: Just ignore it.

Question about the Wait Until Next ms Function

Hello,
I met a problem when I tried to use wait until next ms function to control the period of the loop.
I use Labview2009 now. I wrote a VI to sample the current values at 100Hz and then store the samples in a text file. The currents are sampled once in a loop and then wait for next 10ms to begin the next loop. After 360,000 loops (should be an hour), it will creat a new file to store the new samples in the following an hour.
I left the VI runs on CompactRio for the whole weekend. The result I got is shown in the picture below:
24 files should be created in one day. While there were only 3 files created in the firest 24 hours ( from Fri 16:00 - Sat 16:00). And after that it worked very well.
When I checked the first three files (created from Fri 16:00 - Sat 16:00), I found that it didn't sample at 10Hz. It sampled at the frequency of about 20Hz (sometimes 18Hz, sometimes 19Hz).
I am confused by the problem a lot. What may cause it didn't work in the first 24 hours and worked after 24 hours? And How could I fix this problem?
Thank you very much!

You need to show us some code!
This cannot happen in a single loop, but can easily happen if you have e.g. stacked loops or sequences containing multiple wait statements.
Also have a look at these old threads:
Synchronization problems during measurements (using while loop)
accurate timing between events
If accurate timing is important, use a timed loop. Your incorrect times are faster, so I don't think there is a problem with the inner code taking too long.
LabVIEW Champion . Do more with less code and in less time .

In our program, we are concerned about reducing CPU work; how to wait until a boolean condition changes in a "while loop"?

Is there a way to wait until a boolean condition changes (instruction is sent) in a "while loop" (because I want the program run until I press exit button)? Now it is consuming a lot of CPU because it is running the loop very fast waiting for instructions unless I stop the program.
Thank you.

Use /functions/time and dialog/wait until next millisecond multiple in the
loop. Input 100ms.
"mcdesm" wrote in message
news:[email protected]..
> In our program, we are concerned about reducing CPU work; how to wait
> until a boolean condition changes in a "while loop"?
>
> Is there a way to wait until a boolean condition changes (instruction
> is sent) in a "while loop" (because I want the program run until I
> press exit button)? Now it is consuming a lot of CPU because it is
> running the loop very fast waiting for instructions unless I stop the
> program.
>
> Thank you.

Should i upgrade from early 2008 macbook pro or wait until 2015?

Hi,
I'm debating on whether to bite the bullet now and buy the new macbook pro (15 inch) or wait until next year. i know this is practically obsolete in Apple years, but it actually still runs ok for my purposes (not used for work). I added RAM to 6 and am currently running Yosemite. I've read that many people keep their original macs for years. Advice helpful. Thanks!

Do you NEED new computer for any particular reason or is this just a "Want"?
If you need a new computer NOW then buy one. If not then wait.

LV PDA 8 wait for ms and wait for next N ms multiple costs extrem performance.

Dear LV PDA users.
There is another bug using the PDA toolkit.
The usage of wait for ms and wait for next N ms multiple costs me 200ms while the input is 1ms.
I have tried it without the wait functions and the looptiming was 0..1ms.
One possible workaround is to use timout events with while loops.
This works fine without delays.
With kind regards
Martin Kunze
KDI Digital Instrumentation.com
e-mail: [email protected]
Tel: +49 (0)441 9490852

This issue has already been reported to the R&D group at NI (at least that is what I'm told) ... refer to this thread ... Here

Measure time of an measurement and if measurement time is less than 90 second wait until 90 second and then proceed to next steps or stop.

Hi
I am trying to make a program
      During execute a measurement count the time.
      If measurement time is more than 90 second proceed to the next steps (or stop the measurement)
      If measurement time is less than 90 second, wait until 90 second and then proceed to next steps or stop
I appreciate deeply if some help me.

What sort of measurement are you talking about? What affects the time of your measurement? The very basic description you have is of a state machine and there are numerous examples of that
1. Actually I would like measure the time of "Alignment" function done by wafer test equipment name Prober ( the model is "UF3000" made by TOKYO SEIMITSU CO., LTD.
2.. Right now the "Alignment" function is started when a GPIB command is written as "N" and wait for resposne 70 in polling.
Please refer to the attachment for Alignement function if it help you.
In the attahement
For Alignment error delay we are using =600
Alignment counter =30000
align loop cnt = 30000
This is a program wriiten by another person and he is not availabe any more. What I am trying to do is
1. During execute a "Alignment " function count the time.
2. If  "Alignment " function time is more than 90 second proceed to the next steps
3. If "Alignment " function is less than 90 second, wait until 90 second and then proceed to next steps
Attachments:
Alignment function.xlsx ‏153 KB

Not sure whether to wait until I get my new mac notebook...

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This will not prevent you from syncing your iPad with your new Mac. An iPod Touch, iPhone, and iPad are not formatted for a Mac or PC.
In regards to iTunes content, an iPad can be synced with an iTunes library on a single computer only and photos can be transferred from a single computer only. When transferring iTunes content and photos from another computer, all iTunes content and photos transferred from a different computer will be erased from your iPad first.
You can sync contacts, calendar events, notes, and Safari bookmarks with the supported applications on multiple computers - between two Macs, between two PCs, or between a Mac and a PC.
When your get your Mac, you will want to transfer select data from your PC to your Mac that you will need or want to access on your Mac such as documents, photos, and your iTunes library. If your PC is a laptop or notebook, an Apple store can help you with transferring this data from your PC to your Mac.

Wait for Next Sample Clock error, or 'How do I put this VI on a diet'?

Hello!
In the attached VI I've been running since June, I have all the functionality I need. No questions there at all, thanks to much time and help from this board!
My nagging problem is that any time I use the PC for other minor tasks other than Labview, it will display the following error:
209802 occurred at DAQmx Wait For Next Sample Clock.vi:1
A search earlier in the month indicated that it could have been a result of my old and outdated PC; I've since replaced it with a brand-new dell dimension 1100. Celeron 2.53ghz with 1.00gb of ram. Should be enough to service Labview and other minor tasks (automatic antivirus updating and also maintenance tasks). However, any time any other program opens or even if the screen is scrolled around on Labview quickly, I get that same error.
Resource usage when idle, with nothing but this VI running is 5-10%, all labview. Upon scrolling the VI, it quickly jumps to the 58-60% and above mark and soon throws that error.
I know that there's a lot of code here that can be cleaner--I know that even though it's functioning correctly, there could be a less resource-hogging way to go about it. Can anyone give me any suggestions on how to make this VI a little 'lighter'?
Thanks so much in advance,
Ralph
Still confused after 8 years.
Attachments:
Currently Running 063006.vi ‏899 KB

Hi Ralph,
The wait.vi waits until the amount of time has passed. While the wait on next ms.vi uses some kind of quotient and remainder on the computer time until the remainder passed zero.
In this way you can synchronize 2 loops, and somehow it is less time-consuming. The only difference you will see is in the first run!
There you see a smaller amount of time:
Message Edited by TonP on 10-04-2006 04:21 PM
Free Code Capture Tool! Version 2.1.3 with comments, web-upload, back-save and snippets!
Nederlandse LabVIEW user groep www.lvug.nl
My LabVIEW Ideas
LabVIEW, programming like it should be!
Attachments:
Example_BD.png ‏2 KB

I the cloud and itunes match. Some songs have the "waiting" icon next to them but are unable to upload and instead of determing them ineligible itunes continues to try to upload that song and never gets to the rest of the list.

I have icloud and itunes match and most of my songs have been uploaded to the cloud. Some songs still have the "waiting" icon next to them and when I turn itunes match on they neither upload nor are they determined ineligible. My computer will literally spin its wheels for hours trying to upload the same song. Additionally, I uploaded an audiobook disc on my computer and 3 of the 11 tracks are still waiting to be uploaded???

The exclamation mark happens if the file is no longer where iTunes expects to find it. Possible causes are that you or some third party tool has moved, renamed or deleted the file, or that the drive it lives on has had a change of drive letter. It is also possible that iTunes has changed from expecting the files to be in the pre-iTunes 9 layout to post-iTunes 9 layout,or vice-versa, and so is looking in slightly the wrong place.
Select a track with an exclamation mark, use Ctrl-I to get info, then cancel when asked to try to locate the track. Look on the summary tab for the location that iTunes thinks the file should be. Now take a look around your hard drive(s). Hopefully you can locate the track in question. If a section of your library has simply been moved, or a drive letter has changed, it should be possible to reverse the actions.
Alternatively, as long as you can find a location holding the missing files, then you should be able to use my FindTracks script to reconnect them to iTunes .
If the missing files just can't be found then, assuming you are in region where you are permitted multiple downloads of your audio purchases, delete the current enties and download again from your purchased history.
tt2

No more than 1 sessions at a time are allowed. Please wait until open sessions expire.

I have been unable to log into my Actiontec MI424WR router this week, The router returns the message "No more than 1 sessions at a time are allowed. Please wait until open sessions expire." every time I try to log in. This has been going on for days. Even pulling the power to reboot it did no change. I'm the only user in the household that would log into it, so I don't understand how this could occur. How can I get in?
GLN2

I really don't want to do a hard reset as I have a handful of custon port forwarding rules that I had created. I'm not a wiz at that, so it would take me too much time to re-create! I may have no choice. Next time I can get in I will try the backup of the config file. I hope it contains the port forwarding rules.
The backup function should work fine, I have used it to save my Steam port forward rules to my hard drive, after a pin hole reset I was able to restore successfully. I did configure mine to 1 session & ALWAYS logout when I am done. I have never had any problems logging into the router. But in your case you may need more than 1 session allowed.
Are you using a native or 3rd party app to remember your router ID/password? IF you are do not do this, you are "defeating" the built in security of the router
If a forum member gives an answer you like, please give them the Kudos they deserve. If a member gives you the answer to your question, mark the answer as Accepted Solution so others can see the solution to the problem. Thanks !!!
http://forums.verizon.com/t5/Verizon-net-Email/Fix-for-Missing-Inbox-sent-folders-etc-with-Internet-Explorer-11/m-p/647399

Buy new Macbook Pro now or wait until 2015

Hi!
I'm currently trying to decide between buying a new Macbook Pro 15" right now, or waiting for any possible releases next year.
I'm totally dependent upon my laptop for both school and work. I heavily use programs such as Photoshop, Xcode, and others on an everyday basis. My current laptop is a summer '09 unibody Macbook Pro 13" (the cheapest version), with upgraded aftermarket storage and ram (two years ago). It works surprisingly well, and I could probably go on living perfectly fine with it. However, I find myself every day swearing over how annoyed I am by it. I often resort to turning it off and back on due to it freezing or lagging. But by all means, I can live with it.
I was planning on buying a new Mac last winter, but I decided to wait for a possible upgrade this summer (2014). But when that was released I couldn't buy it until September because I was abroad. When I finally got back, I reluctantly decided to wait for a larger upgrade this October (heard something about Broadwell processors), but that didn't come.
I figured since I waited that long, I might as well just wait a bit longer (until January). However yesterday my charger stopped working (Apple gave me a new one free of charge), and I realized how fragile and old my laptop is. I better trade it in before anything serious goes wrong.
So now I'm trying to decided whether I should wait for a possible upgrade or buy a new one now. I don't think whatever upgrade is coming will be large enough for it to be worth it, but I just don't wanna splurge $2500 on a new mcbp if it's gonna be outdated soon. When I'm buying something I like it to be just after it was released, to avoid situations where I'm left with a brand new outdated product.
I'm scared that if I buy it now I will regret it if a new version comes out soon. However, I'm scared that if I don't buy it now I'll end up waiting indefinitely (or just until next summer).
It'd be stupid of me to waste time now using my old Mac when I'm clearly in need of a new one. But again, I wouldn't be able to live with myself if they release a new major update in early 2015.
So hopefully someone understands my problem. My question is: what do you guys think is the right thing to do? What updates can we expect to see to the Macbook Pro line, and when can we expect to see them? Are we talking about minor upgrades like this past summer, or are we talking massive design changes, lighter and thinner body, better screen and performance? And would we see this in early (Q1, Q2) 2015 or as late as 2016? I know you can't give any definite answers, but at least you can make better assumptions than me haha.
Thanks!

We don't know. We have no more insight into Apple's plans for 2015 than you do. Making your decisions for you is not the purpose of these forums, so please do your own research and make your own decisions. If you have a technical problem with an Apple product then that is a proper use of these forums.
Apple Support Communities - Terms of Use

Wait Until Next ms Multiple.vi explanation

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