Tick count

Hi. Can I ask how do you make the tick count reset when you start the program .
Thanks in advance!

You can't. It is based on the PC clock, It starts at zero when the PC starts.
You can take the reading at the beginning of your VI and subtract it from later tick counts.

Similar Messages

Stopping a while loop using the time difference of two tick counts

Hi Guys,
I'm currently writing a code which test how long does it take for a formula node to perform its operation. The program uses a while loop to perform the calculation, and the program stops after calculating when tick count has reached 10 seconds. The program then displays the number of iterations it does in 10 seconds.
So initially I created 2 frames of sequence structure. In my first frame I have my initial tick count, and in my second frame I have my final tick count and the while loop. I used the subtract function and divide the output by 1000 to get the time difference. Then using the comparison function, I set if output > 10 then the program should stop, to do this I linked the output of the comparison function to the stop button inside the while loop.
However, when I tried to run the code, the program just didn't run. Hence I created a similar program which puts the last tick count in new frame sequence. When I ran this code, the program never stopped.
Do you guys have any idea what went wrong with my codes.
Thank you!
Erry
Solved!
Go to Solution.
Attachments:
1. Tick Count.vi ‏27 KB
tickcoun2.vi ‏27 KB

Dataflow!
In both VI's the stop terminal of the while loop is controlled by a boolean whose source is ouside of the while loop. So that loop will either run once, or run forever, depending on the value of the boolean that is calculated before the loop starts and shows up at the tunnel going into the loop.
I would recommend looking at the online LabVIEW tutorials
LabVIEW Introduction Course - Three Hours
LabVIEW Introduction Course - Six Hours

Resetting tick count?

Is there a way to reset the Tick Count (ms).vi after each time it reaches a certain level?
I am running a timer function where I have one tick count inside the while loop and another outside the while loop. These values are subtracted from each other to give a ms value of the time that has gone by since the start of the program. I want an event to occur every 40 seconds, so I have the while loop stop when the timer is greater than 40 seconds. Then I would like the event to occur and the while loop to start running again until the counter reaches another 40 seconds.
The problem with this is that it seems like the counter does not reset after the first while loop is over. So the first event will occur, it will go back into
the while loop and see that the difference in tick count values is still over 40 seconds, so it will run the second event. This process repeats until all the events are done. Ideally, I would want the tick counters to be reset and the first pattern to run again where the while loop runs until 40 seconds have expired.

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Why is the Tick Count function slow when used with a .dll but fine with normal lab view code?

when using the Tick Count millisecond timer with a .dll I've written in C, I'm getting some odd timing issues.
When I code the function I want (I'll explain it below in case it helps) in LV and run it as a subVI, feeding it the Tick count as an argument, the function runs quickly, but not quite as quickly as I would like. When I feed this same subVI just an integer constant rather than the Tick Count, it takes about the same amount of time, maybe a tiny bit more on average.
When I bring in my function from a .dll, however, I start to run into problems. When I feed my function an integer constant, it is much faster than my subVI written in LV. When I feel my .dll the Tick Count, however, it slows down tremendously. I'm including a table with the times below:
             | Clock   |   Constant   |
SubVi:   | 450ms | 465ms       |
.dll         | 4900ms| 75ms         |
This is running the function 100,000 times. The function basically shifts the contents of a 2-dimensional array one place. For this function, it probably won't be a huge deal for me, but I plan on moving some of my other code out of LV and into C to speed it up, so I'd really like to figure this out.
Thanks,
Aaron

Hi Aaron,
Thanks for posting the code -- that made things a lot clearer for me. I believe I know what's going on here, and the good news is that it's easy to correct! (You shouldn't apologize for this though, as even an experienced LabVIEW programmer could run into a similar situation.) Let me explain...
When you set your Call Library Function Node to run in the UI Thread you're telling LabVIEW that your DLL is not Thread-safe -- this means that under no circumstances should the DLL be called from more than one place at a time. Since LabVIEW itself is inherently multithreaded the way to work with a "thread-unsafe" DLL is to run it in a dedicated thread -- in this case, the UI thread. This safety comes at a price, however, as your program will have to constantly thread-swap to call the DLL and then execute block diagram code. This thread-swapping can come with a performance hit, which is what you're seeing in your application.
The reason your "MSTick fine behavior.vi" works is that it isn't swapping threads with each iteration of the for loop -- same with the "MSTick bad behavior.vi" without the Tick Count function. When you introduce the Tick Count Function in the for loop, LabVIEW now has to swap threads every single iteration -- this is where your performance issues originate. In fact, you could reproduce the same behavior with any function (not just TIck Count) or any DLL. You could even make your "MSTick fine behavior.vi" misbehave by placing a control property node in the for loop. (Property nodes are also executed in the UI thread).
So what's the solution? If your DLL is thread-safe, configure the call library function node to be "reentrant." You should see a pretty drastic reduction in the amount of time it takes your code to execute. In general, you can tell if your DLL is thread-safe when:
The code is thread safe when it does not store any global data, such as global variables, files on disk, and so on.
The code is thread safe when it does not access any hardware. In other words, the code does not contain register-level programming.
The code is thread safe when it does not make any calls to any functions, shared libraries, or drivers that are not thread safe.
The code is thread safe when it uses semaphores or mutexes to protect access to global resources.
The code is thread safe when it is called by only one non-reentrant VI.
There are also a few documents on the website that you may want to take a look at, if you want some more details on this:
Configuring the Call Library Function Node
An Overview of Accessing DLLs or Shared Libraries from LabVIEW
VI Execution Speed
I hope this helps clear-up some confusion -- best of luck with your application!
Charlie S.
Visit ni.com/gettingstarted for step-by-step help in setting up your system

How long does a tick last for the Tick Count (ms) VI in LabVIEW?

I'm trying to compare the timing performance between a VI implemented in LabVIEW and another VI implemented in LabVIEW FPGA module. If I use the Tick Count in both VIs (every one in their own module), I want to know how long does a tick last in LabVIEW standard (in the computer)?
Thanks

vitrion wrote:
I have this doubt because I read that a tick lasts 55ms in the following source:
http://books.google.com.mx/books?id=en1GKs2huTcC&pg=PA33&dq=tick+count+(ms)+labview+55+milliseconds&...
My tick count provides me better results than the hardware results, which is impossible because this is the same algorithm. If I consider the 55ms time, then the FPGA is really faster.
                          Hardware          Software with                  Software with
                              (ms)        1 ms Tick Count (ms)     55ms Tick Count (ms)
Algorithm 1          49.48                   1.5552                               84.535
Algorithm 2         0.8875                  0.032                                 1.87
Algorithm 3         0.1756                  0.0241                               1.43
Algorithm 4          0.27                     0.27                                   1.32
What's your opinion?
Thanks again
I think you are misunderstanding what the value of a "tick" is. From what I gathered from reading your link (which I couldn't get to from your post, but accidentally ran into on a search) a tick of the OS clock." Curiously, though - why 55ms? That was mentioned as the tick of a Win95/98 OS!
I guess you can say that the it returns the value of the next "tick" of the OS clock and returns that value in ms. So, the value of a tick varies from OS to OS. In Windows 95/98, for example, you can only look at the OS clock every 55ms or so, but it still returns a value that represents ms.
Bill
(Mid-Level minion.)
My support system ensures that I don't look totally incompetent.
Proud to say that I've progressed beyond knowing just enough to be dangerous. I now know enough to know that I have no clue about anything at all.

Tick Count Express VI outputs '0' on FPGA target running with Simulated I/O

When I set my target to "Execute VI on Development Computer with Simulated I/O", the Tick Count VIs all output '0 every time they execute. How can I get them to output a progressive count (in the "ticks" instance) or a proper timestamp (in the "ms" instance)?
Solved!
Go to Solution.

I used LabVIEW 2013 SP1 and I was unable to reproduce this issue on my end. The screenshot below shows my result.
As shown on the Front Panel, the output from the Tick Count Express VI was not 0 on every iteration of the loop.
To make sure we are comparing the same code, can you reproduce this issue with the Tick Count shipping example? You can find this shipping example in the Toolkits and Modules>>FPGA>>CompactRIO>>Fundamentals>>Clocks and Timing>>Tick Count section in the LabVIEW Example Finder.
Regards,
Tunde S.
Applications Engineer
National Instruments

Deleting an unwanted numeric from Tick Count

I have a while loop waiting for a burst that executes every minute. I am using a local variable to trigger my "time between bursts" vi. when the burst arrives(this sends a TRUE). When the while loop is waiting, the trigger is FALSE resulting the 1st value being 0.
At present, my "time between bursts" vi produces the following results: 0(because it runs the false page in the case structure), a random number depending on tick count(incorrect), 60sec(correct),60sec(correct)and so on per while loop. The correct values should be :1st burst = 0 and then 60s thereafter.
Is there a way to delete a known error value without interupting my other code or is my code simply wrong?
Attachments:
Time between bursts.vi ‏19 KB

I have modified your VI to produce a fixed time interval between executions of the loop. The outer (Main) loop simulates teh rest of your program. The inner loop compares the time (in Tick Counts) of the Prior burst to the current time. When the difference exceed the Delay(seconds) value, the loop stops and sets New Start to the current Tick Count, which is returned by the shift register in Main loop to Prior. The waits produce timies which are not exactly one second for demonstration purposes.
The Tick Count is a U32 and will roll over to zero after about 49 days. If your computer runs that long without rebooting, you need to add some extra logic to handle the overflow.
Lynn
Attachments:
Time between bursts.2.vi ‏47 KB

LabVIEW MilliSecs support manager function and Tick Count block diagram object

Is the output of the support manager function MilliSecs (used in a CIN) directly comparable with the time returned by the Tick Count (ms) block diagram object? i.e. if they have the same value then it is the 'same' time allowing for OS specific time resolution

> Is the output of the support manager function MilliSecs (used in a
> CIN) directly comparable with the time returned by the Tick Count (ms)
> block diagram object? i.e. if they have the same value then it is the
> 'same' time allowing for OS specific time resolution
The LV diagram node is built upon the MilliSecs() function, which is
built upon various OS specific functions. It is safe to treat them as
though they are the same function and represent the same clock.
Greg McKaskle

Accuracy of tick count?

Using labVIEW 7.0 can I accept the difference between two tick counters as time in miliseconds or do I need to correct? If I need to correct is this possible, i.e. is there a stable ratio between tick number and miliseconds?

Check following thread regarding software or hardware timer
URL:http://sine.ni.com/niforum/niforum?forumDU=http://forums.ni.com/ni/board/message?board.id=170&message.id=83207&requireLogin=False
Further information can be gleamed by searching forum using tick count as start point!
chow
xseadog

Tick Count Express VI

Dear Sir,
I want to use Tick Count Express VI(µSec)
Where it is find ?
How it is find ?
Attachments:
Tick.PNG ‏130 KB

Hi bc7041,
You can find it in your functions palette under Real Time >> RT Timing >> Tick Count.
If you cannot see the Real Time Sub-Palette then you can expand the list using the double arrows at the bottom of the list. If it still does not appear then you may not have the Real Time Module installed.
For future reference, you can search for any Function or Sub-Palette by clicking the search button at the top-right of the Functions Palette.
Jamie Jones
Applications Engineer
National Instruments

Tick count precision

I am using the tick count function to acquire some data using the
serial port. The data is time critical, i don't if i can trust the tick
count function and it's precision. Does someone knows if the function
is very precise?, i do not need more than milisecond precision.
thanxs
P
Sent via Deja.com http://www.deja.com/
Before you buy.

Well.... sort of.....
the crystal itself is very good, but Windows has control over when labview
gets to see the output of the crystal ("the tick"). The problem comes
when windows decides to go off into LALA land for a while, and then either
generates an extra "fast" tick to catch up, or skips a tick so it doesn't
get ahead....
IF Windows is allowing Labview to operate at the instant that the tick
happens, and IF windows allows labview to execute the call to the serial
port in the next instant, all is well. Otherwise..... well, don't hold your
breath. In a hardware solution, the call to the port is generated on the
card, and the data is buffered (on the card) until such time as the
operating system gets around to dealing with it. The only time you have a
problem is if the operating system gets so far behind that the buffer
overflows. There's nothing wrong with using the tick count, but I wouldn't
count on it for accuracy of better than a millisecond or two. In general,
it will be right on, but when it's not, you have no way of knowing....
Craig Graham wrote in message
news:[email protected]...
>
> wrote in message
news:[email protected]...
> > Michael,
> > Do you have any ideas ?
> > Do you know what kind of timer can i use to get some real accurate time?
>
> Unless you want to change your DAQ hardware to latch the output from a
> crystal based counter on the same trigger pulse as the data is latched,
then
> read both buffers via the serial port, you're not going to get any more
> accuracy than the tick counter.
>
> The tick counter itself should be pretty accurate. The errors come in
> because of the variable time between reading the tick counter and reading
> the data from the serial port- this is far more significant than the error
> in the tick counter itself which, being crystal driven, will be pretty
good.
>
> Assuming you want a solution in software, rather than hardware, I'd take a
> tick counter reading immediately before the read operation, and one
> immediately after. You then have the two bounds between which your real
time
> value lies and you can give a value and uncertainty from there. Then it's
a
> case of living with the uncertainty- some of which is going to be present
no
> matter what you do, even if you adopt a hardware approach.
>
> It'd be useful if you could give more specific information on the
mechanics
> of how you get the data- i.e. do you issue a trigger command, then read
the
> data? If so, you just need the tick count before and after issuing the
> trigger command- assuming the trigger latches the instantaneous value
(read
> the instrument's instruction manual to find out what the relationship
> between the trigger time and the aquisition time are).
>
>

When does the tick count start

I see that the tick counter rolls over at 2^32 ms, that's 49 days. So if the counter started when Labview or the VI starts, I would never care about the rollover.
So when does it start? Can I control when it starts? I need a resolution less than 1 sec, so the second timers don't help me.
Also do other funtions or VIs continue to operate when a Wait (ms) function is running?

The tick count does not begin when you open LabVIEW or the VI. The on-line help says that the base time is undefined. There is however, no problem with you taking the tick count when you first start the VI and using that later in the VI. It's also untrue that the other time functions in LabVIEW only have 1 second resolution. They have the same millisecond resolution as tick count. If you have code in parallel with the Wait (ms) function, they will exeucte in parallel.
Also, in the future, post questions of this nature to the LabVIEW board. This board is for the NI counter/timer boards.

Why doesn't Tick count (ms) follow Dataflow ?

I have been taught basic examples of Labview data flow like multiple Add, Subtract.. blocks carry out execution at the same time and we can visually see the dataflow in Highlight execution mode.
In this example, I expect count ms to load its value the instant the first frame is run. However, in reality, count ms will only load its value to the right terminal after Search Replace string finishes (takes a long time). This means the time difference is zero !
Note that the integer constant loads the terminal the moment the frame starts, which is correct (unlike count ms)

zigbee1 wrote:
As a matter of fact, I have read papers that suggested splitting copies of code and wire them up at the same time hoping for "concurrent execution". This technique worked no doubt. But now I got to ask myself if they will really execute sequentially one block after another.
Concurrent execution is the normal case with code that doesn't have dataflow dependencies, but it's important to understand what that actually means. If you take the first article you linked to, it shows the transition from code, through the OS to two CPU cores:
This means that at most two instructions can actually execute in parallel. Because computers are really fast, this looks like they're doing many more things in parallel, but that's just because they're breaking them up into smaller chunks and going back and forth between them. This should give you the first clue as to what might be going on - what happens if there's a task which can't be broken up? You have a core which is stuck until that task is done. What happens if you have two such tasks at the same time? Now both cores are stuck and you can't do anything. That's why I said that LV doesn't guarantee parallel execution - it can't.
This problem doesn't actually happen at the CPU level, because operations there are relatively short and should actually have a fixed time, but it can happen at higher levels. Like I said, in this specific case, I'm guessing that the replace function does a DLL call to implement the regex functionality, and DLL calls block the thread they're in. This shouldn't apply to the majority of the primitives in LV, because I far as I know they directly generate machine code. The regex goes through a DLL because it's a standard implementation (PCRE) which isn't done by NI. Presumably other threads should keep running while this blocks.
So again, generally code which you write can execute in parallel (using at least some interpretation of the term. It might be true parallelism, it might be task-swapping), but there are cases where it won't happen. This doesn't change the functionality, but it can affect the actual execution. The reason it doesn't bother me is that it's not as common as you seem to now think it is. In fact, other than your post, I don't think I ran into something similar in quite some time.

Bought Premium Subscription but did not tick count...

I just bought a 1-year Premium Subscription but did not select the country for unlimited calling.......I need to now add the country to my subscription.......Can anyone help me how can I do it?
Any help would be appreciated.......
Gaurav

Hi Johnfart,
Adobe Acrobat Pro subscription does not require a serial for Activation. Please use your Adobe Id under which you have purchased the subscription to activate the product.
Please refer to this link for Activation process:- http://helpx.adobe.com/x-productkb/policy-pricing/activation-deactivation-products.html#ac tivate-how-to
Regards,
Anand

Can anyone tell me why the count tick cannot be show?

Hi All
I am trying to write a code for speed calculation, so first I am trying to familiar with the timer function. However as shown in my test code, I cannot get the result in front panel. Can anyone help me in this, please?
Attachments:
test count tick.vi ‏17 KB

Hi,
I've saved the file for 7.0.
You cannot initialise the tick count sub vi.
Reading the full help :
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.
If you want to fake an initialise, then you're simply finding the current tick count (outside the loop) and adding on 1x10E4 every time you use the tick count from then on, so a difference will actually be the difference plus 1x10E4.
Make sense?
Alternatively, use the elapsed time express vi in the execution control palette, which can take a start time.
Thanks
Sacha Emery
National Instruments (UK)
// it takes almost no time to rate an answer
Attachments:
test_timer_fixed.vi ‏73 KB

Tick count

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