Restarting counter in Timed Loop

I have a timed loop inside a state machine, used to start/stop a data acquisition sequence.
It works fine, but I'm monitoring the "i" count and Actual End [i-1] values and after the start/stop/start sequence
these values continue to grow and don't get reset to zero. I would expect a While Loop to reset the "i"
variable every time is is called, but I don't see any option for resetting the time looped.
I can get around it, but I would expect a reset method for this loop, so I'm just wondering if I'm missing something.
Maybe I need to use "Create Timing Source" instead of the setting it iin the dialog box?
Labview 2010f1 on Windows Vista SP2 PC

This might help. Here is a part of the png file you posted. I put in "Structure Name>" to point to the Structure Name input. Notice that the name "bob" is listed as the Structure Name. You must be on Win7 which uses different fonts than XP - that's probably why the name is only half visible.
Note that the Clock name is connected to the (timing) Source Name input.
I'm attaching an updated version of the file with the Timing Loop name wired directly.
Thanks for posting your timed loop interations3 program in 2009. When I run this code, the Iteration Count DOES reset when the Timed Loop is restarted.
steve
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question. Give "Kudos" to replies that help.
Attachments:
New timed loop interations.vi ‏42 KB

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I am getting occasional timing errors in a timed loop under windows XP and would like to count the number of errors, but I can't find a simple software counter vi

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The attached shows a very simple demo (LabVIEW 7.1).
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Using timer/counter with PCI-6221/USB-6210 to control timed-loop VI

Dear all,
I need to ask about two devices and one of their functionalities, PCI-6221 and USB-6210. For our NI-based system, we need to control some timings in a Timed-Loop vi, for that currently we are using PCI-6221 and we give external TTL signal (at 1 kHz) to it,
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Ben,
I having read previous email which I send earlier with general overview, we discussed in more detail within our team and I am giviing the specific answers.
Please check in RED the most recent answers. Blue are the questions/suggestions by your side.
1.    Using Internal hardware clock of PCI-6221 would enable us get rid of external clock, but how to divert the internal hardware clock to the current settings. Any idea (can you provide us with some reference manul for otherwise). I mean is there some flag-bit etc. or VI
2.       Is it also meant that with the installation of RTOS the timed-loop can directly get the timing source from the internal hardware clock PCI-6221? --- How???
3.       In order to make desktop to work as RT system, what is the hardware (motherboard, processor, etc..) requirement? What are the LabVIEW modules (specific name) that needed to be installed? Our platform is LabVIEW 8.6. (Currently we have windows-7 with i7 core processor)
What kind of application are you intending for this system? ---- high-speed laser scanning system.
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How to pause and restart a timed loop in Labview

I am trying to pause and then restart a timed process (series of stepd that happen at precise times), which is implemented using a timed loop.
I was wondering if anybody out there can give me a hint.
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Roxanne,
Well, it's not exactly a "pause", but here's a way to stop and re-start your Timed Loop.
See the attached example in LV2010.
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Releasing the Queue stops the While Loop when you end the program.
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steve
Help the forum when you get help. Click the "Solution?" icon on the reply that answers your
question. Give "Kudos" to replies that help.
Attachments:
timed loop.vi ‏39 KB

Why do we lose counts through a timed loop?

I have written a program to count the rising edges of a square wave produced by a function generator using the DAQmx functions. The counter is read in a time loop with a period of 1 second, so we take a sample once every second. It appears that the program is working correctly accept for the fact the the counts are continuously 2% lower than they should be. We are guessing that this is due to the fact that the timed loop really isn't taking a full second to complete each iteration. Any suggestions on how to fix these timing errors? The counters are read from the NI 6608 Device if that is of any help.

Please post images of your code so that we can be off assistance.
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Strange DAQmx Timing Source Timed Loop Error

I have a digital edge counter fed into a timed loop. Everything works fine until I stop the loop, and stop the DAQ task. Once I restart the loop it fails with "resource is reserved". Attached is my code.
Thanks
Solved!
Go to Solution.
Attachments:
daqloop.JPG ‏136 KB

Here is a piece of code to illustrate the issue. If the timing source is created in the loop (it will be created each loop iteration) the error occurs. If it is moved outside the loop, and only created once the issue is resolved. Is there a way to RELEASE the timing source so that it can be created again? If the VI is stopped, this "resource" is released. I want to programatically release it.
Note the error comes from the timed loop Error terminal that is Probed (50).
Message Edited by bkb on 10-08-2008 09:52 AM
Message Edited by bkb on 10-08-2008 09:53 AM
Attachments:
ts.jpg ‏57 KB

Timed loop and CPU usage

Platform is WIN_XP Pro and machine is a P4 at 2.5Ghz with 512 Mb ram.
LV7.1 + PCI 6229
I am using 50ms Timed loop for running a state machine inside it
and also a whole lot of other things like reading / writing
DAQMx functions; file I/O functions and such. As the
project involves a main and sub-panlel set up local variables
could not be elimnated fully and there should be something like 150 of
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given time depending on the SM staus.
Problem :
Once started the "Finished late" indication is off and
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I am at a loss to understand what is happening ? WIll
breaking down the single Timed Loop to multiple ones help ? WIll
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Raghunathan
Raghunathan
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Hello,
It sounds like an interesting problem. It would be worth some experimentation to figure out what's going wrong - attempting to decouple major "pieces" of the code would be helpful. For example, you could try breaking your code into multiple loops if that makes sense in your architecture, but perhaps you could even eliminate all but one of the loops to begin with, and see if you can correlate the problem to the code in just one of your loops.
Another concern is that you mention using many local variables. Variable read operations cause new buffer allocations, so if you're passing arrays around that way, you could be hitting a problem of forcing your machine to perform many allocations and deallocations of memory. As arrays grow, this can be a bigger and bigger problem. You can use other techniques for passing data around your block diagram, such as dataflow if possible (just simple wires), or queues where dataflow can't dicatate program flow completely.
Hopefully looking into your code with the above considerations will lead you in the right direction. In your case, removing code so that you can identify which elements are causing the problem should help significantly.
Best Regards,
JLS
Best,
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LabVIEW RT, Timed loop, finished late, Call by reference

I have a timed loop triggered by the sample clock of a DAQ-Card. The sample Clock is 8 kHz and the loop will run with dt = 4. Normally the loop is running without finished late[i-1]. But from time to time it happens that the loop is running extremly longer which means instead of 0.5 millisec it needs 4 - 5 millisec. It seems this doesn't never occur while accessing DAQmx.
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Using 7.1.1, 8.5.1, 8.6.1, 2009 on XP and RT
Don't forget to give Kudos to good answers and/or questions

To keep you informed:
I stripped the application and have left only the measurement storing module and the timed loop. The loop was using the microsecond timer running each 500 µsec. Additional all Non-Real-Time modules were loaded and only one module creates a XML string and sends it to the communication layer which will drop it because no TCP/IP port is open. The creation of the XML string is done each 300 ms.
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Using 7.1.1, 8.5.1, 8.6.1, 2009 on XP and RT
Don't forget to give Kudos to good answers and/or questions

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Bit of an odd one that had me scratching my head.
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W.r.t. system resources, there's very little else running on that system, but that doesn't normally stop Windows
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Timed loop

Hi all ! I have a question ...
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Is there a way to immediately abort a timed loop

Im writing a program that when completed, could run for a very very long time. But I need a timed loop to execute every 60 secs. The two option I have come up with are these
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First way means I can't stop the loop until the time expires (more desirable than the 2nd option), the second option relies on the ability to determine when a minute is up based upon a 1Hz iteration rate, but from what I am reading, the iteration counter will eventually get to its max value and just hold its value, while the loop continues to execute (hence I lose my logic for content execution)
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Solved!
Go to Solution.

If you want to use a timed loop, you can stop it at any time using the Stop Timed Structure tool. (even if the conditional terminal is hardwired to never stop!)
For example in the following code draft, pressing the stop button will stop and complete the timed loop immediately, no matter how long the interval is.
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LabVIEW Champion . Do more with less code and in less time .
Attachments:
StopTimedStructure.png ‏12 KB

Timed loop in a subvi, one or the other runs but not both.

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Test Of Timed Loop.zip ‏72 KB

Never Mind!
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I'm using a cRIO for motion control. I have a counter that I modified a little bit (from the softmotion examples) and once compiled (unfortunately after 1 hour ...), I have an error saying that I couldn't acheive the desired timed loop clock of 40.4 MHz... the clock rate able to acheived was 40.16 MHz (really near)...
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I know that a 9411 device can run in a SCTL at 40Mhz.
What I don't understand is that I can't run the loop below than 40Mhz.
I read in the FAQ that some device can not run above 40Mhz, but in my case, I want to run in slower....
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It is really unclear what your question is. Could you clarify?
If you are struggling with why you have a broken wire it is because you are sending an array to the stop of the loop. When you use the array size function on a 2D array it returns a 1D array with the size of each dimension. When you then use the greater than function it returns a 1D array of Booleans. It compares each element of the array size to the current count of the iteration terminal.
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DAQmx Config for Timed Loop.vi ‏94 KB

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