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

Similar Messages

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

REGEXP_REPLACE issue/bug - replaces only every second occurence

Hi All
I am using
Oracle Database 10g Express Edition Release 10.2.0.1.0 - Product
PL/SQL Release 10.2.0.1.0 - Production
CORE     10.2.0.1.0     Production
TNS for 32-bit Windows: Version 10.2.0.1.0 - Production
NLSRTL Version 10.2.0.1.0 - Production
I need a regular expression to rename a variable in a mathematical formula, when testing my code I discovered that if the variable was repeated right after itself only one occurence was replaced. I need to only replace whole words as some variables can be a subset of a longer variable name, and variable names can have underscores in them.
Below is an example of what happens.
Can someone please tell me why this happens? Example code is:
SELECT REGEXP_REPLACE('ab+ab+ab+ab+ab+ab+ab+abc+abc+ab', '(\W|^)ab(\W|$)' , '\1xy\2',1,0,'i') from DUAL;
The regular expression matches all 'ab' with a non alpha character or beginning line before and a non alpha or end of line at the end.
I then replace the 'ab' with 'xy' and keep the original non alpha on either side. What happens is that only every second occurence is replaced.
If I place a space after every '+' then it replaces all occurences. (Obviously this is a user field in a table of mathematical formulas so I cannot expect the user to worry about this problem.)
I believe it may be due to the fact the pointer in finding all occurence is moved incorrectly and it does not find the match immediately after.
Can someone please explain this? Or am I missing something in my example.
Thanks
Dudley

Is this what you require? I changed your query a bit.
SQL> SELECT REGEXP_REPLACE ('ab+ab+ab+ab+ab+ab+ab+abc+abc+ab',
2                         '(\W|^)ab(\W|$)',
3                         '\1xy\2',
4                         1,
5                         0,
6                         'i'
7                        )
8    FROM DUAL;
REGEXP_REPLACE('AB+AB+AB+AB+AB+
xy+ab+xy+ab+xy+ab+xy+abc+abc+xy
1 row selected.
SQL>
SQL> SELECT REGEXP_REPLACE ('ab+ab+ab+ab+ab+ab+ab+abc+abc+ab',
2                         '(ab)(\W|$)',
3                         'xy\2',
4                         1,
5                         0,
6                         'i'
7                        )
8    FROM DUAL;
REGEXP_REPLACE('AB+AB+AB+AB+AB+
xy+xy+xy+xy+xy+xy+xy+abc+abc+xy
1 row selected.
SQL> -- checking data with white spaces
SQL> SELECT REGEXP_REPLACE ('ab + ab + ab + ab + ab + ab + ab + abc + abc + ab',
2                         '(ab)(\W|$)',
3                         'xy\2',
4                         1,
5                         0,
6                         'i'
7                        )
8    FROM DUAL;
REGEXP_REPLACE('AB+AB+AB+AB+AB+AB+AB+ABC+ABC+AB',
xy + xy + xy + xy + xy + xy + xy + abc + abc + xy
1 row selected.
SQL> Regards,
Jo

Why would a PXI 4071 measuring resistance countinue to increase the measured valued for each measurement?

I have a PXI-4071 DMM and I am measuring a connection in the UUT. The value should be around 0.3 ohms. The program (exe) will run aprox. 20 times and during these 20 runs the measured value will progressively increase until is is over the limit of 1.5 ohms. If I shut down the exe and run the VI as a standalone (continuous loop), the resistance will gradually come down to 0.3 ohms. I then close LabView and restart my exe and the readings are normal (0.3) but then continue to increase until they are over 1.5 ohms. This process has been repeatable for the last week. I have attached the code I am running. What could be the problem with the DMM code?
Attachments:
DMM_MeasResistance2.vi ‏64 KB

Uninitialized shift registers are a good thing to check for such a problem. Do you see the same response with a soft panel and your DMM? if not then it is in code. Uninitialized shift registers would start at 0 (default is usually 0) and will retain their values from run to run. Just a possibility dont have LV up right now so I cant check the code sorry,
Paul
Paul Falkenstein
Coleman Technologies Inc.
CLA, CPI, AIA-Vision
Labview 4.0- 2013, RT, Vision, FPGA

What's best for the battery: recharge each day or only every second day

Hi.
I can go two days on the battery of the Xperia Z1 Compact. How do I make sure the battery lasts the longest: By charging every day at about 50 percent battery, or by charging every second day at less than 10 percent battery, thus reducing the number of charge cycles the battery gets?
/Anders
Solved!
Go to Solution.

Of course,just take it back into service:
http://www.sonymobile.com/global-en/support/contact-us/
All we have to decide is what to do with the time that is given to us - J.R.R. Tolkien

How to read two files (one is updating every second, the other is constant) simoltaneously

Dear All,
I will appreciate if somebody help me.
I want to read two files, one is temperature wich is updating every second, and the other is hysteresis energy which has specific rows and is constant.
I got a program in discussion forum which read a file as it is updating. I checked this program in my case and it works.
Then I added reading hysteresis energy file to the existing file. But while i am running the program, the hysteresis energy file is read with all rows.
But the aim is that everytime which temperature updates, I need to read just one row of the hysteresis energy file.
so, in this way in every second i have a new temperature data and one row of the other file.
I tried to used "for loop" inside the program, but it did not work, becuase reading temperature will be stopped untill for loop ends.
I attached the program.
Could somebody help me how to read just one row of hysteresis energy file everytime temperature updates?
Solved!
Go to Solution.
Attachments:
Readfiles.vi ‏23 KB

I do not understand relationship between your two files.
You have another VI or app that is writing data to both files and when new temperature data added you wish just to read the new data and then read one new line of the hysteresis file?????
But is one is constant, why do you need to keep reading it?
Anyway…
The “Read From Spreadsheet File.vi” preformed an Open and a Close for each time it is called (if you will open the VI up and drill down and you will see). So that resets the file pointer back to the beginning and there for will read in the whole file from the first to the last each time if you do not set the start of read offset or number of rows.
Now the Read from Binary File does not reset the file pointer and leaves the file pointer just past the last byte read so it will start with any new bytes automaicly only giving you the new data.
I do not think you need to do the math with the Previous EOF=0 and the File size to get what I think you are trying to do.
Plus use shift reg for the Data string instead of local var
Set the mechinacl action of the stop botton to Latched
So you do not need to init the two controls
Also, I do not get the End of file encountered error (4) from the Read from Binary file if I attempt to read past. It just returns and empty string.
Omar
Attachments:
Readfiles.vi ‏22 KB

Suspends only every second time when lid closed

Hello everybody, my problem is as the subject: to suspend I have to close usually the laptop lid twice.
I'm using kde, but I have also used years ago fluxbox, tweaking scripts and using laptop-mode (which is not running now). Thanks in advance for every idea where to look.
/etc/acpi$ cat handler.sh
#!/bin/sh
# Default acpi script that takes an entry for all actions
minspeed=`cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_min_freq`
maxspeed=`cat /sys/devices/system/cpu/cpu0/cpufreq/cpuinfo_max_freq`
setspeed="/sys/devices/system/cpu/cpu0/cpufreq/scaling_setspeed"
set $*
case "$1" in
button/power)
case "$2" in
PBTN|PWRF)
logger "PowerButton pressed: $2"
poweroff
logger "ACPI action undefined: $2"
esac
button/sleep)
case "$2" in
SLPB|SBTN)
echo -n mem >/sys/power/state
logger "ACPI action undefined: $2"
esac
ac_adapter)
case "$2" in
AC|ACAD|ADP0)
case "$4" in
00000000)
echo -n $minspeed >$setspeed
#/etc/laptop-mode/laptop-mode start
00000001)
echo -n $maxspeed >$setspeed
#/etc/laptop-mode/laptop-mode stop
esac
logger "ACPI action undefined: $2"
esac
battery)
case "$2" in
BAT0)
case "$4" in
00000000)
logger 'Battery online'
00000001)
logger 'Battery offline'
esac
CPU0)
*) logger "ACPI action undefined: $2" ;;
esac
button/lid)
case "$3" in
close)
logger 'LID closed'
open)
logger 'LID opened'
logger "ACPI action undefined: $3"
esac
logger "ACPI group/action undefined: $1 / $2"
esac
# vim:set ts=4 sw=4 ft=sh et:

I actually do not understand who comands at the end - this handler.sh or the settings in Kde-powermanaging, I guess it's the second, I did remove the actions for suspend on lid close time ago. I made a test now, when I change handler.sh and check "do nothing when lid close" in kde powersettings happens exact the same: performs suspend every second time only.
button/lid)
case "$3" in
close)
logger 'LID closed'
/usr/sbin/pm-suspend
open)
logger 'LID opened'
logger "ACPI action undefined: $3"
esac
Last edited by steff (2012-07-21 17:08:46)

My test instrument is outputting a 5 line string but labview only read until the carriage return. how can I get it to read the whole string?

I have a labview sub-VI reading the string being outputted by a pH meter. The meter outputs a 5 line string and labview is only reading up to each lines carriage return, there-by giving me 5 separate strings is there anyway to rectify this and have the 5 line read as one string?
NAS1
St Petersburg FL
Labview 2010

Yes, LabVIEW will automatically update. What happens is that the old serial functions still exist in 7.1 and above but the code (the block diagram) has been modified to use VISA functions. Older versions of LabVIEW are fully supported in this manner. The only way you can avoid the automatic update is to have the old serial functions in an llb and your top level VI refer to these. Having any VI that was part of vi.lib in an llb is a very bad idea and the way to fix things is to remove any VIs in the llb that are part of the LabVIEW distribution.
I don't remember how the old serial config worked and what the new version does with the VISA Configure Serial Port. Your program should only have a single serial config and you might just be able to directly replace that with the VISA configure Serial Port.

TS1368 Why can I only download from the apps store and not itunes

Why can I only download from apps store and not iTunes.

Try logging out of your account on the iPad by tapping on your id in Settings > Store and then log back in and see if it then works.

Why does iTunes crash every time the "books" tab is opened

Has anyone had the problem of iTunes crashing every time the "books" tab is selected? Every time I open that tab and begin to browse the contents iTunes give the message that "iTunes has stopped working" "A problem caused the program to stop working correctly. Windows will close the program an notify you if a solution is available." This has been happening ever since I upgraded from iTunes 9 to iTunes 10.

maybe:
iTunes for Windows Vista or Windows 7: Troubleshooting unexpected quits, freezes, or launch issues
or
iTunes for Windows XP: Troubleshooting unexpected quits, freezes, or launch issues
and
iOS: Troubleshooting backup issues in iTunes
Doing this:
Removing and Reinstalling iTunes, QuickTime, and other software components for Windows XP
or
Removing and reinstalling iTunes, QuickTime, and other software components for Windows Vista or Windows 7
will notchange/delete/modify your iTunes media ibrary

Why does LabVIEW 2009 revert to the old icon editor?

Hi,
I have noticed that sometimes when I am trying to edit the icon in LabVIEW 2009, I get the old style icon editor from LabVIEW 8.5 days instead of the more advanced new one with layers, gliphys, etc. Once the old style editor shows up, there doesn't seem to be a way to go back to the advanced editor. Has anyone seen this behaviour? I have version 8.5 of LabVIEW still installed, should I remove it? Do I need to restart my computer?
Thanks.
Bob

Here are some of the errors I see ...
Attachments:
ScreenShot057.png ‏18 KB
ScreenShot058.png ‏112 KB
ScreenShot059.png ‏125 KB

Trying to write an if statement around the return value of a CANCEL_OPTION

I am writing a program that takes an input String using JOptionPane. The String can be made of only letters of the A-Z alphabet and the space character. I have written an error-checking loop that will pop another input box up along with an error message if any invalid character is detected. The input box has an 'ok' button and a 'cancel' button. As it is, if you hit cancel, the program crashes and you get a NullPointerException. All I want to do is place an if statement inside of the error-checking loop, immediatly after the code to pop up the second input box, that simply does System.exit() and exits the program correctly(rather than crashing) if 'cancel' is clicked.
My attempt at such an if statement is visible in the following code(letter is a boolean variable defined earlier, and message is the input String that has already been read in):
               letter = isValidMessage(message);
          while(!letter)
               message = JOptionPane.showInputDialog(null, "Message must contain only A-Z, a-z, or space character...");
                        if(JOptionPane.CANCEL_OPTION > 0 //or ==0 or ==1 or ==2, nothing works//)
                            JOptionPane.showMessageDialog(null, "No valid message entered - program will terminate...");
                            System.exit(JOptionPane.CANCEL_OPTION);
               letter = isValidMessage(message);
                }The if statement doesn't work correctly. If you click 'cancel' when the input box comes up, the program does terminate as it is supposed to. The problem is that if I type something in the box and click 'ok', it also causes the program to terminate rather than continuing. I've tried changing the > to ==. I've tried changing 0 to 1 to 2 to -1(I really am not sure which int return value of CANCEL_OPTION corresponds to which event). I think once I got to do the exact opposite...that is to say, it would continue on with the program whether I clicked 'cancel' or 'ok'. Which is equally bad. I don't know what I'm doing wrong.
It's probably something simple that I'm just overlooking.

Well, here's what CANCEL_OPTION is, according to the JOptionPane class:
/** Return value from class method if CANCEL is chosen. */
    public static final int         CANCEL_OPTION = 2;However, I believe you're going about this in the wrong way.
With JOptionPane, whenever you show a dialog, it usually returns whatever OPTION the user chose.
For instance,
    int choice = JOptionPane.showConfirmDialog(parentComponent, "hello");That will bring up a dialog centered on parentComponent, with a message of "hello".
It will have the default options (YES_NO_OPTION).
What it returns is the option the user chose.
There are 4 possible things it can return:
YES_OPTION, when user clicks "Yes"
NO_OPTION, when user clicks "No"
ERROR_OPTION, when an unforseen error occurs and the dialog closes
CANCEL_OPTION, when the user clicks "Cancel" (if that OPTION type were being used), or if they close the dialog
So this is how you would check for CANCEL_OPTION:
    int choice = JOptionPane.showConfirmDialog(parentComponent, "hello");
    if (choice == JOptionPane.CANCEL_OPTION) {
        // User cancelled
    else if (choice == JOptionPane.YES_OPTION) {
        // User chose yes
    // EtcSo you see, going about it like this:
if(JOptionPane.CANCEL_OPTION > 0 //or ==0 or ==1 or ==2, nothing works//)Is really the wrong way, because you're not checking what the user DID, but just what the constant variable "CANCEL_OPTION" is.
However, it seems as if you're in a unique situation where you don't want the OPTION chosen by the user, but an input String.
This is all well and good, but I think this limits how you can interact with the user, as the "showInputDialog" methods return the String the user input- not the OPTION they chose, and you need to use both.
What I've done in the past is created a simple JPanel with its own JTextField.
I pass the JPanel in as the "message" parameter of a showConfirmDialog call, and get both the user input and their chosen OPTION based off a getText call to the JTextField and the OPTION constant returned by showConfirmDialog.
Basically,
JPanel promptPanel = new JPanel(new BorderLayout());
JTextField promptField = new JTextField();
promptPanel.add(promptField, BorderLayout.CENTER);
int choice = JOptionPane.showConfirmDialog(parentComponent, promptPanel, "Input", JOptionPane.OK_CANCEL_OPTION, JOptionPane.QUESTION_MESSAGE);
if (choice == JOptionPane.OK_OPTION) {
   // User chose OK, see if invalid characters were entered
   String input = promptField.getText();
else if (choice == JOptionPane.CANCEL_OPTION) {
   // User cancelled
}Hope that helps.
(note that I'm unsure if showConfirmDialog can accept OK_CANCEL_OPTION as its OPTION parameter, as it says only YES_NO_OPTION and YES_NO_CANCEL_OPTION can be used, but I seem to remember using it in the past. if OK_CANCEL_OPTION doesn't want to work, then use one of the other two and adjust your if statements accordingly)
Cheers!
Edited by: LukeFoss on Oct 9, 2007 10:39 PM

Labview as the active window disables 1 or 2 concurrent while loops

I am trying to get familiar with new mutltifunction DAQ hardware from IOtech - a DAQborad/2000.
I have a simple vi consisting of two while loops which should be running in parallel. One acquires analog input data, the other handles DAC outputs.
When I run the vi, the analog acquisition while loop runs fine, but the DAC while loop will not run if labview is the active window on the pc (frontpanel or diagram). If I make another window active, both loops will update as they should.
I can resize a windows explorer window to make it small, run my vi, make windows explorer the active window and see the vi running both loops and updating as it should in the background. If I use the "Highlight Executi
on" tool on the diagram screen, both loops run as they should.
Any ideas?
Thanks,
Mike

> I am trying to get familiar with new mutltifunction DAQ hardware from
> IOtech - a DAQborad/2000.
>
Many third party drivers default to running in LV's UI thread, and if
they put the thread to sleep, other LV threads can run, but not the UI.
It is also possible that one of the loops is hogging while the other
is being starved.
So, I've got two suggestions to try. First try putting a delay of a few
ms in the busy loop. This might help with the starvation. The second
thing to try is to open up the IOTech VI and try setting the DLL node to
be reentrant. This will allow the node to run in any thread and not
force it into the UI thread. Beware that if the DLL isn't threadsafe,
this could lead to data corruption or crashes, and before leaving it s
et
this way, you should probably contact IOTech to see if their DLL is
threadsafe. If it is not, contact NI tech support and they can help you
determine if it is safe in this case to leave it running in other threads.
Greg McKaskle

How can I reset the value of an indicator in a while loop, from another synchronous while loop?

I am running 2 synchronous while loops, one which is keep track of time, and the other is measuring periods. In the while loop that is measuring periods, I have a boolean indicator displaying whether the signal is on or off. My problem is that when the signal is off, the VI I use to measure the periods is waiting for the next signal, and displays the boolean value from the previous period measurement. While this VI is waiting, I want the indicator to display false and not the value from the last iteration of the loop.
I am using LV 5.1 for MAC.

Two things you can try:
In preface to the first, the most common (perhaps ONLY) use of local variables should be in transferring data between parallel loops. This is a matter of discipline, and creates programs that are easier to understand, take less time and memory, and are just plain cleaner. Having said that, to transfer data between loops, use a local variable.
Second solution: Instead of setting the value to false, just hide the indicator in question by using control references (property nodes for prev. version of LabVIEW). Control references are a great way to control items on a dialog or HMI screen.

The agentTZRegion value in emd.properties is not in agreement with what age

Hi all,
A grid agent 10.2.0.5 on Red Hat EL has been down several days
When I try to start it, it shows the following error:
The agentTZRegion value in /gridagent/OracleHomes/agent10g/sysman/config/emd.properties is not in agreement with what agent thinks it should be.Please verify your environment to make sure that TZ setting has not changed since the last start of the agent.
If you modified the timezone setting in the environment, please stop the agent and exectute 'emctl resetTZ agent' and also execute the script mgmt_target.set_agent_tzrgn(<agent_name>, <new_tz_rgn>) to get the value propagated to repository.
Consult the log files in: /gridagent/OracleHomes/agent10g/sysman/log
TimeZone was not changed in server.
In emagent.nohup I can see:
Mon Oct 4 12:01:38 2010::The agentTZRegion value in /gridagent/OracleHomes/agent10g/sysman/config/emd.properties is not in agreement with what agent thinks it should be.Please verify your environment to make sure that TZ setting has not changed since the last start of the agent.
If you modified the timezone setting in the environment, please stop the agent and exectute 'emctl resetTZ agent' and also execute the script mgmt_target.set_agent_tzrgn(<agent_name>, <new_tz_rgn>) to get the value propagated to repository -----
--- Standalone agent
----- Mon Oct 4 12:09:26 2010::tzOffset for America/Buenos_Aires is 0(min), but agent is runnning with tzOffset -180(min)
----- Mon Oct 4 12:09:26 2010::trying again after waiting for 1 sec to account for daylight transition
----- Mon Oct 4 12:09:26 2010::tzOffset for America/Buenos_Aires is 0(min), but agent is runnning with tzOffset -180(min)
----- Mon Oct 4 12:09:26 2010::Mismatch detected between timezone in env (America/Buenos_Aires) and in /gridagent/OracleHomes/agent10g/sysman/config/emd.properties (America/Buenos_Aires). Forcing value to latter.. -----
Any suggestion ?
BTW, timezone no both emd.properties and repository is America/Buenos_Aires
Thanks a lot
Edited by: user13340418 on 04-oct-2010 8:31
Edited by: user13340418 on 04-oct-2010 8:33

hi,
Please see MOs note 403018.1. Your Os time zone might have some differences with your agent time zone.
Salman

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

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