Power factor in signal express

I have my voltage and current waveforms into SE and am having trouble trying to measure the phase angle between them so that I may calculate PF for logging purposes. Is this possible with SE or do I need a higher powered platform (LabView)?
Thanks
Randy

Hello all,
I would like to clarify that LabVIEW VIs can be used in signal express, however they need to follow specific guidelines defined in the following knowledgebase articles:
VI Guidelines for User Defined Steps In SignalExpress
Using a LabVIEW VI with LabVIEW SignalExpress
The EPM VI's , linked in previous post, could be modified to conform to these guidelines, however to do so LabVIEW is required.
To use LabVIEW VI's in Signal express follow these steps:
1. Add Step --> RUN LabVIEW VI (choose proper version for VI).
2. Select VI or source distribution (.llb) Path and configure the proper settings for your application.
More detailed information on how to run a Labview VI in Signal Express can be found at the following link: Signal Express Help: Run a LabVIEW 8.6 VI
Regards,
CharlesD
Digital MultimetersSchedule a Free 1 Hour LabVIEW Tutorial with an NI Applications Engineer

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Signal express LE on host machine

Hi,
I'm having a problem with an application I built.
I want to control my tektronix power supply with Signalexpress LE on a host machine.
LabVIEW is not installed on this machine but I have installed LabVIEW run-time.
All others application I built work fine on my host machine.
I barely can't control my power supply on this host machine...
My application is fine because it's working on my development machine.
Is there any software to install on a host machione to make my application work?
Thank you!
Nicocmd

Hi nicocmd,
Just to make sure I understand the case. You built a project that communicates with a Tektronix power supply in Signal Express. Now you want to deploy that project to another computer that only has the run-time engine installed? What do you mean by barely can control?
Best Regards,
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How can i generate AMI line codes in LabView signal express?

i wish to conduct a project that uses AMI line codes. but i have a hard time using signal express to generate it. can anyone help me with that?

Hello Barry,
That is really a problem, in LabVIEW, we can only convert vi to the previous version, I have version 7.1 and so I can only convert to version 7.0 and you cannot open this too.
But I think that it's very easy to do what I'm trying to explain you.
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So to calculate the real value of the peaks, you have to multiply them by df and add them f0.
Sorry by the big text and sorry if I went too much in detail,
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Signal express project documentation

I've been having problems with the "project documentation" section of my Sound And Vibration Assistant (based on signal express). It's been locking up and corrupting previously good projects. When I add the peak search step to the documentation and hit "view as - cascade" everything seems to fail, the project locks up, is not responding, it doesn't even let it close, have to call task manager to close it, after that when I try to open again that same project, it doesn't even open fully and is locked up again. Any help with this would be apreciated.

Hello Seth, I'm attaching a couple of files. The first one contains a screen shot of the steps that I'm using in the project, The second one is the message that I received when SAV assistant quit on me and the third one is the printout of project documentation before it started failing, the second to last graph is the one I think is creating most of the problems, when I removed that graph from project doc it worked fine, other than when I tried to resize one of the other graphs.
I'm gathering data from an accelerometer I take the time domain signal and transfer it to freq domain, zoom in on the power spectrum linear magnitude scale.
Let me know if you need any other info.
F@SII
Attachments:
SAVsteps.docx ‏200 KB
SCREEN SHOT FAILURE LABView.docx ‏213 KB
hppscan6.pdf ‏233 KB

Why can't I use Signal Express as a Front End to my LV application?

Why not make an API for Signal Express so I can use its
functionality as a front-end to my LV
applications.
It is very powerful and user friendly so why have LV developers recreate
the wheel? Give an interface to access a SE project via LV
to get data and pass results into LV
so we can then use its power to make quicker more user friendly applications.
SE could run in the background as the analyzer and the LV application call SE to get the portions of
the data it needs.
Even an automatic VI compiler on SAVE would be a start so a user
could edit a project in SE close it and it would compile the VI which the LV program calls.
LabVIEW developers typically do not have 6-18months to
design and perfect a powerful user friendly interface and are stuck using MAX
and its inadequacies which is much less impressive.

Arron,
I agree that it would be a good idea to include this functionality and have filed a product suggestion. To file a suggestion, you can go to www.ni.com/contact and click on the link in the lower left hand corner for product feedback. Thanks for letting us know!
Regards,
Craig D
Applications Engineer
National Instruments

Calculate Impedance, Power Factor & Type Of Power In RLC Circuit

Good Evening
No suprises to what im looking to investigate today.
I have a initial circuit which contains a AC supply, Resistor and Inductor only, I must calculate the impedance, supply current, power factor & angle, and type of power that is consumed in the circuit.
I must then create a modified circuit in which i must improve the power factor to 0.95 and specify the value of capacitance required!
I must then calculate the impedance, supply current, power factor & angle and the type of power consumed in the circuit.
I have never really used multisim before, just want to make sure my calculations are correct as the values I have been given to work with are producing tedious amounts of impedance. My XL=24kOhm
I have tried to use the impedometer but not quiet sure how to wire it correctly. Same goes for the watt meter not sure how to wire the terminals for V and I.
Appreciate any help and advice I have provided some images of my initial circuit I have not specified the value of C as im not sure what it must be to give me a PF of 0.95.
Regards
Ps pardon the amatuer mistake forgot to add a ground (fool)
Carl
Attachments:
INITIAL.png ‏44 KB
MOD.png ‏44 KB

Hi Hass,
Here is an article on Calculating the Impedance in Multisim.
http://digital.ni.com/public.nsf/allkb/9F8D30235DE3EC0186257592006B23A2
Similarly, you can add Expression to Calculate the Power Factor or other circuit parameters.
Hope this helps!
Regards,
Chen_T
National Instruments

Why the acquisition with DAQmx is different by using Labview 8.2 from Labview signal express?

Hello,
I am using a PCi-6281 to acquire a voltage. When I am using Labview signal express with only the step to acquire I read the good signal with the exact voltage. But when I am using my VI, the y axis and the values recorded are wrong. Why this difference appears?
I insert a picture with both signal: at the top is the signal from my vi (wrong measurement) and at the bottom is the signal from labview signal express (correct).
The vi I am using is the example Cont Acqu&Graph Voltage-To file (binary).vi.
Thank you for your answer!
Sophie
Sophie

I am using the binary file because it requires the minimum change in another VI. I have tried to change in scaled data but now my second VI has not enough memory to display all data.... What's wrong? Here is my second VI. Totest with data you need to insert a number in the "scaling factor" if not the dat are multiplied by zero...
thanks for your help!
Message Edité par stage84 le 07-24-2009 10:11 AM
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Signal Express Large TDMS File Recording Error

Hello,
I have the following application and I am looking for some tips on the best way to approach the problem with Signal Express:
I am attempting to using Signal Express 2009 (Sound and Vibration Assistant) to collect random vibration data on three channels over an extended period of time -- about 20 hours total. My sample rate is 2kHz. Sampling at that rate over that period of time invovles the creation of a very large TDMS file, which is intended for various types of analysis in signal express later or some other application later on. One of the analysis functions to be done is a PSD (Power Spectral Density) plot to determine the vibration levels distributed over a band of frequencies during the log.
My original solution was to collect a single large TDMS file. I did this with Signal Express recording options configured to save and restart "in current log" after 1 hour worth of data is collected. I configured it this way because if there is a crash/sudden loss of power during data collection, I wanted to ensure that only up to an hours worth of data would be lost. I tested this option and the integrity of the file after a crash by killing the SignalExpress process in the middle of recording the large TDMS file (after a few save log file conditions had been met). Unfortunately, when I restart signal express and try to load the log file data in playback mode an error indicating "TDMS Data Corrupt" (or similiar) is displayed. My TDMS file is large, so it obviously contains some data; however, Signal Express does not index its time and I can not view the data within the file. The .tdms_index file is also present but the meta data.txt file is not generated. Is there any way to insure that I will have at least partially valid data that can be processed from a single TDMS file in the event of a crash during mid-logging? I don't have too much experience dealing with random vibration data, so are there any tips for generating vibration level PSD curves for large files over such a long time length?
My solution to this problem thusfar has been to log the data to seperate .TDMS files, about an hour in length each. This should result in about 20 files in my final application. Since I want to take a PSD, which ends up being a statistical average over the whole time period. I plan on generating a curve for each of these files and averaging all 20 of them together to get the overall vibration PSD curve for the 20 hour time period.

JMat,
Based on the description of your application, I would recommend writing the data to a "new log" every hour (or more often). Based on some of my testing, if you use "current log" and S&V Assistant crashes, the entire TDMS file will be corrupted. This seems consistent with what you're seeing.
It would be good if you could clarify why you're hoping to use "current log" instead of "new log". I'll assume an answer so I can provide a few more details in this response. I assume it's because you want to be able to perform the PSD over the entire logged file (all 20 hours). And the easiest way to do that is if all 20 hours are recorded in a continuous file. If this is the case, then we can still help you accomplish the desired outcome, but also ensure that you don't lose data if the system crashes at some point during the monitoring.
If you use "new log" for your logging configuration, you'll end up having 20 TDMS files when the run is complete. If the system crashes, any files that are already done writing will not be corrupted (I tested this). All you need to do is concatenate the files to make a single one. If this would work for you, we can talk about various solutions we can provide to accomplish this task. Let me know.
Now there is one thing I want to bring to your attention about logging multiple files from SignalExpress, whether you use "current log' or "new log". The Windows OS is not deterministic. Meaning that it cannot guarantee how long it takes for an operation to complete. For your particular application, this basically means that between log files there will be some short gap in time that the data is not being saved to disk. Based on my testing, it looks like this time could be between 1-3 seconds. This time depends heavily on how many other applications Windows has running at the same time.
So when you concatenate the signals, you can choose to concatenate them "absolutely", meaning there will be a 1-3 second gap between the different waveforms recorded. Or you can concatenate them to assume there is no time gap between logs, resulting in a pseudo-continuous waveform (it looks continuous to you and the analysis routine).
If neither of these options are suitable, let me know.
Thanks, Jared

How to measure power factor in FPGA

Hello,
I am acquiring analog signals of 50 Hz frequency using NI 9215 and cRIO 9073.
I am using DC and RMS measurement FPGA VI to get the RMS value of voltage and current in the FPGA.
Similarly, i need to measure the power factor taking the voltage and current values in the FPGA.
I am able to get the power factor in RT using the VI , which calculates phase angle.
But in FPGA, I guess it is not direct. Please can I know, how to obtain the power factor in FPGA itself.
Thank you.
Hema

OK, I haven't used FPGA version, so I'm out of my cage. If it is indeed limited, as JamesBeams says above, then there's not much you can do except rework the math yourself.
I would think that such a VI would not be allowed to be transferred onto the FPGA in the first place, but that's just a guess.
Perhaps there's a list of acceptable / unacceptable FPGA vi functions, and you could confirm that it's not available.
You might also ask the tech support folks:
http://sine.ni.com/apps/utf8/niae_asc.main
Message Edited by CoastalMaineBird on 06-29-2009 05:14 AM
Steve Bird
Culverson Software - Elegant software that is a pleasure to use.
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PWS4000 and Signal Express

Hi,
I recently get a PWS4305 power supply, I installed SignalExpress as recommended.
I just want to generate a signal and control the PWS with labview.
So I selected 'add step' ->'tektronix'->'generate a signal' -> 'tektronik power supply'.
Here, a display shows two line, one for the voltage, another one for the current.
I can find my PWS in the VISA Ressource. But how can I generate a signal ?
Thank you

egfrgr,
I believe you may need to download and install the following SignalExpress step before using your PWS4305:
LabVIEW SignalExpress Step for PWS4000 V2.0.0
Please read through the release notes for installation and usage instructions, copied here for reference.
Steps for using the Steps:
1. Run the setup.exe provided as part of Step Installer.
2. Open the LabVIEW SignalExpress Tektronix Edition software.
3. Click "Add Step" in the LabVIEW SignalExpress Tektronix Edition main menu and select Tektronix-> Generate Signals -> select your instrument series.
4. The Step appears in the Project View of Signal Express and is ready to be used.
5. Connect the instrument to your PC.
Note: You can check the connection to your Instrument using the Measurement & Automation Explorer or the TekVISA OpenChoice Instrument Manager.
6. Next, select the device in the LabVIEW SignalExpress step by selecting the "VISA Resource" tab and selecting the device in the "VISA Resource Name" drop down list. At this point, the interface is ready for use.
Jared A.
Applications Engineer
National Instruments

Power factor Measurement using myDAQ

I have potential transformer (PT) & current transformer (CT) and want to measure the phase angle between then later i can do COS angle to get the power factor of the input signal.
I want to implemet this only by using myDAQ please dont suggest me to use another DAQ

You can build your own counter from the Digital input as shown below. For measuring the time period please follow this thread.
The best solution is the one you find it by yourself
Attachments:
CounterDI.vi ‏7 KB

What are the main differences between Signal Express and Labview?

National Instruments provides a matrix so one can quickly compare the
various versions of Labview but no comparison of Signal Express with
Labview. Hence how does Signal Express compare with Labview? What
are some of the things one can do with Labview one can't do with
Signal Express?
Howard

hrh1818 wrote: Which version of Labview are you referring to? I don't consider the graphical version of Labview to be a full featured programming language. LabWindows/CVI is by a long shot a lot closer to being a full featured programming language than the graphical version of Labview.
Howard,
You clearly don't know what you are talking about. There is no "graphical version" of LabVIEW, there is just LabVIEW. Click on the article "Is LabVIEW a general purpose programming language?" written by the Jeff K. for some easy reading from a few years ago. It is all still true (except that object oriented features and recursion have been added in recent versions).
One of the main points at this years NI-week was the discussion of how processor development is switching more and more to multicore designs to improve performance because a simple boost in clock frequency is becoming more difficult. Linear, text based code is not well suited to take advantage of multticore design, while the dataflow based LabVIEW programming language automatically scales well to multiple processor cores, without any need to rewrite older code. I would say that only LabVIEW is futureproof in this respect. LabVIEW programmers are not wimps that are simply too stupid to write text based code. LabVIEW is not a toy language for people that don't want to learn a "real" programming language.
LabVIEW is arguably the best programming language in terms of getting things done! I've never felt limited with LabVIEW and my programs often don't even have anything to do with data acquisition or instrument control. The difference between text based code vs. LabVIEW is like "DOS vs. Windows", "Radio vs. HD television". "Trilobyte vs. Homo sapiens" (sorry Putnam ). Text based code is monochrome, archaic and outdated and its linearity imposes unecessary constraints on the programmer that can only be (partially) overcome by wasting even more time throwing even more code at it.
Sure, a seasoned text based programmer will initially have problems adapting to LabVIEW, just because you would need to adapt to and embrace the power of dataflow and not try to make a literal translation of the text code to LabVIEW, retaining old habits. If you get stuck, come back and ask here in the forum.
You were looking for object oriented features and failed. All you need to do is a quick site search. All the information is out there. Just because you cannot find it in the first five sentences of the glossy brochure does not mean it does not exist. Maybe you want to read one of the application notes such as:
LabVIEW Object-Oriented Programming: The Decisions Behind the Design
In general, you should avoid judgement until you have all information. Your opinions seem quite biased and superficial and not really based on hard facts.
Initially you asked about the difference between signal express and LabVIEW.
hrh1818 wrote:
> What kind of measurments do you want to do and what kind of requirements do you have?
> You can also see for yourself and download evaluation version of both.
No thanks, there has to be a better way to get an answer to my
question than get involved in a two month study project.
If you would answer the first question quoted above, we could certainly help you with the decision. Isn't that the main purpose of this thread?
You can also contact your local LabVIEW Field Engineer to go over your requirements and help you make a decision. They usually know their stuff!
Message Edited by altenbach on 09-02-2007 11:51 PM
LabVIEW Champion . Do more with less code and in less time .

Report generation toolkit and signal express user step : problem of closing reference in "Stop" event

Hi all,
I'm trying to make a package of Vis to easily make Excel reports with Signal Express. I'm working on LabVIEW 8.2.1.
I'm using the report generation toolkit, so I build a .llb from my project which contains all the hierarchy of my steps, but also the hierarchy of dynamic VIs called.
I have made some steps, like "Open Workbook", "Write Data", etc.
My steps run well, excepts one step : "Close Workbook".
If my "Close Workbook" step is firing on "Run" Signal Express event, I have no error, so my reference is properly closed.
But if my "Close Workbook" step is firing on "Stop" Signal Express event, I have an error "1", from "Generate Report Objectrepository.vi".
I feel that I'm trying to use a reference which has been killed in the "Stop" step...
I would like to know what exactly do Signal Express on "Stop" event and why my close function does'nt run well.
Thanks,
Callahan

Hi Callahan,
SignalExpress (SE for short) does the following on the Stop event:
1. Takes the list of parameters that SE found on your VI's connector pane, and sets the values that the user set from the "Run LabVIEW VI" configuration page, if any.
2. Then tells the VI that SE is running the Stop event by setting the Enum found on your VI's front panel. This in turn should produce some boolean values telling your VI to execute the Stop case.
3. The VI is then run, with those values and states.
4. SE checks to see if any errors where returned.
5. Since this is the Stop event, SE releases the reference to the VI which it possesses.
Questions for you would be, is the reference to your Workbook linked to a control on your connector pane, or held in a uninitialized Shift Register. If it's held in a Shift Register, SE would not be aware of it, and would not be able to affect that reference.
Hope that helps. Feel free to post your LLB if it doesn't.
Phil

Can I save data in a snapshot from signal express 2013 LE?

Can I save data (in txt or excel format) from a snapshot from signal express 2013 LE? My data buffer is too larege to export to excel. When I try to take a snapshot, I do not see any data. Are snapshots supported in the LE mode? This is the free version that comes with the USB 6009 ADC.

Yes, the snapshot function is available for SignalExpress 2013 LE. Does the snapshot function as intended when you try other projects?
Daniel P.

How do I get channel names written into a logged ascii file in Signal Express

Hi there,
This maybe a rookie question but I am a relative rookie to this software, and I hope it has an easy fix!
Background:
Take a load of analogue inputs from a DAQ device into Signal Express, first thing that hits me is that unlike labVIEW you cannot right click in the channel configuration window and change the name from say... Dev2_ai0 to Air Pressure? I feel that if this was possible then I would overcome my problem? anyway I can't so onwards...
I goto the DAQmx Acquire window on the top left and can right click and rename the channel, which is great... however this does not translate to the logged data as I get the ai0 channel names across the top of the columns and not the names that I have put in.
Is there anyway of getting data like the attached snippet?
Many thanks for your help in advance.
Neil Barker, Redbull Technology.
Attachments:
Channel names.gif ‏4 KB

Hi Dan,
Thanks for the reply, that has certainly fixed my issue as I wasn't expanding the channel and selecting the channel that I had renamed.
One last thing though:
I now not only get the individual channel name but the prefix for the DAQmx Aquire, for instance I get the Input of Braketest and then the channels under the input data.
It looks a bit like this....
Braketest - Front Pres
Braketest - Rear Pres
Braketest - FR Temp
Braketest - FL Temp
etc etc...
Now all of the channel names at the top of the columns have this long name. Can this be rectified? can I remove the "Braketest" bit?
By the way I am saving it as an ASCII so that I can read it in excel.
Many thanks, Neil.

Power factor in signal express

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