DC offset problems in NI-5401 function generator card

When i give a Dc offset of 1 Volt the output of my function generator reads 1.97v. what is the reason behind this,why is it so what setting have to be made so as to get the dc ofset only when no ac signal is given.

Hi. The NI 5401?s output voltage is specified in terms of 50 ohms. This means for a 50 ohm load, you should see 1.0 Volts for a 1.0 Volt setting when the load is 50 ohms. For an other than 50 ohm load, there is a voltage divider action that takes place, where the voltage will vary up to double the size for a high impedance load, such as most default oscilloscope settings. The Connecting Signals>>ARB Connector section of Chapter 1 of the NI 5401 user manual describes this in further detail.
To generate just a DC voltage level, there is an option for DC as the Waveform to use when programming the device. The LabVIEW niFgen Function Generator Example shows this on the front panel. If you are using the Sources Soft Front Panel, when the Standard Function Output is se
lected, there is a DC Voltage level selection button available to be selected to generate a DC voltage.

Similar Messages

VB/C# Function Generator Example

Hello,
I have a NI-5401 Function Generator and a NI-5112 Digitizer for hardware. I would like to use C# to output a signal from the Function Generator to the Digitizer and see the results on the CWGraph control. Is there any sample (in Visual Basic if C# not available) that demonstrates the appropriate ActiveX controls and some basic functionality similar to this?
Thanks in Advance!
Derek

Hi,
You may want to take a look at the following:
C:\VXIpnp\WinNT\nifgen\Examples\VisualBasic
Sincerely,
Sastry V
Applications Engineer
National Instruments

NI ELVIS PROBLEM: Function generator DC offset

Hello
My ni elvis has a serious problem!
The func generator gives a 40mV DC offset when i try to generate a sinewave whitout offset!
Can you help me?
Thank you!
Giovanni

Hi Giovanni,
I verified the specifications of the NI-ELVIS and I noticed that the DAC of the function generator has a resolution of 8 bit and output range of (-10,+10) V.
Moreover in the version 2.0 of NI-ELVIS is possible to perform a calibration procedure (execute the Calibration Wizard) to improve the resolution of the signal generated.
I hope these informations can help you with this device.
Best regards,
Marco Lencioni

Problems with the Stanford Reseach Systems DS345 Function Generator

I'm writing a labview program that will allow operation of the Stanford Reseach Systems DS345 Function Generator. The problem that I'm having is in the amplitude calculation. The way the driver finds the amplitude is by recieving an array of what are essentially y-coordiantes (on a cartesian graph system), finding the max and min of the array, and subtracting them.
This is where the problem lies. I've designed my program so I can type in an equation, see the graph of this equation, and send the y values into a the subvi provided by the driver. This subvi is the one that finds the amplitude...etc and sends it to the oscilliscope. However, when I use a formula for something as simple as sin(x), it caclulates the amplitude as 2. This is because the max/min values of sin(x) are 1 and -1. So the function generator reads in an amplitude of 2. This amplitude of 2 results in a sine wave that oscillates between 2 and -2. Obviously, this is not what I'm looking for. I know by dividing the sine wave coordiantes by 2, or just using the max/min value to be sent to the function generator as the amplitude will work in this case, but not for all cases (ex: sin(x)*e^(-3x). I'd appreciate any suggestions on how to fix this amplitude problem for all cases.
In addition to having this sine function, I wrote a subvi that essentially generates a series of pulses depending on the user preferences. It's relativly complicated to explain how it works, but it just sends an array of y-coordinates (similar to above, and they are sent to the same subvi to be sent to the function generator). This array is the one that truly puzzles me.
For example, I have a single pulse, with height 5. The y array is 10 places big. At index 0 to 3, the y value is 0. At 4 to 6, the value is 5. And from index 7 to 9, the index is zero again (Imagine a pulse "_|-|_" , it may help understand this).
I send this array of 10 places to the same subvi as the one described in the sine function earlier. I would expect the amplitude to go in as five (max - min), and it does. However, when determining the actual value from the oscilliscope, it turns out to be 10.8 peak to peak voltage. The values range from -.8 volts to 10 volts. I can't imagine why they do not range from 0 to five as specified in the array which is sent.
If anyone has any answers, suggestions or questions concering this description, I would greatly appreciate it. Feel free to post answers or email me at: [email protected]
I'll be more than happy to post the files if someone wants to look at them.
Thanks again,
Jim Dalton
North American Lighting
[email protected]

I am taking these measurments using the measurment and automation explorer test function. I set my range on all channels to 0-8khz and Have been inputing no more than 8khz. What leads me to believe I have a software or config problem is that I sent in a module to NI for repair and this is the brand new one they sent me back. While testing this module, I also have a 1102 module and 1124 module on the scxi-1000 chasis and both of those are working as specified. I also moved the 1126 module to slot 1 and ran it that way as well when I replaced the chasis.

DC Offset problem with Peak 4.14 on MacMini after new hard drive upgrade

Tiger 10.4.11
Bias Peak 4.14 (24-bit 44.1 AIFF files)
USBPre 1.5
The reason for this new topic is a problem that developed with Bias Peak 4.14 on my MacMini. Suddenly, when I apply the "Remove DC Offset" DSP process to a recording, the Bias Peak meters may stop displaying correctly.
About 50% of the time, only one meter will respond to the sound, or neither will (the meters work fine on the raw file before I apply the DSP function). The rest of the time, they work normally after DC Offset. I'm still waiting to hear from Bias about this via their forum, but no-one has responded yet. I don't know if this is just a GUI bug or an indication of a recording problem. The really spooky thing is that the problem only shows up part of the time.
This is happening on a new installation of OS X on a new drive that I installed. See a note at the bottom of this post for a hardware issue that may or may not play a role.
I've been recording vinyl successfully for a long time now on my MacMini (24-bit 44.1 AIFF), using a USBPre external A/D converter and Bias Peak (currently v4.14). But recently Peak froze as it was saving a file. I had to do a hard shut down which led to a corrupted system. I'd been meaning to upgrade to a larger drive anyway, so I put a 120 gig drive in.
After first installing/updating OS X on the new drive, and installing/upgrading Bias Peak, I had no problems. But then the control panel for the USBPre froze as I was getting ready to shut down. This worried me, so I ran diagnostics with TechTool and installed eDrive. The meter problem began showing up after this change. I wiped out the partition and reinstalled from scratch again, hoping that this would get things back to normal. But I still have the meter problem after applying DC Offset. Note, I created two partitions on the drive, and put Tiger on the first partition.
The makers of the USBPRe (Sound Devices) say there is nothing about the USBPre or drivers that should be causing this.
So I'm stuck, and faced with the following ideas for what might be wrong:
1. Peak has a bug that I've somehow triggered. This may or may not be affecting the recording.
2. Something about my recording hardware/driver has changed that is "corrupting" my recordings sometimes, and this is causing Peak to have trouble metering the sound.
3. I screwed up my computer hardware and this is screwing up the recordings part of the time. See my upgrade note* about the hardware.
4. The new drive seems to be a little slower to display folder contents. I wonder if this apparent latency could be causing the DC Offset problem in the original recorded file.
* Upgrade note: When I tried to put the cover of the Mini back on after upgrading my drive and testing it out, I discovered that I hadn't screwed the drive/fan/DVD setup in correctly. The screws had fallen out and disappeared (my tiny screw driver made it very hard to tighten the screws I guess. I thought I’d done it correctly).
I turned the Mini upside down a couple of times before I discovered the screws missing.. My first attempts to put the cover on with the Mini sitting upright were not successful, so I turned it upside down to take the cover back off. The screws probably fell out then. When I tried putting the cover top down on the table and lowering the Mini into the cover I discovered that the drive/fan/DVD assembly was loose!
The drive is now secured completely except for the screws, and it is working. The slowness I mentioned above is something I noticed before the screws fell out, but obviously the assembly was not secured 100% even before I lost the screws.
I apologize for this convoluted post and hope it is clear enough. Please help if you can, I'm under pressure to finish my recording project.
Vinyl_Man

Hello, DaddyPaycheck,
The USBPre is powered by the USB bus, and it is plugged directly into the MacMini.
The screws remain in hiding. I'm amazed that I didn't find them on the motherboard or something like that. If they don't turn up fairly soon, I'll try to get replacements from an Apple service center. And I'll make sure I have a better small screwdriver.
I just did a test with Audacity for OS X and Cool Edit for Windows. I opened files that give me the meter problem in Peak and removed the DC Offset. When I opened the files I had modified in Audacity and Cool Edit, Peak metered the sound correctly. Somehow Peak is sensitive to something in the file that does not bother the other apps, and when the other apps have adjusted the DC Offset, Peak is happy. Peculiar.
I'm thinking about recording with Audacity now instead of Peak. I'm still concerned that something is wrong, though, since I don't understand the problem.
-Vinyl_Man

Time offset problems with file i/o

Hello everyone, I'm having a problem with the file i/o VI's. I require my application to save serial data at constant five minute intervals. The problem I'm currently seeing is that on each save to a file a time offset is being added which eventually becomes seconds, then minutes and so on. Since this application is meant to be run for a whole year this is a serious problem.
Attached is the VI, an Arduino program simulating how the DAQ sends data and a file showing my time offset problem.
Any ideas/suggestions/fixes are appreciated.
Thanks
Jose Molina
P.S.
To run the VI upload the code to an Arduino, select it's serial port in the popup VI then click on Ok. The VI will wait for a time that is a modulo of 5 then create a folder structure inside the same location as the LLB. Inside this folder structure should be a file with the data which should be saved every five minutes if left at the default averaging time.
Attachments:
7-8-2012.txt ‏3 KB
Daq_Simulator.zip ‏1 KB
Weather_DAQ.zip ‏117 KB

Sorry I forgot to mention that the averaging time is configurable in the pop up vi at the start. I tried 20 seconds because it's much faster for testing than 5 minutes. Timing is being done by a simple counter that increments each time data is received. So if I receive data the timer increments by 5 because data is sent every 5 seconds. Once the timer is equal to the averaging time the data is sent to the enqueue function and then the blocking dequeue function on the second loop sends the data to the file save vi which then saves the data to the file.
Attachments:
counter.PNG ‏13 KB

Elvis: Is It possible to use the Function Generator and the Oscilloscope simultaneously?

Hi,
We are using the NI Elvis to output a function or a sine wave at a certain frequency and using the oscilloscope on the same board/elvis to read a modified signal. Is this possible? Can we use both the Function Generator and the oscilloscope at the same time? Please help. The oscilloscope would be reading signal from an accelerometer. Thank you in advance. We have no VI as we do not know which to use and if they are possible.

Hi,
There is no problem using the Function Generator and Oscilloscope
at the same time with NI ELVIS. Using the NI ELVIS soft front panels (Start
>> Programs >> National Instruments >> NI ELVIS 3.0 >>
NI ELVIS – see picture attached –‘NI ELVIS soft front panels.JPG’), you can choose
to open more than one instrument at a time. We do this by opening one
instrument, allowing it to begin, and then opening another. We can also program
in LabVIEW using more than one instrument at a time by placing down multiple
Express VI’s taken from the NI ELVIS pallet on the block diagram (see picture
attached – ‘ELVIS Express VI's (LabVIEW).JPG’). One note when doing this,
please see KB 41ODPHX1
for an example of how to program in parallel. If you do not wire the ‘stop’
terminal of the express VI’s, you will get the error described.
David L.
Systems Engineering
National Instruments
Attachments:
ELVIS Express VI's (LabVIEW).JPG ‏74 KB
NI ELVIS soft front panels.JPG ‏56 KB

Create a melody with Labview/ Function Generator

Hi (first sorry for poor english, not my native language)
I have a project at school which is creating a melody using Labview and a function generator. I've worked on it for hours now and i still can't get through it.
I joined the vi file with my post so you can get a look at what i've done so far.
First, i do'nt know which loop i have to use (u'll understand soon enough if u just take a look at the vi file), the problem is that i want to create 4 arrays using 2 text files.
The first one is used as a reference : exemple the frequency to play an A is 440Hz, so my first text file looks like that :
A 440
B 493
the second one is my melody, which includes the notes and the tempo (in ms)
, so it's like :
B 1000
C 1500
I used the first two loops to seperate each string lines of my files so I have at the end 4 different arrays. One containing the note's references, one containing the frequency, one containing my melody's notes and one containing the duration of each notes.
The problem is that when I use a while loop, it seems that my arrays are not containing every elements it should, it only has the last one. Just try to run the vi file.
Could anyone give me some help ? Don't hesitate to ask more questions if u didn't fully understand my problem !
Thx
Attachments:
PR.vi ‏19 KB

Hi claudeuntel,
Your array contains just the last note because at each for loop iteration a new table is created.
You have to send the table you created at one iteration to the next one.
To do this you can use shift register.
I didn't have tested the VI below but it should looks like that.
Valentin
Valentin
Certified TestStand Architect
Certified LabVIEW Developer
National Instruments France
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Travaux Pratiques d'initiation à LabVIEW et à la mesure
Du 2 au 23 octobre, partout en France

ESB problem when use merge function in master/detail relationship

I have some problem with the merge function in database adapter.
details:
I have 2 tables in master/detail relationship, both have GUID column as a primary key (GUID generated by ESB).
'car_group' table
pk : guid
unique : group_no, datadate, datatime
===============================
guid, group_no, datadate, datatime, group_detail
===============================
1, 1, 01/01/2008, 09:00, groupdetail01
2, 1, 01/01/2008, 10:00, groupdetail02
'car_group_detail' table
pk : guid
fk : car_group_guid link to car_group.guid
==================
guid, car_group_guid, detail
==================
1, 1, detail01
2, 1, detail02
3, 2, detail03
4, 2, detail04
I used a file adapter as a input, here is an example text file
M, 1, 01/01/2008, 09:00, groupdetail01
D, detail01
D, detail02
M, 1, 01/01/2008, 10:00, groupdetail02
D, detail03
D, detail04
Because I used merge function so I need to specify the columns that will be a condition for the insert/update,
but I have generate GUID as a primary key in the tables, I can't used it, so in toplink I map my unique key as a primary key.
The insert operation work fine but when update is required (for example, try to change 'group_detail' column of the master table in text file),
an SQLException thrown, the log file shown the adapter try to update the GUID column of master table but the constraint not allowed.
And yes, cause of GUID generate everytime so ESB try to update this column also, but I don't want to do like that, I need something
like when update operation required, just ignored the GUID column.
I try to mark read-only to the GUID column in Toplink mapping file but still have the same problem, it still generate UPDATE statement
with the GUID column, and also I try to let the database trigger to generate GUID instead of ESB function, but it not works in master/detail
relationship (I think the Toplink manage the relationship, is it right ?)
Please advise, thanks for advance.

somebody please help, thanks !!!

Proportional controller connected to a function generator

Hi....
We'd like to connect some output from a proportional controller to a function generator which
produces a square pulse with variable duty cycle.
The question is what proportional controller to use here and if there is any examples related?
And how to produce this square pulse with a high frequency, while some controllers do not support
any thing more than 1kHz? In addition, if it exceeded this, something wrong happens to the output and disappears?
Thanks in advance
Ray

Ray,
Please be more specific in your description. Proportional controllers usually do not connect to function generators so it is not clear exactly what you are trying to accomplish.
Which parts of your system are hardware and what kind? Which are implemented in LV (which version)? What are the inputs and outputs to both the hardware and software? What frequency range do you need? If you have specific problems with a part of your LV program, posting an example showing the problem is very helpful.
When you say the output disappears, do you mean that the pulses stop? That may simply indicate a 0% or 100% duty cycle.
Many inidviduals with a wide range of experience monitor this forum and will try to help if we understand what you are trying to do.
Lynn

Hp 3311 A function generator GPIB

Hi, I've a Hp 3311 A function generator and I'd like to control it by GPIB. I'd tested with the example in labview "GPIB.vi" but when i send it a command, pej "APPLIN 1.0E+3, 3.0, -2.5" it doesn't work (It makes only a sound "Bip" ).
Does anyone knows why the function generator doesn't generate the signal?
Note: When i send it the command IND?, the instrument returns the name "Hp 3311A", but when i send another command it doesn't work.
Thanks. Regards, peliasrojo.

Hi. I don't use the drivers, I'm using the example GPIB-VISA. I'm be able to change the type of function (sin, square, etc) but when i try change the frequency or the others parameters it doesn't work.
I've attached the program (v2011). The program only tries to apply a square signal with visa commands.
The manual shows an example of a sine function: "APPLIN 5.0E+3, 3.0, -2.5" that generates a sine function of 5kHz, 3Vpp and an offset of -2.5V.
Thanks, regards Peliasrojo
Attachments:
GPIB-VISA (modificada).vi ‏11 KB

Creating two sin signals using function generator.vi example

hi all. i want to create two sin signals with different parameters using function generator.vi example. i tried to modify the example by copying the code and try to output two sin signals on different channels of the DAQ but error message saying that you are validating of the AO write buffer . attached is the file. how can i modify it to solve the problem?!
Attachments:
function_generator2.vi ‏123 KB

Nidal,
Below is an example that illustrates how to generate different sine waves on two separate analog output channels.
Example

How to plot data from a GPIB function generator

I am doing a litle application with Visual C++ and the ComponentWorks++ to
control a GPIB device. I am tring to Plot a CNiGraph with data coming from
the GPIB function generator. I use the code below to write/read the device
and to Plot the graph. It give me some results but for exemple, if I
request a sin wave it give me something that doesn't look like a sin and if
I request a square wave it give me about the same wave... So I want to know
if the problem is in my code or maybe it's because my device is just a
emulator not a real func generator. But I guest I am doing some kind of
convertion error.
CNiInt16Vector vBuffer(100); // Should I try CNiReal64Vector or something
else ?
m_Visa->Write(m_strC
ommande); // Write to the device, this works well
m_Visa->Read(vBuffer); // Is it the right way to do reading ?
m_Graph.PlotY(vBuffer); // This Plot some data, but it doesn't seem right
Could somebody bring the light on this?
Thanks alot!
P.S. Sorry for the bad english...

Ares:
I have two suggestions about common problems in VISA.
(1) How is m_Visa defined? There is occasionally some confusion about which VISA class should be used for this purpose. CNiVisaSession is the class designed for this purpose.
(2) How is the instrument returning data? Usually instruments return some sort of header before the actual data.
You may want to contact National Instruments Technical Support to continue this discussion. You can reach our telephone support at 1-800-IEEE-488 or email support at http://www.ni.com/ask.
Good Luck,
Chris Wood
Applications Engineer
National Instruments

Acquire waveforms from function generator to oscilloscope

I have a problem. We constructed a virtual function generator and a virtual oscilloscope. It's working well, the oscilloscope is displaying the (almost) correct data. My problem is that the waveform displayed in the oscilloscope vi is always sine, although the selected waveform in the function generator is already different.
I should replace the constant 'zero' with something so that the cases will change in order for my oscilloscope to display different waveforms. Is there a way to acquire the values of the constant enum, for instance, from another vi to this vi?

Yes, you would need to replace the constant with a control. Once you do this, in the main VI you simply do a right click on the subVI's terminal and select Create Control/Constant that but you cannot change it as the subVI runs.

Linking function generator to AM modulation toolkit

Dear
I am doing an AM modulation demodulation telecom project using labview.
I have in attachment the function generator (as the message signal) and Am-modulate (as AM modulation process) but I am facing problem wiring the function generator as the message signal in the AM-modulate. I would be thankful if someone can help me doing so. Moreover if you have any idea how to perform the demodulation process using MT modulation toolkit I will be thankful.
Thank you for your help
Solved!
Go to Solution.
Attachments:
Function-generator.vi ‏40 KB
AM-modulate.vi ‏30 KB

Hi o4enPro,
Thank you for contacting us
I replied you here: http://forums.ni.com/t5/LabVIEW/MT-modulation-toolkit-problem-Am-modulation-demodulation/m-p/1571542 for the demodulation issue. Was it helpful?
Modulation process:
You have more opportunites to connect the signal output of the generator to the modulator VI.
- Using global variables: In this case you have create a new project and create a global variable. The generator VI should write the global variable and the modulator VI should read it. You should run both VI at the same time.
- Embed the generator VI into the modulator VI. I attached an example. You should insert the generator VI (on the modulator block diagram: Functions Palette -> Select a VI). The generator VI's connector pane should be edited, you should make the input and output connections of the VI, so prepare it for using as SubVI.
Please find the attached VIs for example. The main VI is the AM-modulate_modified.vi, so you should open just that. If you have any questions, write again.
Regards,
Peter
Peter Vago
AE Hungary
Attachments:
AM-modulate_modified.vi ‏36 KB
Function-generator_modified.vi ‏50 KB

DC offset problems in NI-5401 function generator card

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