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Hifrequency
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How can I generate high frequency signal from NI USB 6251 and modulate that using HP AM modulation unit?

Hello guys,

 

I have a two-step question. 

 

Firstly I am interested in generating sine wave from USB 6251 

Then to modulate that signal in HP AM Modulation unit

 

Eventually I want to modulate a chirp signal instead of a simple sine wave and modulate that in HP unit. 

 

Any suggestions? Even links to tutorials/other messages in this NI forum would help.

 

Thanks! 

Member
MissFitt
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Re: How can I generate high frequency signal from NI USB 6251 and modulate that using HP AM modulation unit?

Hello Hifrequency,

 

I'm attaching an example that can be found in the NI Example Finder under Hardware Input and Output->DAQmx->Analog Generation->Voltage. This is an example about how to generate a sine wave from a DAQmx device. 

 

Regarding modulating the signal with the HP AM Modulation unit, can you tell me what unit you plan to use? Since I don't have documentation regarding the HP device, I would suggest looking in the manual for the unit or trying to find examples from them. 

 

Hope this helps!

 

Mychal F

Applications Engineer
National Instruments
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Hifrequency
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Re: How can I generate high frequency signal from NI USB 6251 and modulate that using HP AM modulation unit?

Hello Mychal,

 

Thank you for the code.  I appreciate it. 

 

However, I wasn't able to run the code in LV 8.0

 

Can you please tell me what LV version you made the code? 

 

I also wanted to try running the code through Labview SignalExpress. 

 

In the Labview SignalExpress I have, I can run LV 8.2, 8.5, 8.6, 2009 and 2010. 

 

I wasn't able to run your code in Labview SignalExpress either. 

 

Thanks again!

Member
MissFitt
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Re: How can I generate high frequency signal from NI USB 6251 and modulate that using HP AM modulation unit?

Hello Hifrequency,

 

That code was made in LabVIEW 2010. I didn't realize you were using LabVIEW 8.0, I apologize for that. Before I save this code back to the older version of LabVIEW, I need to know if you have the DAQmx drivers or the Traditional DAQ (Legacy) drivers installed. You probably won't be able to run this code in Signal Express so I will look into finding something else for you! Thanks!

 

Mychal F 

Applications Engineer
National Instruments
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Hifrequency
Posts: 10
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Re: How can I generate high frequency signal from NI USB 6251 and modulate that using HP AM modulation unit?

Hello Mychal,

 

I appreciate your time and efforts. 

 

To answer your previous question, I'm interested in connecting NI USB 6251 to HP 33220 AM Modulation unit. 

 

I found this link on NI website helpful: 

 

http://sine.ni.com/apps/utf8/niid_web_display.download_page?p_id_guid=0470714759413BCCE0440003BA7CCD...

 

Just to reiterate I want to generate a signal in NI USB 6251 and modulate that in HP unit. 

 

The link indicates that I have to install a plug and play driver.

 

However, I'm not sure how to interface the HP with NI system.

 

I am able to interface HP with a basic function generation using BNC input to HP unit.

 

However, I am confused with the NI 6251. How will I be able to interface the NI with HP?

 

Thanks for your help!  

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MissFitt
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Re: How can I generate high frequency signal from NI USB 6251 and modulate that using HP AM modulation unit?

Hifrequency,

 

I looked at the manual for the HP unit, and it seems that in order to directly interface with it, you will need to connect it to your computer via USB or GPIB.

 

The NI-6251 is not a GPIB or USB controller. Therefore, you will need to connect the Analog Out of the NI-6251 to the HP units input (use a BNC to two wire cable). This will allow the NI-6251 to generate your signal and will also allow the HP unit to read the signal. However, in order to control the HP device, I see from its manual that you will need to connect it directly to the computer via USB or GPIB. Then you can use software (either software that came with the HP device or LabVIEW with the HP drivers you linked to) to interface with the HP unit.

 

You can use Signal Express to generate the sine wave with the NI-6251 but you won't be able to do any data manipulation (or use the HP unit) in this software. I would suggest using LabVIEW for the whole project. You can generate the signal using the examples that I showed you how to find and then use the driver that you download to communicate with the HP device.

 

Hope this helps!

 

Mychal F

Applications Engineer
National Instruments
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Hifrequency
Posts: 10
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Re: How can I generate high frequency signal from NI USB 6251 and modulate that using HP AM modulation unit?

Excellent! 

 

Thank you so much Mychal. 

 

However, I don't know how to connect the Analog Out of NI-6251 using BNC. That was one of the things I stumbled upon yesterday. I don't see a BNC or any other port on my 6251 and I didn't want to open it until I know how it is done. Is there any tutorial on how to access the Analog Out of NI-6251 and then use a BNC? Or if it is easy then would it be possible for you to briefly explain the steps? Thanks a lot. 

 

My other question is, which LabVIEW version would you suggest to use for the purpose of communicating with the HP unit? I currently have LabVIEW 8.0, but I can purchase higher versions if those would be useful for this. Please suggest. 

 

Thank you for your time. 

 

 

Member
MissFitt
Posts: 78
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Re: How can I generate high frequency signal from NI USB 6251 and modulate that using HP AM modulation unit?

Hello Hifrequency,

 

I'm glad that helped! Connecting your 6251 depends on which analog out you want to connect to. If you look at the device specifications which I have attached, you can see what pins are analog out and use the pin diagram to connect to your device. I would also suggest using a BNC to two wire cable to connect to the BNC port of the HP device. If you Google "BNC to two wire cable" the image that pops up is what I am referring to. 

 

LabVIEW 8.0 is a pretty old version, so if you have the resources, I would suggest upgrading. We recently released LabVIEW 2011 and with each released version, new features are introduced. You can see some of the new features of LabVIEW 2011 here. Hope this helps!

 

Mychal F

Applications Engineer
National Instruments
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MissFitt
Posts: 78
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Re: How can I generate high frequency signal from NI USB 6251 and modulate that using HP AM modulation unit?

It would help if I attached the specification sheet! Sorry!

 

Mychal F

Applications Engineer
National Instruments
Member
Hifrequency
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Re: How can I generate high frequency signal from NI USB 6251 and modulate that using HP AM modulation unit?

Thanks Mychal. 

 

I opened up the shielded mass termination unit and I was able to identity the AO pin. 

Now my question is, why do we need two wires? Will I need to solder the wire to the pin? 

Where exactly do I connect the wire which I don't connect to the AO pin?

I'm sorry if you find my questions too naive. I haven't done this before and want to be sure before I do it.

 

Regarding LabVIEW, I will purchase the 2011 version.

Is it available on NI website or do I have to go to a store?

Also do you think this 2011 version will be compatible with HP unit?

 

I am going to check if I can get the BNC to two wire cable at radioshack, if not, then I will order it online.

 

Thanks for your help!!