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Lock-in Amplifier and DAQmx

Hello xthan,

You can use the lock in amplifier toolkit with any device as long as you pass it the correct data type (2D array of single precision numbers).  The library provided above uses DAQmx to acquire the data to pass to the toolkit, so as long as you use a device that is programmed using DAQmx you can run the example.

The 4461 is one of our DSA devices which are the type of device that this toolkit was designed for (and is programmed using DAQmx).  Your card should work quite well with the Lock-In Amplifier
Neal M.
Applications Engineering       National Instruments        www.ni.com/support
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Message 11 of 29
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Thanks Neal. My card is 4462, I think it is same as 4461 in applying DLIA toolkit.
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Message 12 of 29
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Xthan,

You are correct, the 4462 is the same in this situation.  It is also a DSA device and should work very well.
Neal M.
Applications Engineering       National Instruments        www.ni.com/support
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Message 13 of 29
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hi,Travis W,I am a freshman to the LIA.
I also have some problems when using the example" MultiChannelLockIn-DAQmx" you provided.
Running the VI,I get no results,the frequency is always 1.00,and the Y,X,R,Theto are all zero.I have check my connectors,and the input and reference signals both work on my Scope.
My card is PCI 6221(Can the card be used for the lockin amplifier?),and the software is labview 8.20.
 
Thanks,
Huangyao (my email box is yhuangstu@163.com)
 
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Message 14 of 29
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Hello Huangyao,

It sounds like you may not be acquiring your signal on your PXI 6221.  In order for the lock in processing to work, it needs an AC signal to work with.  If it is only reading a DC signal, you will get the readings you describe.  I confirmed this on my 6251 by reading a DC voltage.  To test this, take a look at step #9 in the DAQ Getting Started Guide.

Just for everyone's reference as well, here is the link to the Lock In Amplifier, and more importantly, here is the link to the DAQmx examples for it.  This is a link to an article describing what NI hardware (and some important features) works with the Lock In Amplifier.

Please let me know if there is anything else I can help you with.
Neal M.
Applications Engineering       National Instruments        www.ni.com/support
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Message 15 of 29
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Hi,Neal M,thanks for you help.It is really very nice of you.
Now,I have another problem.I am doing a test about the vibration,and I want to test the frequency of the vibration (supposing there is only a single frequency in the test),but as we know, the lock-in amplifier's output is usually a DC value,can it be used for my vibration test.If yes,how to make it or how to set the parameters?I know the setting is very important.
 
I have used the example"MultiChannel LockIn - DAQmx" to have a try ,but it seemed to not work quite well.
 
Your reply will be greatly appreciated!
 
Thanks,
HuangYao.
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Message 16 of 29
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Hello again Huang Yao,

I am not quite sure what you are trying to do.  The lock in amplifier is all in software, so it is not outputting a DC value.  Do you mean a number for the frequency?  If you want to turn this into an AC waveform, then you want to use a VI such as the Sine Waveform.vi (in the functions palette under Programming»Waveform»Analog Waveform»Generation).

Perhaps some screenshots of what you are seeing vs what you want to see would help.

Neal M.
Applications Engineering       National Instruments        www.ni.com/support
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Message 17 of 29
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For vibration test, you will want to use a FFT and assorted other scaling and filtering tools.  If you have standards you want to test to, you will want to consider the sound and vibration measurement suite, www.ni.com/soundandvibration
 
Preston Johnson
Solutions Manager, Industrial IoT: Condition Monitoring and Predictive Analytics
cbt
512 431 2371
preston.johnson@cbtechinc
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Message 18 of 29
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Hello everybody,

sorry to bring this up again but Im having trouble with the DAQmx lock-in application from NI. The PLL subvi keeps throwing out apparently random values for the phase. i dont know whether this is normal or it should somehow stabilize around a given value (since its called "lock"-in...). both the TLL square reference signal and the sine input are generated by the same function generator. Frequence range is 50 to 2000Hz.

 

thanks in advance

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Message 19 of 29
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Hi,

If this topic is still active. Does this lock in kit works for high modulation frequencies e.g. ~100Khz or is their any samppling issue with the PLL or Lock-in VIs at those frequencies.

Thanks.

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Message 20 of 29
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