Lock-in Amplifier and DAQmx

I've downloaded the NI Lock-in amplifier toolkit (llb file), and I have
a PXI-4472 board. The toolkit looks to be based on traditional DAQ, not
DAQmx. Did I miss the DAQmx version, or has no application engineer
posted one yet? Please let me know if there's a timesaver out there
before I just start to convert it on my own.
Thanks,
Rob

Thanks. That version doesn't work with LabView 7.0, by the way. I had a tech support person email me with a version that would.
Here's an update from my end: I have it setup and running. Only, it seems to burp at the PLL sub-vi. I KNOW that have the correct data going into that sub-VI and that my DAQ board is working b/c I've put probes and indicators in the path and such. The problem is that it doesn't calculate the correct reference info. If I place a probe at the "reference info" output, it returns a constant output of fr=1 and phase =0. This is bizzare. I've changed every parameter I can think of (sampling rate, block size, offset parameter, column value, time constant, etc.) but it yields no positive result.
Any ideas or suggestions? I'm at wits end.
BTW, my board is the 4462, not the 4472 I mentioned previously. And, my refrence signal is a TTL square wave from 0-4 Volts, operated anywhere from 10Hz to 2KHz. That's working correctly as shown by my scope. But according to the PLL VI, it is always 1 Hz!
Thanks,
ROB M.

Similar Messages

Lock-In Amplifier and offline data processing

Hi everyone,
I've been successfully using the Lock-In Amplifier to do live data processing. The processed Lock-In outputs and the frequency values are then saved. Recently it has turned out that the real acquisition capabilities needed mean that online processing is not possibe. (As 4 channels are being simultaneously sampled each at 4Mhz and acquiring for several seconds.) I have built the Lock-In Amplifier into an offline processing VI where I strip out the arrays for Channel 0 (Signal) and Channel 1 (Reference) and send chunks of data to the Lock-In. I wanted to check that the Lock-In doesn't have any problems working offline? Are there any other things I need to know for offline processing?
Many thanks

Hi,
I've not personally had the change to use Lock In Amplifiers with our hardware yet, but from searching through the LabVIEW developer zone I came across this example VI, I hope it's some help to you: http://zone.ni.com/devzone/cda/epd/p/id/4532
All the best,
Applications Engineer

Does Lock in amplifier kit work with DAQpad 6016

Hi all,
I have DAQPad 6016 (USB). I am trying to develope Lock in amplifier and I found Lock in Amplifier start up kit. So I am wondring that this tool kit works wit DAQ 6016? Moreover, DAQ 6016 does not support treditional DAQ. And this tool kit is with traditional DAQ so Can i change this traditional DAQ to DAQmx or any update available for Lock in amplifier start up kit?
Thank You

Hi N.K.,
I found an example which is using DAQmx. Have a look at:
Multi Channel Count Lock-In Amplifier with DAQmx
http://sine.ni.com/apps/we/niepd_web_display.display_epd4?p_guid=042319214C65627AE0440003BA7CCD71&p_...
Also please look here, because I the 6016 does sampling not simultaneous!
Lock-In Amplifier Startup Toolkit Compatibility with Non-DSA Hardware
http://digital.ni.com/public.nsf/websearch/EBAADBD271ADFEC586256C86007B63F9
Regards,
Andi
~~~ Logic is a systematic method of coming to the wrong conclusion with confidence ~~~

Implementing a Lock In Amplifier using a PCI-6034E DAQ card

I am looking for a lock-in amplifier and have read about the Lock-in Amplifier kit provided by NI. I am wonder in is it possible to implement a solution with a PCI-6034E DAQ card instead of the 4472? And if so what would be the limitions of using the 6034 for this application?

The requirements for the Lock In Amplifier are contained within the document linked bellow. The S series can be used with the Lock In Amplifier but not the E-series.
http://ae.natinst.com/operations/ae/public.nsf/fca7838c4500dc10862567a100753500/ebaadbd271adfec586256c86007b63f9?OpenDocument
Regards
Jon Bowers
Applications Engineer
NIUK

Connecting lock-in amplifier to USB-6009/6211

I am working on re-setting up a labview environment in the lab I work at. We are using a SR810 DSP lock-in amplifier and want to bring the data into labview. The labview code says that in the past we used a USB-6009 to read in data from the lock-in amplifier. The output ports on the lock-in are an RS232(DCE), a IEEE-488 port, and a preamp port. Is there someway to feed one of these outputs into the DAQ that we have. Thanks

An RS232 or GPIB connection directly to the computer would be best, but if you insist on using the 6009, run a line from the CH1 outut BNC on the front panel of the lockin into the DAQ device. Note that this is a -10 to 10 V output and that the mapping to the actual LIA voltage depends on the sensitivity setting of the lockin (see pgs 4-2 and 4-12 of the 810 manual).

Set values for the Lock-In Amplifier's Digital Analog Converter Channel?

If I let my user have the freedom to select whatever values they want to select in order for it to show up as the output value for the Digital Analog Channel then I cannot understand why use ibwrt(...) and ibrd(...). Because ibwrt is going to write a specific voltage at the specified channel since the manual for the Amplifier states you must input the string for writing output voltage as DAC2 3000 (the 2 signifying the channel and 3000 - the millivolts). If this hard coding occurs by using ibwrt then how can I write my code so that the user has the capability to change the voltage value and the channel to the one they want? Thanks in advance.

Do I need a Fmt and ibwrt for both DOutput and VOutput? Because DOutput is indicative of the channels 1, 2, 3, 4 in the Lock in Amplifier and the VOutput is for the amount of volts the user can set (i.e. write to the instrument). Also I found this on the following NI website regarding filling in the value of the write buffer: Write Buffer Value. This website signifies that one must use \002 and end with 003\ which I am not sure I even need for this instance of initializing the writeBuffer[8]. Also I used [7] for the writeBuffer because I thought arrays went 0, 1, 2, 3...so on therefore writeBuffer[7] will give me space for 8 bytes? Is that an incorrect assumption? Lastly, here is my modified code according to the changes you mentioned and it still is giving me Non-Fatal Run Time Errors and not communicating. Is there anything else I am missing out on which I can't find. Seemed like I may be making this code much harder than it needs to be. Thank you for your time.
Sincerly,
Attachments:
SETDAC.c ‏2 KB
setdacwin.h ‏2 KB
setdacwin.uir ‏3 KB

Problems with LabVIEW 7.1 and lock-in amplifier Stanford SR530?

Does has anybody had problems with LabVIEW 7.1 and the instrument driver for the lock-in amplifier Stanford SR530?
With LabVIEW 6 there are no problems at all, but with LabVIEW 7.1 it is impossible to communicate with the instrument.

amr_attia wrote: (Private message, no need to private message)
My problem is to get the data out from the divice x and y readings . Can you help me
Here is the code and snippet. I had it from before. It reads Channel 1 and Channel 2 from the SR530, that is whatever the display is for Channel 1 & 2. You set the display manually or programmatically, I let you figure that part out.
Cheers,
mcduff

How to use lock in amplifier start up kit?

Hi,
I am now given a project which is Frustrated Total Internal Reflection (FTIR). Basically there is a lot of way to extract the information signal from IR sensor like DC approach, AC approach, transimpedance amplifier. I found that Lock In Amplifier is suitable for me to use in my project because the voltage across the IR receiver part will be small like mV and the noise will be high since the ambient light or sun light able to disturb the light wave emitted from IR emitter. Currently i download the NI lock in amplifier VI and i try to translate into DAQmx version. The VI can run but I am not sure that VI was translated correctly or not. Can just help me to check it out? Now I am using NI USB6366 to do the lock in amplifier as well. Here are some questions that i want to ask:
1. From the NI lock-in amplifier start up kit user manual, for the configuration section on PAGE 13/20, I found that the first channel in the channel list should be used for the signal and the second channel in the list should be used as the reference input. I am confusing with this because i just able to create a channel for acquisition puspose and the channel is used to wire the input of DAQmx start.vi. May I know another channel where should i put?
2. If USB 6366 able to use with lock in amplifier VI, how to acquire the signal from the IR receiver? I wire the A0+ to anode of IR emitter and A0- to cathode of IR receiver, is it correct? this wiring is used for the signal or the reference input?
3. The generation of signal to IR emitter also can be done inside the lock in amplifier start up kit? As i saw the signal generator function inside there but I am not sure what the function is.
4. lock in amplifier able to amplify my IR receiver's signal? or I need to build up a new circuit to amplify my signal then just feed it to the lock in amplifier VI?
Thanks for all the reply. Really need help on this. thanks
Attached will be my modified VI for NI lock in amplifier start up kit.
Attachments:
lock in modern.llb ‏460 KB

Claudia,
thanks for the version mentioned.
I would like to change the lock-In to one with a reference signal
instaed of PLL, and a few other changes.
I tried to understand how your sample works , but as soon as I'm
reaching the VI's on a deeper level I'm running into code protection.
Why are these VIs not public?
Thanks
Urs
Claudia schrieb:
>Hello,
>
>Another person was also asking for a Lock-In Amplifier Start-Up kit
>that would not expire, and I published it in the following Discussion
>Forum:
>
>href="http://exchange.ni.com/servlet/ProcessRequest?RHIVEID=101&RPAGEID=135&HOID=506500000008000000...
>
>Hope this helps,
>
>Claudia Lorente
>Applications Engineer
>N
ational Instruments
>http://www.ni.com/ask
>
>

Lock-In amplifier capabilities

Hello,
I am using the Lock-In amplifier start-up kit. I generate an output waveform and get 2 inputs back - reference and measured signal.
I connected the output with a coax wire to the 2 input channels (using BNC-2120) in order to test the program and the results aren't good. When I increase the frequency of the waveform the results even get worse (up to 1000 Hz needed).
I am using PCI MIO-16E-1 (PCI 6070), max reading rate 1.25MSa/s, and I understand that the start-up kit was written to much lower rates. I have another DAQ card PCI-6143 which has A/D converter for each channel (I think) but do not have analog output. I thought about using this one as input only and the first one as output, but I don't know how to do it (need RTSI cable?)
I have 3 questions:
1. What is the best configuration for my purpose, 1 card or 2 different ones? (also available to me PCI-6154)
2. How do I synchronize 2 different cards?
3. How can I find the optimum input and output rates? What are the limitations (min/max requierments) of the Lock-In amplifier? Is it possible to see the censored parts?
I am using LabView8.0
thank you,
Noam.

Hi Noam,
Without the PCI-6154, the best way to proceed will be to use a RTSI to synchronize the simultaneous sampling card with a card providing the analog output. The simultaneous sampling is essential for the lock-in amplifier. Additional reasons why this would be the best solution can be found in this article. There are examples in the Example Finder which show how to share the sample clock and a start trigger between the two cards. Instead of looking under Hardware Input and Output » DAQmx » Synchronization » Multi-Function, check under Hardware Input and Output » DAQmx » Synchronization » Multi-Device. There is also good information about synchronization and related topics such as signal routing across RTSI in this article.
The rates of both the analog output and input will be the same since you are sharing the sample clock. One thing to check is to make sure that the rate is at least twice as high as the highest frequency that you will be testing. It is not a bad idea of start off with a high rate to ensure that the sine wave that you are generating is smooth.
The error that you are seeing is a common overflow error. While you do not have to increase your buffer size to solve this error, you may have to read faster. The buffer size is different than the number of samples you acquire each time you call the DAQmx Read function. The number of samples to read each time can be changed by wiring a different value to the DAQmx Read function. If both of these values are set, then the way to make sure the buffer does not overflow is to call the DAQmx Read function more often. This will require making sure that there is nothing in the loop that is slowing it down. This may require moving all processing functions to a separate loop. There is more information on this error in this article.
Regards,
Kent
Applications Engineer
Digital Multimeter Home

Lock-in amplifier uncertainty

Hi,
I am using a NI labview lock-in amplifier, "Multichenel locl in-DAQmx", to read AC signals from 50Hz to 500Hz. Now I want to know how acurate the phase and amplitude are, or to say the uncertainty of the lock-in amplifier. My card is NI PCI-6035E and I am using labview8.2. The lock-in amplifier is download from Download the FREE NI LabVIEW Lock-In Amplifier Start-Up Kit last year.
thank you,
Nan

Hi Nan,
As the lock-in amplifier toolkit is
purely software, the only inaccuracies you need to worry about are those of the
board being used in conjunction with the lock-in amplifier. The specifications
for your PCI-6035E can be found in the NI
6034E/6035E/6036E Family Specifications manual.
Please post back if you have further
questions.
Mark E.
Precision DC Product Support Engineer
National Instruments
Digital Multimeters (DMMs) and LCR Meters
Programmable Power Supplies and Source Measure Units

SR510 Lock-in Amplifier Repeated Data Output Command Problem

Hi,
I'm using LabVIEW version 7.1 with an SR510 lock-in amplifier connected through GPIB-488.2. I've gotten past most of the hurdles, the device appears in MAX and I can send and recieve data using the VISA test panel. My main goal is to be able to have a VI where I am continuously asking the SR510 to output a voltage number while the data recieved is then saved in a .txt document and graphed as a function (simple x-y). The issue I am having is that the SR510 will not take more than one "q" command to output data. I can clear the settings of the lock-in with a "z" command, and then give it a "q" command and it will output correct information but if I try to run it continuously I get an error. I've tried using variations of the same "q" command (e.g. adding a needed carriage return, \r, \n) but none of them produce any different results. I should also mention that this issue only occurs with the "q" or output data command. Other write/read commands can be issued multiple times in rapid succession without any issues. I would be greatful if anyone had any advice as to why this might be occurring. Also I apologize if some of my terminology is incorrect as I was only just introduced to LabVIEW a few days ago.
Thank you for your time,
Sal

If you are brand new to LabVIEW, I would recommend looking at the VISA/GPIB shipping example to familiarize yourself with the different functions and how they interact. Go to Help»Find Examples... to open the example finder. The GPIB example is located in Hardware Input and Output»VISA»GPIB-VISA.vi.
When you say " I can clear the settings of the lock-in with a "z" command, and then give it a "q" command and it will output correct information but if I try to run it continuously I get an error." do you mean that you try and continously give it a "q" command and then a "z" command and it errors, or you just give it a "q" command? It may be possible to alternate between a "q" and "z" command inside a while loop to continuously output and then clear the settings and output again. It may also be that this device is not capable of continous output. I would check the user manual to see if this kind of operation is possible, and if so how to accomplish it. Let me know how it goes and if you have any more questions.
Regards,
Chris L
Applications Engineer
National Instruments
Certified LabVIEW Associate Developer

Driver disturbs lock-in amplifier?

The LabVIEW driver for the Stanford Research Systems SR830 Lock-in Amplifier, downloaded from the NI web site, does not produce accurate readings of the measured voltages(Channel 1 or Channel 2). It appears the phase has been offset, but no offset was programmed into the device, and the values fluctuate. When the device is programmed either from its front panel, Visual Basic, or other languages under the same conditions it produces accurate results. Can you identify and correct the bug in this driver?

Hello-
Be sure the display and output and ratio settings for each channel are apropriate. If this doesn't help, would it be possible to list the values are being used for the SR830 Example.VI? It's probably easiest to enclose a screenshot? Also, please state the expected return values from the instrument (possibly a sample from what VB returned).
Randy Solomonson
Application Engineer
National Instruments

Controlling a lock-in amplifier with labview

Hi there, Does somebody know a good website to download labview code to connect a lock-in (Signal Recovery, Model 5210) with GPIB to the computer? I'm still learning to program in labview, Thanks, -Tod

Hello, i'm novice in labview, i've just installed the 5210 lock-in amplifier's driver and i don't know how to use it in my program, can you help me please by giving me an example of a vi using this kind of driver for example? thank you in advance

Read trace 1 (X) in SR850 lock-in amplifier

Hi,
We have a SR850 lock-in amplifier connected to a HP 6632A power supply and both devices connect to a fiber puller.
We are using labview to automate the experiment and right now we are having problems with the labview program giving us the correct trace 1 value when the program runs.
The read trace driver for SR850 is included in our program but the final file, when opened, does not give us the trace 1 from the lock-in amplifier. In other words, the read trace driver is not reading the lock-in amplifier.
Could you please give us any help on this? Please let me know if you need any information from us to help us debug this error.
Thank you very much.
Luciana

Hi Luciana,
Unfortunately, NI's resources are quite limited on this driver since it is not officially supported (according to the SR850 driver download page). Do you have any problems running the examples provided with that driver?
- Greg J

Lock-in amplifier VI to sideband

Hello,
I have a quesiton about modifying the lock-in VI shown here: <link no longer exists> I saw some threads that discussed a similar problem, but there were no clear answers.
We have a infrared signal that is modulated at 280KHz. This signal is interfered with an equal wavelength infrared beam that is modulated at 260 Hz, which then creates a sideband with a better signal to noise compared to just when locked-in to the 280 KHz signal. So, our signal is just one input, but our reference is ONE frequency, but comes from two mixed signals. Here are some pictures of the frequency spectrum showing where we want to lock-in and the setup of the experiment (see attachements). We actually want to lock-in at a sideband of the 3rd harmonic (3*280KHz+260Hz).
I imagine we can input the two references into a daq device, but how should we modify the Lock-in amplifier VI that NI provides ("lock-in amplifier example") to mix the two reference to make the harmonic sideband reference? Can I do this in Labview? We would greatly appreciate any help! The necessary hardware to do this operation cost $30k!!!! Thank you.
-Eric
Attachments:
simplified version of exp.png ‏16 KB
where in spectra to lock-in.png ‏17 KB

Eric,
I'll leave the math to you, but here is an idea, no idea whether it would work. (You can try the math in LabVIEW, without using a DAQ to see if you can get all three frequency components.)
The simplest mixer just multiplies two signals. Assume we have two sinusoidal signals at frequencies f1 and f2, when we multiply them the possible frequencies are f1 + f2 and f1 - f2; the sum and difference components. This is true if we have pure, ideal sine signals.
Now assume we have two square waves at frequencies f1 and f2. If you multiply them together, once again you get sum and difference components f1 + f2 and f1 - f2; however, the square waves contain all of the ODD harmonics, that is, 3f1, 5f1, 7f1, etc and 3f2, 5f2, 7f2, etc. So now you have sum and difference between all these possible combinations, including 3*f1 + f2. (In your earlier post you used the third harmonic, if you need the even harmonics then this will not work.)
Assume we have a function generator with 4 synchronous outputs, see if NI has one. In LabVIEW I can create the signals I want. For one ouput I put a square wave at f1, for another output I put a square wave at f2, for another output I put f1 times f2. That is I am doing all of the math for these signals. I can electronically filter bandpass the mixer ouput for the frequency I want, (hard to have that narrow of a filter) or I can use a math filter in LabVIEW before outputing to analog out for the frequency I want (probably easier). Now you can have phase synchronous signals at three frequencies. (Try the math in LabVIEW.)
Just saw what Lynn said, who is a lot smarter than me. I may be mistaken here, but the time constant on a lock-in amplifier sets the frequency discrimination; for example a 100ms time constant would give you a 10 Hz frequency discrimination. (Here I am referring to a stand-alone instrument, such as the SRS 844.)
Hope this helps.
Regards,
mcduff

Lock-in Amplifier and DAQmx

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