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

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connection error.jpg ‏84 KB

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31x34 2007                8x47                 4110.8599999999692953          speakers
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31x34       8x47           8743.079704290217582865      pickles
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16x67 2007                8x41                 3840.1447436467236765            southwestern burger
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31x34                        8x47                 3940.7899999999823942          chipotle meal
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32x76                       8x10              117756.91                           juice
                                                      52116.229999999969462937         fish n chip
32x59                                               64675.1499999994542136           paper
                                                      64959.1799999998650161           markerss
33x58                       8x37                44334.3858770048316717           paint
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Hi,
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Attachments:
SETDAC.c ‏2 KB
setdacwin.h ‏2 KB
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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.
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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.)
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Regards,
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