Instrument Control (GPIB, Serial, VISA, IVI)

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Question about 4294A programming

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We are currently trying to use Labview to create a virtual front panel for the 4294a, however, we encountered several problems in our trials:

1.       We noticed that the 4294a can work under a continuous (or groups) sweeping mode (internal trigger) which enables the apparatus to measure impedance under a specific frequency for many cycles and we would like to store the data acquired during this time. So what we've done was to first set the parameters for sweeping, trigger the analyzer and stored the data after sweeping. But it seemed that the program ended before the analyzer finished its data sweeping, and the computer only stored a part of the impedance data for one sweeping cycle rather than the whole sweeping data required for all cycles. After reading the program manual we discovered that there happened to be a status register which we can use to detect whether the analyzer has finished one or more sweeps. So we came up with the idea to store data by checking the register status: we process the data storage function whenever a sweep cycle ends, meanwhile the analyzer works under a holding condition only after the data been stored into the computer that we shift the analyzer to the measurement status. So if we choose to process the measurement in this way, we need to know the labview code for checking the register. So can SOMEONE please advise us some ways to do data storage under 'continuous' or 'number of groups' mode or please provide us the right code for status register monitoring using Labview?

2.       We also planned to use the 'List sweep' function and stored data from the multiple sweeps under different frequency range. However, we had no clue on how to set up the table and use the 'Edit List', 'Add' command for our Labview program. Can someone please also help us with the list settings?


Thanks in advanceSmiley Wink

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Would you mind posting some code so I can take a look a deeper look at what you are trying to do?




Hassan Atassi
Senior Group Manager, Digital Support
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Message 2 of 7

Hi Hassan,


we have figure out how to use labview to control the analyzer to get data from multiple frequencies in one sweep cycle. The problem we are now facing is about data storage. What we want to do is to let the analyzer to run under a multiple group mode and store all the data generated in these tests.


Since we discovered that the analyzer would overwrite the data from a previous cycle with the data acquired in a new sweep, so what we want to do right now is to monitor the status register and hold the analyzer whenever it accomplishes a sweep. We plan to store the data right away and then let go of the analyzer to continue its next measurement cycle.


Our problem right now is that we do not know how to check the status register using labview. Can you please help us with that?


I have uploaded our programs. The file named 'List Trigger Qingyuan' is our current main program.


Thank you for your help and patience.



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Message 3 of 7
Accepted by topic author QYT

Right now, you are ignoring the operation complete and the status byte is not being read.  Have you looked at the code or even looked at the VISA palette? The Read STB is right there. Open up the Send Trigger and look at the wait for opc subVI.


And why are you using the older driver instead of the current project-style driver?

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Message 4 of 7

Thank you Dennis, I will look up the sub VI soon. It is because this is our first time use labview, so we really have no idea where to start. What we've done is just to modify the template VI's that we downloaded from the NI website.

Can you please tell me what's the difference between the two drivers, and what convenience or benifit that I can get from the new driver?


Thank you very much.

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Message 5 of 7



There is a good read on the Types of Instrument Drivers.  It includes a section on the project-style drivers. 



Hassan Atassi
Senior Group Manager, Digital Support
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Message 6 of 7

Hi Hassan,


thank you very much for your help and concern, the information you provided to me is really important for our work. However, we have encountered some problems on the visa STB operations. To better address the problem and in order to help other users who might encounter the problem as we do, I have started a new chat on the forum.




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