can't acquire 2 channels

[carolyne]

Hi,

I'm using a Tektronix TDS 1002 with Labview 8. I want to recover 2 channel datas on the same Labview screen.

I tried with the Tektronix TDS 200 1000 2000 Series Acquire Multiple Waveforms.vi example and adding possibilities to do more settings for the 2 different channel but I have only one channel which works.

The vertical range is very different for the 2 channel (one at 5V/div and the other 5mV/div). So is there any function to realize that ?

I've looked at http://digital.ni.com/public.nsf/allkb/9fc2291d4cf6851a862567b30050ab12 about "How Do I Use a Scope Specific Instrument Driver to Acquire Multiple Waveforms Simultaneously?" and they talk about replacing read.vi by fetch.vi...

Can you tell me more about this maybe there is a link with my problem.

Thanks

[Stuart_R]

You need to use Read (Multiple Waveforms).vi and failing that maybe start looking at the Fetch functions.

Have you read through the instruments user manual to see if there are any caveats?

I don't have one of these instruments so can't try this out, but surely it shouldn't be too difficult.

What exactly happened when you tried to use the methods described?

[carolyne]

In fact, I've replaced the read function by initiate and fetch functions but an error appears and says there is problem with configure channel.vi.

Settings seem correct so I don't know...

[carolyne]

The exact message is:

Error -1073807360 occurred at VISA Write in Tektronix TDS 200 1000 2000 Series.lvlib:Configure Channel.vi->hold-up time2.vi

But it's very strange because if I go through this error the second channel is displayed (but not the first one).

[Stuart_R]

Not sure what the problem there is then. Without the instrument itself, I can't really try anything out myself. Maybe someone will post who actively uses thsi instrument.

Can you acquire from each channel individually?

[carolyne]

No I can't acquire from the second one...

[Russ_Evans]

Hi Carolyne,

I am pretty sure Tektronix provides software for acquiring data on their scopes. I think it might be PC only and it's called something like "Open Choice" . Anyway have you tried using it and was it successful at acquiring all channels.

Cheers,

--Russ

[carolyne]

Dear Russ,

I don't understand exactly what you want to say about "open choice" and Tektronix software.

Can you explain me a little bit more please ?

Thanks

[Russ_Evans]

Hi carolyne,

I have used Tek's OpenChoice desktop application to acquire from some 4 channel TDS 2000 series scopes. Check out the following

http://www.tek.com/Measurement/scopes/connectivity/

Now the software has limited functionality but it does acquire the waveforms that are displayed on the scope and displays them on your computer then you can save the traces to hard disk. The software either came with the scopes or with the communication modules that were purchased concurrently. Either way I believe the desktop application is a free download.  So if you still have your documentation with your scopes look for a CD -ROM it's probably included on it.

One caveat is that I remember it didn't want to play well with the VISA dll's installed by NI. It didn't seem to be a fatal flaw but I do recall error messages. Here is a quote from the installation notes of TekVISA (required by Open Choice)

"It is recommended to uninstall any previously installed version of VISA on 
the PC or Windows-based oscilloscope. This includes versions of TekVISA 
installed by WaveStar or VocalLink, and versions of VISA from National "
Instruments, Agilent, and other vendors.

[carolyne]

Dear Russ,

Indeed, we received some software with the oscilloscope. The issue is that we want to realize a work bench entirely made with Labview because tests on products will be done without our surveillance. So we can't take the liberty of using others software because it means that they will be controlled by Labview and it seems really too complex.

We saw with my colleague that the Base Package doesn't allow we to manipulate waveforms to save them in other files and in other sizes. So, I think for the moment I will content myself with the write measurement file function even if the amount of datas will be enormous. And I will try to manage with the 1-channel acquisition as well but if you have some ideas about this particular point I will be happy to receive them.

Thanks for you help