Faster Read_Waveform of a THS7xx Scope

[Frank Knappe]

Hallo!

I'm having a THS7xx Tekscope and with the supplied Labview drivers
I can control the scope via the serial cable. In my program I only
initialize the scope at the beginning and afterwards I only read the
complete waveform. Unfortunatly this reading takes a long time. Increasing
the baud rate from 9600 to 38400 doesn't help a lot.

I looked at the Read_Waveform.vi and I think it handles a lot of situations
which I don't need. I really only need the waveform of channel one and
nothing else. So I think somebody can simplify this VI.

Has anyone ever does this?
What do I have take care of, if I will try it myself?


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Ciao , Frank .

[Labviewguru]

Frank,

GPIB is your friend. Serial read of that waveform is definitely going to take half of forever. If you get a GPIB cable and card, the read will take only milliseconds.

Also, try changing the baud rate to 115200. This is the rate at which data is transferred. As it is a local instrument, there won't be any problems transferring at that speed. I find it hard to believe that the scope wouldn't be able to handle that kind of speed.

-Mike

[Frank Knappe]

Labviewguru wrote:
> GPIB is your friend. Serial read of that waveform is definitely going
> to take half of forever. If you get a GPIB cable and card, the read
> will take only milliseconds.

I have a GPIB card in my computer and also use it for other things, but
this tekscope (it's a handheld version) only has a serial interface.

> Also, try changing the baud rate to 115200. This is the rate at which
> data is transferred. As it is a local instrument, there won't be any
> problems transferring at that speed. I find it hard to believe that
> the scope wouldn't be able to handle that kind of speed.

The scope only can do 38400. I also made some profiling and changing
the baudrate from 9600 to 38400 hasn't any impact on the real time co
nsuming
subVI's. The real transmitting of the waveform itself isn't the problem.


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Ciao , Frank .

[JRA]

Could you give a little more information about the instrument? I tried looking for the instrument driver on NI's website, but I couldn't find it there. Or, could you just attach the driver and then we can take a look at the VIs? Thanks a lot.

[Labviewguru]

Frank,

I would suggest that you get a new scope. That is the fastest that you can possibly receive the waveform from the scope.

You may want to contact Tektronics to get their suggestions, but I think they will probably tell you the same thing.

Post here the results of your investigations. If there is a faster way to get data, I'm sure we'd all like to know.

[Frank Knappe]

JRA wrote:
> Could you give a little more information about the instrument? I
> tried looking for the instrument driver on NI's website, but I
> couldn't find it there. Or, could you just attach the driver and then
> we can take a look at the VIs? Thanks a lot.

I'm not sure if I'm allowed to attach the driver due to copyright reasons
and the driver isn't very small, so I don't want to attch it here to the
newsgroup.

You can find the driver under:
http://zone.ni.com/idnet97.nsf/9b2b33e1993d877786256436006ec498/
04997f2e03a49519862568ab005fb989?OpenDocument

(this is only one single line URL)

The VI in question is then:
Tk THS7xx Read Waveform.vi

If anyone is interested in my whole program I can send it to him using email.

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Ciao ,
Frank .