How to fasten ethernet data reading ?

[flanguy]

Dear all,

thanks to this tutotial (http://digital.ni.com/public.nsf/allkb/92D475E7246846E786256ED700556D98) I am able to read data from a Keithley 2701 connected through Ethernet.

My VI is very simple but it takes around 0,25 s to ead a data and I need to read at 10 Hz.

I think that the main problem comes from the need to always send a Write comment and then get the data. Is it possible to send only once a command and then get data in a continouous way ?

Find attached my VI.

Thank in advance for your help

[moderator1983]

Though I'm not sure, is there any option available for this hardware, so that you can configure it for continous datalogging and store the samples on the memory available on the device itself and then your program can fetch those samples on periodic basis.

Usually reading over ethernet is very fast.

I found this document here which describes how you can configure it to acquire samples faster.

Edited: Also I would like to mention, you can very easily avoid using local variables in your program, attached is the modified code.

[moderator1983]

Though I'm not sure, is there any option available for this hardware, so that you can configure it for continous datalogging and store the samples on the memory available on the device itself and then your program can fetch those samples on periodic basis.

Usually reading over ethernet is very fast.

I found this document here which describes how you can configure it to acquire samples faster.

Edited: Also I would like to mention, you can very easily avoid using local variables in your program, attached is the modified code.

[GerdW]

Hi flanguy,

it's not just speed of your device connection, it's also (and probably mainly) the time the device needs to response to your request!

What does the manual of your DMM say about sample rates? What does it say about response times?

I remember such DMMs do read new values with just 1S/s for best resolution. So it may even take a full second to deliver a new measurment value on your request…

I also remember those Keithley DMMs offer some kind of "block read mode" using their internal buffer to store values. THat way you may be able to sample data at 10 Hz samplerate and fetch all values later on.

It's all in the manual, so read it… (Do you know the acronym "RTFM"?)

[moderator1983]

Here is the link.

[moderator1983]

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@GerdW wrote:

Do you know the acronym "RTFM"?

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ha ha ha.

[crossrulz]

You might want to have a look at the drivers that are available for that DMM:http://sine.ni.com/apps/utf8/niid_web_display.download_page?p_id_guid=0470C9F181C02E75E0440003BA7CCD...

I haven't looked closely at them yet, but there should be some VIs in there to do a scan of X samples at whatever rate you want and then gather them up.