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Fast Continous Remote Measurement With 6517B

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mickw89
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Fast Continous Remote Measurement With 6517B

Post by mickw89 » November 30th, 2020, 1:02 pm

We have a Keithley 6517B electrometer in our lab and I'd like to use to perform a fast (>100 samples per second) continuous measurement. I've been able to communicate with it using python (PyMeasure) and a GPIB-USB converter. I can configure the buffer size, have it perform measurements, filling up the buffer and I can poll the MSB bit so see when the buffer is full and read the buffer. What I'd like to know is how should I go about making this into a continous measurement without sacrificing most of the speed. I can do continous single measurements by read/writing :MEAS? but this is too slow and results in about 1-2 samples/second. I know the Keithley can be fast, with 0.01 nplc and and lsync off I get down to about 2.3 ms per sampls (still more than the 0.01 nplc but fast enough for my application). I'd like the Keithley to keep filling the buffer while I read chunks of the buffer, but I don't know how to do that.

P.S. A side issue I have is that we operate with a 50 Hz mains but for some reason the 0.01 nplc results in a 1.6667E-4 aperture instead of 2E-4 and I don't understand why that happens.

Andrea C
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Re: Fast Continous Remote Measurement With 6517B

Post by Andrea C » December 17th, 2020, 4:53 am

From datasheet, the reading rates across the bus will be ~400Hz, so your achieved rate of 2.3msec per reading is already at the limit for what it can do.
There is a 2V analog output signal. You could monitor that with a DMM or Scope.
Range changes affect the 2V scale factor so that is a consideration.

HakimJacob
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Re: Fast Continous Remote Measurement With 6517B

Post by HakimJacob » January 4th, 2021, 8:52 am

Hi...I approach in the lab to a Keithley 6517B electrometer, and labview 2009, and I need to make an interface with labview to quantify current I, voltage V or opposition, simultaneously I need utilize the 6517B electrometer as a wellspring of voltage or current to assess qualities before referenced, I have the fundamental equipment ( Keithley GPIB KUSB-488A).

I see the models remembered for the driver and in the site of keithley, yet non incorporate the yield of voltage/ebb and flow model. I don't have a lot of involvement, however I am ready to actualize what is important to gauge, yet not for design it as voltage/current source.

The thought is to have the option to quantify: as model, volume resistivity or the current in presence of a voltage (6517 as a source) and view a diagram and save the information produced.

gwryus
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Re: Fast Continous Remote Measurement With 6517B

Post by gwryus » September 21st, 2021, 9:59 am

@Andrea C -- I have a similar need to @mickw89...but at a slower speed. How would I set up the 6517B to keep filling up the buffer while I would read chucks out of the buffer?

Is there a way to set the 6517B up to stream data without a having to request each data point or a specific number of data points in the buffer?

Andrea C
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Re: Fast Continous Remote Measurement With 6517B

Post by Andrea C » September 26th, 2021, 9:03 am

For a continuous measurement where the number of samples desired exceeds the buffer size, the only way is to loop on the PC side and send read command and then read the response into the PC. Data sheet indicates this will not be faster than 400readings per second and requires various settings for speedy operation.

Consider a fixed measure range and using a volt meter to stream the I to V analog output value that the 6517B provides. It’s a transimpedance amplifier that generates -2V mapped to the full scale value of measure range.

Depending on how fast you are wanting and the signal level you are trying to measure, a SMU or dmm may support your streaming desire.

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