Increase the sampling rate of keithley 2000 DMM

[yogesh10994]

I am making a labview programme which requires data (AC Current) at 1024 Samples/sec. The Keithley 2000 DMM can supply at 1024S/sec. 

In the manual, I read that to do so, I need to create a data buffer in the DMM, configure the trigger, send the trigger, initialize the trigger, wait for the data acquisition and then read the buffer.

Problem:

1). The VI is giving a timeout error

2). While creating the data buffer, keithley 2000 gives error -140......I guess because of this error....I am getting a timeout error in the VI.

3). Also when trying to read the buffer, I don't know how much byte to read.......I only know that I am reading 1024 data points....Therefore I am using the max 32768 bytes....but still getting the timeout error....

I have attached my VI, manual and the screenshots of the commands from the manual that i have used.....

Edit: I have attahed the VI of 2013 version also...

Thanks in Advance!!!

[Henrik_Volkers]

Spec of the DMM in ACI mode is 35/s to 300/s(?) .....

If you read current in DCI with 5.5 digits you can get 1k/s   (2k/s at 4.5digit) 

What signal(s) do you want to measure?

[yogesh10994]

I need to measure the AC current.....

[Henrik_Volkers]

Bandwidth ?

Sine , pulse, crest factor, noise?

What information do you need to know ? ACI can be a 50Hz line current... but you have a 20ms periode ,so no way to read ACI with more than 50/s.... 😉  If you want to look at higher frequency content at the same time the usualy way is to measure 'DC' fast enough to reconstruct the signal.

[yogesh10994]

Let me explain you my experiment......

We have made a piezoelectric device.... we will impact it with a sinusoidal force (frequency ranging from 5 Hz to 20 Hz, hence the output voltage signal is also between 5 to 20 Hz).....As a stress is developed in the device, it generates voltage......We are interested in measuring the voltage......

Although because of the line frequency (50 Hz), there will be noise in the voltage signal....but we can reduce the noise.....this comes later....

Right now, I want to measure data at higher sampling rate.....whether there is a need 1024,300,100 or 50 S/sec, it is upto the user...it can be changed via program....First, I need to know what changes is to be made in my VI that I have attached so that I can measure data at user defined Sampling rate...

PS:  Also as mentioned in the manual...I can store 1024 data points in the buffer....therefore max sampling rate becomes 1024 S/sec.....I have attached the screenshot...... 

[Henrik_Volkers]

AC (I or V) measurements are slow because of the measurement principle. Without looking it up, I bet it's explained in the manual 😉

What you should use is DC sampling at 2000SPS(sample per second).

Just because the buffer can only hold 1024 samples, you are not restricted to 1024SPS

You can sample 1024 values at 2000 SPS .. about half a second of data 😉