Continuously reading (recording) data from Agilent 6674A power supply through GPIB-USB interface

[bhk]

Hi there,

I would like to record the current output in larger than 200 HZ from my Agilent 6674A DC power supply through LabVIEW 8.2. Agilent 82357A GPIB-USB interface is used to connect the power supply to computer. And I used the instrument driver for Agilent 66XX I downloaded from NI.

To read the data continuously, I put the read.vi in a while loop and recorded the data by writing to lvm file. (just for starter, not a good way though) Please see the attached file.

The problem I have is that I only can  record data in~ 10 HZ while what I need is at least 200 HZ. 

This is my first time for instrument control and I just had a little experience in DAQ before. I had some confusions as below: Did I acquire just one point each time the while loop is executed? If yes, I guess then the time for each loop (and hence my data rate) depends on my operating system and computer I have.

How many points are gonna be acquired each time the read.vi is execute? Does that depends on the "byte count" set in the vi or just one point no matter what? Is there any other ways to acquire data more effectively? (like to write your own driver etc...) Any help would be very much appreciated.

Cheers,

Bohan 

[Dennis_Knutson · Accepted solution]

The rate at which you can run the VI is dependent on the instrument/GPIB bus and the use of the Write to Measurment File. Yes, you are acquiring one voltage reading and one current reading with each iteration and the number of bytes read is so that you can get one complete reading.

I would suggest that you remove the Write to Measurement File from the loop to see how long the instrument alone takes. This would be your maximum rate. If that is fast enough, use a different method to save the data. A producer/consumer architecture where you pass the data to a separate loop via a queue would be one way.

[bhk]

 

thank you so much for the prompt response and answers to my confusion!!

I'll try that out and see what works best for me.

Cheers,

Bohan 

[devoldev]

Hi Bohan,

I tried to apply your program using the same couple of 6674a and 82357 interface but using 8.6 (under vmware emulation on a macbook) and had trouble in the connection: the program does not see the interface and had problems in locating some files; using the original driver by agilent the interface is fully visible; you have used a visa driver; is it correct? may you comment this? have you ideas about? thank you

[bhk]

Hi,

You may wanna look at this, http://digital.ni.com/public.nsf/websearch/3B3626D9C1F999218625694200791AD7?OpenDocument

Let me know how it works.

Cheers,

Bohan