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Agilent 34980A Data Acquisition

Hello all,

 

I am currently trying to create a VI for data acquisition using a Agilent 34980A unit. I am running LabVIEW 2013 with VISA, NI MAX, and DAQmx. The Agilent is connected through an ethernet cable to my computer and I have sucessfully pinged it from the command screen. 

 

This is my first time creating a DAQ system and I am a bit lost on how to proceeed. I have been using following this page:

http://www.ni.com/white-paper/4646/en/

as a guide. I cannot seem to recreate the VI it illustrates though, as my wires and switches do not correspond to what is shown in the link. Unfortunately the 34980A doesn't seem to have the best support from NI, with no example VIs or extra documentation actually hosted by the NI website. Attached is a screenshot of my file and the file itself.


Can anyone help me fix my VI, give me advice to move forward with, or provide a good resource to learn more about this stuff?

Thanks

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@Option13 wrote:
Unfortunately the 34980A doesn't seem to have the best support from NI, with no example VIs or extra documentation actually hosted by the NI website.

Be happy there is ANY documentation for this.  NI and Agilent are very bitter rivals in the Test & Measurement world.

 

You need to do an Init before any read.  So if you want to constantly gether data, put the init and the fetch inside of the While loop.  There is no need for the Abort either.  And you are also missing the setup for the scan.

 

DAQmx is so much easier...


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So if I were to continuously gather data in a while loop, I would initialize communications for every iteration? I was just copying what Agilent had as an example. Right now I'm just trying to get any data out of this unit. I'm just trying to get one device to work with me. When I finish this project I will need to automatically get data from two 34980A's and several other sensors, roughly every 5 seconds. Would DAQmx still be easier to work with in that case?

 

I'm doing research on it now but an experienced users perspective is always insightful.

 

 

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@Option13 wrote:

So if I were to continuously gather data in a while loop, I would initialize communications for every iteration?


No.  You initiate a scan with each iteration.

 


Option13 wrote:

Not trying to ask too basic of a question, but I have no experience with DAQmx other than having tried to get the Agilent to communicate with it. How similar is it in function to LabVIEW? Or is it more of a subprogram?


DAQmx is NI's driver for their equipment.  Using a PCI(e)/PXI card and controlling them with DAQmx is a lot more intuitive and powerful than the Agilent's 34980A.  If all you are doing is taking measurements, then a simple DAQ card will be MUCH simpler.

 

What sensors are you trying to read?  How many?  What sample rate?

 

I mostly say that DAQmx is so much better because I recently had two projects that dealt with the 34980A and the more troubleshooting I did, the more I found the 34980A to be lacking.


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For some backround, I'm working on a wind tunnel lab for heat exchangers. For air friction alone, not counting any sensors for heat transfer/balance loops, there are at least 36 sensors. Heat transfer loops measure temperature and flow rate for different fluids and have fewer sensors. The whole range of sensors cover temperature, pressure, relative humidity, and flow rate. Most of these sensors are hooked up through the two Agilent units, but there are a few other devices to read the sensors as well. All of them send signals through an ethernet switching board to communicate with a desktop PC through one ethernet cable. Because the lab is running and currently functioning fine and collecting good data through a bespoke DAS, I am not able to switch any hardware and must get all my data through this one ethernet cable. Using LabVIEW would eliminate much of the paperwork currently being filed and save time. As an alternate strategy, is there a way to collect data from this other program using LabVIEW?

 

My inital goal was to make a VI for the air friction portion and modify it to work with the heat transfer portion of whatever fluid was being used at the time. Currently, I'm just trying to communicate with the Agilent and get into this project one step at a time.

 

Sample rate can be low as we only measure once the system has reached equilibrium. A sample rate of 1 Hz for all sensors should be plenty good. It could take an hour for the tunnel to stabilize. We average the signals over a period of 30 seconds.

 

I'm with you on the last bit. Having this be my first attempt at making a DAS is no fun at all.

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If you are completely stuck with the Agilents, then you'll just have to deal with it.  Like I said, you need to initiate the scan and then fetch the data each time you want to read the data.

 

If you are not stuck with the Agilent, I would go with a cDAQ that communicates over Ethernet.  Then it is just a matter of finding the right modules, configuring them in MAX, and then using the tasks in your program.


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