Sigh. You came to the right place, and many of us will tell you that you do not want to use the Dreaded DAQ Assistant (or "DDA"). You especially don't want to use its Evil Twin, the Dynamic Data Wire.
LabVIEW (Laboratory Virtual Instrument Engineering Workbench) is software "invented" by Engineers for Engineers to enable them to "wire" components together to make measurements, move machinery, turn on and off switches, etc.
Here are some tips and general points.
- You are measuring Voltage and Current on a solar cell. So you must haveOp (physical) wires running from your solar cell to something that is connected to the Computer, some "device". Maybe it is a board plugged into your desktop's backplane, maybe it is a little box connected by a USB cable to a USB input on your computer (desktop or laptop). You need to know the "name" of this device.
- LabVIEW comes with a utility called the Measurement and Automation Explorer, or MAX. Open MAX. It has a set of "devices", one of which should (I hope) correspond to the device you are using to measure Voltage and Current. You can use MAX to "play" with your Device, learn its inputs and outputs, configure it to take some data, then actually tell it "Take some data and show it to me as you acquire it".
- MAX allows you to configure your Acquisition device, including getting it to give you data in "scaled units" that make sense to you (i.e. in Amps and Volts, rather than "Signed integers from -32768 to 32767" that you have to scale, yourself.
- You can use MAX to define a "Task" that handles all of the "busywork" for you -- it can define the device you are goihg to use, the inputs and outputs, the scaline, the sampling rate, etc.
- There's a wonderful White Paper from NI, "Learn 10 Functions in NI-DAQmx and Handle 80 Percent of Your Data Acquisition Applications" (do a Web search with the first 5 words of that title). Ignore Point 1 (which talks about the DDA). Pay attention to the rest. It tells you:
- Use MAX to understand your device and create a Task.
- Drop 3-5 DAQmx Functions on your Block Diagram: Start Task, DAQmx Read, Stop Task, with a While loop around the Read (and some other things inside the While to do something with the data you are reading).
Give it a try. Post again, telling us a little more (like naming your Acquisition device, and your attempt at a non-DDA, MAX-influenced 3-5 DAQmx function stab at getting data. Be sure to mention the data rates you plan to use, the range of value you expect, and what you need to do with the data.
Bob Schor
