First Project

This is a step by step tutorial on how to first use DAQ Plot. Launching DAQ Plot will show the signals window. Once you acquire voltage signals they will show on the signals window as curves. The rest of this tutorial explains how to get a voltage signal.

Prerequisites

1. Connect compatible DAQ hardware. This tutorial will assume that you are going to use the Basic Hardware. The Basic Hardware is the DLP-IO8-G data acquisition module. To buy that hardware please email sales@vvi.com or consult a retailer such as DIGIKEY www.digikey.com or if you are not in the United States then a retailer local to your area. For other hardware, such as Standard Hardware and Pro Hardware, email sales@vvi.com.

Configure DAQ Plot

2. Launch DAQ Plot. Notice that the signals window comes forwards but otherwise nothing happens. Type command-, (or select the DAQ Plot ► Preferences... menu item) and in the resulting panel make sure the "Hardware" tab is selected and make sure the usbserial-* entry is selected in the Identification pop up button in the lower left of the Preferences window. Then click Apply, it is important to click Apply every time you make a change to the Hardware preferences and also when you first use DAQ Plot. The Preferences shown are the Basic USB Preferences, however if you had other hardware then selecting that hardware in the Identification pop up button would show other hardware preferences. For this tutorial, the preferences are all kept at their default setting so there is nothing more to be done. Close the Preferences window to then make the signals window the only window shown by DAQ Plot.

3. Select the Tools ► Turn Acquisition On menu item. You are now sampling voltage signals from the device. However, you probably did not connect anything to the device so the voltages are uninteresting so the signal curves are equally uninteresting (probably just approximate horizontal lines). If you quit DAQ Plot while acquisition is on then the next time you launch DAQ Plot the acquisition will start automatically.

4. In the Sample Intervals text field enter 0.1 (a tenth of a second) and click the Return key. Now voltages are sampled ten times faster than the default which is one sample per second.

That should be the end of this tutorial because you are now sampling voltage, but no voltage in particular. That is a unsatisfying so lets apply a known voltage in order to produce a varying signal on the signal plot (i.e.: change the curve).

Add A Voltage Source

5. Click off all the switches on the signals window except the first switch, hence only a single voltage will show on the plot, the voltage associated with screw terminal one.

6. Get a small wire, about 5 inches long and of gauge around 16 and strip the last centimeter or so of insulation from both ends.

7. Insert one end of the wire into the "5 V" screw terminal and tighten that screw down on the wire. Then place the other end of the wire into the adjacent screw terminal labelled with the numeral one.

8. Put the wire into terminal one and take it out. Put it in again and take it out. Notice the signal curve goes from (about) zero to five volts whenever you touch the wire to terminal 1. Slight note: Technically the signal "floats" when you remove the wire from terminal 1 since no voltage is being applied to that terminal and hence whatever is available to the terminal at the time is digitized. Many times a floating signal is an arbitrary voltage value but many times it is also near zero volts if the circuit board is designed that way.

Conclusion

This is truly the end of this tutorial. The next step is to connect a sensor or electrical circuit to the DAQ screw terminals. The voltage needs to be from 0V - 5V, but otherwise you are pretty much on you own at this point. See the Rheostat tutorial for a quick idea. You can sample up to eight voltages with the Basic Hardware, remember to turn back on the curves 1-8 on the signals window so that the voltages are displayed. The Basic Hardware is a basic "data logger" piece of hardware. Use other hardware for other features.