Note that the analog channels in this window are labeled from 1 to 8; the "Analog Inputs" on the DAQ box are labeled from 0 to 7. Make sure you pay attention to this discrepancy in numbering when you are connecting signals to the box.
Note that the analog channels in this window are labeled from 1 and 2; the "Analog Outputs" on the DAQ box are labeled 0 and 1. Make sure you pay attention to this when you are connecting signals to the box.
Simulink Scope Output
Agilent Scope Output (Note differences betweem this graph and previous for t<1 and t>9)
| Command | Output | Explanation |
| >> whos |
Name Size Bytes Class simout 1x1 13594 struct array Grand total 1628 elements, 13594 bytes |
Lists all variables. Simout is a structure. |
| >> simout |
simout = time: [800x1 double] signals: [1x1 struct] blockName: 'rtwShell/To Workspace' |
Ssmout has three parts: time signals blockname |
| >> simout.signals |
ans = values: [800x1 double] dimensions: 1 label: '' |
simout.signals is a
structure with three parts: values dimensions label |
| >> t=simout.time; | time variable | |
| >> y=simout.signals.values; | data | |
|
>>
whos |
Name
Size Bytes Class simout 1x1 13594 struct array t 1000x1 6400 double array y 1000x1 6400 double array Grand total 4032 elements, bytes |
List all variables again. |
|
>>
plot(t,y) >> xlabel('Time'); >> ylabel('Data'); >> title('Real Time Data') >> axis([0 10 -2 2]); >> grid on |
plot (see below) |
Procedure:
Task 0:
- Delete the block labeled "Add Signals" from the Simulink Diagram. We are now going to create our own block that does the same thing.
- Open the Simulink Library browser (go to View->Library Browser from the Simulink menu).
- From the Library Browser add an "Embedded MatLab Function" from the "User-Defined Functions" submenu (under "Simulink") to your Simulink model.
- Double click on the function and rename it MySum.
Add text as shown below.
- Save the block. There should now be a block in your Simulink diagram with two inputs and an output that is labeled "MySum."
- Connect the new block in the place of the "Add Signals" block that you deleted above.
- Compile and run the model to make sure it behaves as you expect it to.
- Save your Simulink model.
Task 1:
- Save your Simulink model under a new name.
- Edit it so it looks like the one shown below.
- Add to the model so that it:
- samples data every 0.01 seconds for 5 seconds,
- outputs a quantity equal to twice the analog input for 0≤t≤4 seconds,
- shows output and input on the scope,
- saves both output and input to simout,
- outputs 0 for t>4 seconds.
- Connect a 2 volt, peak-to-peak, sine wave at 10 Hz from a signal generator to the analog input of the Data Acquisition System and to an oscilloscope. Also connect the output of the D/A to the oscilloscope. Run the program and verify that it works as expected. If it takes more than a few minutes to get everything working, please let me know and I can give you a hand.
- Go to the MatLab workspace and use MatLab to plot both the input and the output.
- Make graphs showing the input and output results when the signal is at 20 and 90 Hz. Make sure you don't change the sampling rate. Also save data in files.
- Save this Simulink model.
Task 2:
- Change your model (and give it a new name) so it generates an output that is the average of the last 5 input points. Do this by using the "Tapped Delay" block (under Simulink and Discrete in Simulink Library Browser). This generates a vector of the last "n" input values. Use an embedded Matlab function to do the averaging (instead of just using Simulink blocks) - you will be using code blocks in later labs, and I want to make sure you understand how to use them.
- Repeat the measurements from Task 1 (i.e., input and output at 10, 20 and 90 Hz).
- Save this Simulink model.
Task3:
- Change your model (and give it a new name) so it generates an output that is the difference of the last 2 input points.
- Repeat the measurements from Task 1 (i.e., input and output at 10, 20 and 90 Hz).
- Save this Simulink model.
Analysis and Report
Strive to be organized, though there is no strict format requirement for this lab. Every graph should be numbered (i.e., graph 1, graph 2...) and labeled (with a title, an x-axis label with units, and a y-axis label with units) and should be explicitly referenced in the report; any tables should likewise be numbered and labeled. You can simply reference these laboratory instructions within your report (rather than merely repeating what I have already written), unless you deviated significantly from these instructions.
Explain (in one or two sentences each) the function of each of the highlighted blocks (labeld A-G) in the diagram below.
Include (at least) the following for Tasks 1 to 3:
- A printout of your Simulink diagram along with any well-documented MatLab code.
- Clearly labeled and documented graphs. Make sure input and output are clearly distinguished. There are several ways to present the data; consider several and pick the one that you feel displays the information most clearly. Make the scale on all graphs the same as much as possible, for easy comparison of results. There are lots of graphs in this experiment, pay attention to organization and presentation (e.g., you can put all graphs from one task on one page...).
- Comment on your results. Explain as much as you can. Be clear and concise.
- If you submit your report as a web page, make it so that all of the pertinent information is on a single page (so I can easily print it out to grade it).