MATLAB Examples

Signal Tracing Using Software Triggering

This example shows how to trace a signal using a software triggered Simulink® Real-Time™ host scope. After the script builds and downloads the oscillator model, xpcosc, to the target computer, it adds a scope of type 'host' to the real-time application and the signals 'Integrator1' and 'Signal Generator' to the scope. The scope is then configured in the software trigger mode.

Once the trigger is initiated, the scope is monitored to determine when its data acquisition is complete. Next, the scope data is uploaded to the development computer and plotted. This process repeats 25 times. The software trigger is re-enabled each run after a random pause (between 0 and 4 seconds). After every fifth run, the damping gain 'Gain1/Gain' is set to a new random value (between 0 and 2000).

Contents

Check Connection Between Development and Target Computers

Use 'slrtpingtarget' to test the connection between the development and target computers.

if ~strcmp(slrtpingtarget, 'success')
  error(message('xPCTarget:examples:Connection'));
end

Open, Build, and Download Model to the Target Computer

Open the oscillator model, xpcosc. Under the model's configuration parameter Simulink Real-Time option settings, the system target file has been set to slrt.tlc. Hence, building the model will create an executable image, xpcosc.mldatx, that can be run on a target computer booted with the Simulink Real-Time kernel.

open_system(fullfile(matlabroot,'toolbox','rtw','targets','xpc','xpcdemos','xpcosc'));

Build the model and download the image, xpcosc.mldatx, to the target computer.

  • Configure for a non-Verbose build.
  • Build and download application.
set_param('xpcosc','RTWVerbose','off');
rtwbuild('xpcosc');
### Starting Simulink Real-Time build procedure for model: xpcosc
### Generated code for 'xpcosc' is up to date because no structural, parameter or code replacement library changes were found.
### Successful completion of build procedure for model: xpcosc
### Created MLDATX ..\xpcosc.mldatx
### Looking for target: TargetPC1
### Download model onto target: TargetPC1

Run Model, Randomize 'Gain' Parameter, Plot Host Scope Data

This code accomplishes a number of tasks.

Task 1: Create Target Object

Create the MATLAB® variable, tg, containing the Simulink Real-Time target object. This object allows you to communicate with and control the target computer.

  • Create a Simulink Real-Time target object
  • Set sample time to 250us
  • Set stop time to a high value (10000s)
  • Start model execution

Task 2: Create, configure, and plot to the host scope during each run.

  • Get index of parameter 'Gain1/Gain'
  • Get index of signal 'Integrator1'
  • Get index of signal 'Signal Generator'
  • Define (add) a host scope object
  • Add signals to signal list of scope object
  • Set number of samples
  • Set decimation factor
  • Set trigger mode

Task 3: Check for Plot Figure

Does the plot figure exist?

  • If no, create figure
  • If yes, make it the current figure

Task 4: Loop to acquire 25 data packages from the scope object.

Change parameter Gain1/Gain every fifth acquisition loop to a random value between 0 and 2000.

Task 5: Start scope object and trigger randomly

  • Start scope object
  • Wait until scope object has 'ready' state.
  • Randomize the amount of wait time before triggering scope.
  • Wait a random period (0..4s).
  • Software trigger the scope object.
  • Wait until scope-object has 'finished' state.

Task 6: Create time vector, upload scope data and display it.

  • Upload time vector
  • Upload acquired data and plot
tg = slrt; % create target object
tg.SampleTime = 0.000250;
tg.StopTime   = 10000;
start(tg);
tPar = getparamid(tg, 'Gain1', 'Gain'); % get indexes
signals(1) = getsignalid(tg, 'Integrator1');
signals(2) = getsignalid(tg, 'Signal Generator');
sc = addscope(tg, 'host'); % define scope object
addsignal(sc, signals);
sc.NumSamples  = 200;
sc.Decimation  = 4;
sc.TriggerMode ='Software';
figh = findobj('Name', 'scsoftwaredemo'); % check for plot figure
if isempty(figh)
  figh = figure;
  set(figh, 'Name', 'scsoftwaredemo', 'NumberTitle', 'off');
else
  figure(figh);
end
m = 1; flag = 0; % loop to acquire data
for n = 1 : 25
  if isempty(find(get(0, 'Children') == figh, 1)), flag = 1; break; end
  if ~m
    setparam(tg, tPar, 2*1000*rand);
  end
  m = rem(m + 1, 5);
  start(sc); % start scope object
  while ~strcmp(sc.Status, 'Ready for being Triggered'), end
  ttrigger = rand * 4; % randomized trigger time
  title(['scsoftwaredemo: ', num2str(n), ...
         ' of 25 data packages, will be triggered in ', ...
         num2str(ttrigger), 's']);
  pause(ttrigger);
  if isempty(find(get(0, 'Children') == figh, 1)), flag = 1; break; end
  trigger(sc); % software trigger scope
  while ~strcmpi(sc.Status,'finished')
  end
  t = sc.Time; % create time vector and display it
  plot(t, sc.Data);
  set(gca, 'XLim', [t(1), t(end)], 'YLim', [-10, 10]);
  drawnow;
end
if ~flag, title('scsoftwaredemo: finished'); end

Stop and Close Model

When done, stop the application and close the model.

  • Stop model
  • Close model
stop(tg);
close_system('xpcosc',0);