This example shows pre- and post-triggering of a signal-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 to trigger on the signal 'Signal Generator' when it reaches 0.0 on a rising slope (signal value goes negative to positive). Pre-triggering is set to 12 samples, meaning that the 12 samples collected prior to the trigger are also stored in the host scope data vector.
Once the trigger condition is met, 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. After every fifth run, the damping gain 'Gain1/Gain' is set to a new random value (between 0 and 2000) and the scope toggles between a 12 sample pre-trigger and post-trigger mode.
Rationale for choosing 12 samples: The model sample rate is 250 usec. Since the decimation factor for the scope is set to 4, the difference between two acquired samples is 1 ms. The 'Signal Generator' block outputs a square wave at 20 Hertz (50 msec per wave). Therefore, the acquisition will be shifted by 12 ms (approximately 1/4 of a square wave) each time the scope is updated.
Use 'slrtpingtarget' to test the connection between the development and target computers.
if ~strcmp(slrtpingtarget, 'success') error(message('xPCTarget:examples:Connection')); end
Open the oscillator model, xpcosc. Under the model's configuration parameter Simulink Real-Time options settings, the system target file has been set to slrt.tlc. Hence, building the model will create an executable image, xpcosc.dlm, that can be run on a computer booted with the Simulink Real-Time kernel.
Build the model and download the image, xpcosc.dlm, to the target computer.
set_param('xpcosc','RTWVerbose','off'); % Configure for a non-Verbose build. rtwbuild('xpcosc'); % Build and download application.
### 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 ### Looking for target: TargetPC1 ### Download model onto target: TargetPC1
Create the MATLAB® variable, tg, containing the Simulink Real-Time target object. This object contains the information required to communicate with and control the target computer.
tg = SimulinkRealTime.target; % Create a Simulink Real-Time target object tg.SampleTime = 0.000250; % Set sample time to 250us tg.StopTime = 10000; % Set stop time to a high value (10000s) start(tg); % Start model execution
Create, configure, and plot to the host scope during each run.
tPar = getparamid(tg, 'Gain1', 'Gain'); % Get index of parameter 'Gain1/Gain' signals(1) = getsignalid(tg, 'Integrator1'); % Get index of signal 'Integrator1' signals(2) = getsignalid(tg, 'Signal Generator'); % Get index of signal 'Signal Generator' sc = addscope(tg, 'host'); % Define (add) a host scope object addsignal(sc, signals); % Add signals to signal list of scope object sc.NumSamples = 200; % Set number of samples sc.Decimation = 4; % Set decimation factor sc.TriggerMode = 'Signal'; % Set trigger mode sc.TriggerSignal = signals(2); % Set trigger signal to 'Signal Generator' sc.TriggerLevel = 0.0; % Set trigger level sc.TriggerSlope = 'rising'; % Set trigger slope sc.NumPrePostSamples = -12; % Set pre-triggering to 12 samples figh = findobj('Name', 'scprepostdemo');% Does the plot figure exist? if isempty(figh) figh = figure; % No: Create figure set(figh, 'Name', 'scprepostdemo', 'NumberTitle', 'off'); else figure(figh); % Yes: Make it the current figure end % Loop to acquire 25 data packages from the scope object. m = 1; flag = 0; for n = 1 : 25 if isempty(find(get(0, 'Children') == figh, 1)), flag = 1; break; end if ~m % Change parameter Gain1/Gain every fifth acquisition loop % to a random value between 0 and 2000. setparam(tg, tPar, 2*1000*rand); % Toggle between pre- and post-triggering sc.NumPrePostSamples = -sc.NumPrePostSamples; end m = rem(m + 1, 5); start(sc); % Start scope object % Wait until scope object has 'finished' state. while ~strcmpi(sc.Status,'finished'), end; % Create time vector, upload scope data and display it. t = sc.Time; % Upload time vector plot(t, sc.Data); % Upload acquired data and plot if (sc.NumPrePostSamples < 0) textString = '(Pre-Triggered)'; else textString = '(Post-Triggered)'; end title(['scprepostdemo: ', num2str(n), ' of 25 data packages ' textString]); set(gca,'XLim',[t(1), t(end)], 'YLim', [-10, 10]); drawnow; end if ~flag, title('scprepostdemo: finished'); end
When done, stop the application and close the model.
stop(tg); % Stop model close_system('xpcosc',0); % Close model