What am I trying to do is to save in a variable (global or constant) the system time. I am using a S-function in Simulink. The problem is that when I store the value of the system time in a variable it is continuously incrementing so when I do the difference between the current system time and the time stored in my variable is always 0. What do you think is the solution storing the system time in a variable and what type of variable should I use a global one or a constant. If you have any answer please give me an example because I am new in Matlab.
P.S I am using C language for the S-function.
It sounds as if you are trying to store the system time at the start of the simulation, then during the simulation compare the system time to that stored value. If so, then you should be using anR-Work vector to store the initial system time.
So in mdlInitializeSizes you want
ssSetNumRWork(S, 1);
Then in mdlStart you want
real_T *P_Tinit=ssGetRWork(S);
P_Tinit[0]=((real_T) clock())/CLOCKS_PER_SEC;
Then when you want to use the value use,
real_T itime;
itime=ssGetRWorkValue(S,0);
(The above assumes that you know how to actually get the system time, i.e. include the correct libraries, which from your question it sounds as if you do.)
Related
I have a simulink model that generates signals, I want to store the signal using data store write and data store memory (those are linked together), then I want to be able to use the stored signal (an array) as a global variable in MATLAB.
When I try to make the variable global in matlab nothing happens. Even after I start the simulation
global Signal_full_og; %the variable I want to make global
sig_arr = [];
sim simF.slx %simulation file
for vref= 0:1:10 %1st 10 signals
sig_arr(index, :) = Signal_full_og;
end
Below there is a picture of the Data Store Write and Data Store Memory from my Simulink model
And below there is a picture of the block parameters of Data Store Memory
I have tried to follow the documentation from Mathworks and still I can't get a global variable. Does anyone spot any mistakes in this way or is there a better way to do the same thing?
I created a model of a system of ODE's. The system contains 3 functions, say x,y,z I'd like to investigate.
The problem is that the time variable in the system is not
t (time)
but
omega*t
where omega has a fixed value. My question is how can I take the new time variable into considerations in my system? thanks.
I am trying to make a simulation in Simulink, with the fuzzy model.
As inputs, I have set four time series variables from the workspace (compatible to simulink after performing Simulink.Timeseries function): every row of the variables has a linked time starting from 0 to 10566 (seconds, I believe). How can I set the sample time in simulink source block in order to pick every exact case without interpolation?
Thank you for your kind answers,
Phalaen
Are you using the From Workspace block? If so, it's simply a matter of specifying the sample time in the block parameters and unticking "Interpolate data". You can also display the sample time information of the model to check which sample time each block is using, see View Sample Time Information in the documentation.
I'm using the simulink block From Workspace to read in some audio data provided by a script. I have formatted the data in a matrix with 2 columns, the first is the timestamp and the second is the data.
In the configuration paramaters, I have specified Fixed-Step and Discrete solver. The Start time and Stop also need to be configured manually and don't seem to come from the data.
Also, in the From Workspace block configuration, I need to specify the sample time (1/44100) or I get a warning if I specify -1, to inherit from the data and then get strange sample times.
So, how can I get simulink to use only the sample times in the matrix and use the first and last timestamps as the start and stop time of the simulation?
You should be able to do what you want by doing the following:
Firstly note that your problem is by definition not fixed step, hence you cannot use a fixed-step solver, which by definition is ... fixed-step.
You must use a variable step solver.
Assuming your (2 column) input data is called simin then set the start and stop times to be simin(1,1) and simin(end,1) respectively.
In your From Workspace block set the sample time to be 0 (which should have been the default).
Also de-select the Interpolate data option; and set "Form the output after final data value by:" to zero (you won't be using anything past the end of your data set so this should be OK.
Then you need to tell the solver to take additional steps to those that it would naturally want to take.
Do this on the Data Import/Export pane of the Model Configuration Parameters.
Near the bottom of the pane there is a selection box and an edit box for doing this.
Note however that this does not prevent the solver from taking steps at other time points, it just forces it to take additional steps at the times you specify.
But because you have your From WOrkspace block to not interpolate this shouldn't be a problem either. You should put simin(:,1) in here so that the solver is guaranteed to take steps at the time points in your input data.
Note that if you want an input block that only samples at the time points in the simin time vector then the only way to do this is to write an S-function that uses the mdlGetTimeOfNextVarHit method to tell the solver what the next sample time (for this block) should be.
I am working on a simulink model, in which i am getting a supply of a a variable at certain time intervals and i need to use the recent 10 values of that variable only.
how should i proceed with that?
It's a bit cheesy, but how about using a chain of Unit Delay blocks?