I've read that I can generate code from Simulink models/block diagrams. I am curious whether Simulink always converts a model to (c/c++/java) code prior to running a simulation in the Simulink software, and then execute that code? I mean, whenever I'm running a simulation is Matlab converting the block diagram to (c/c++/java) code and running that code behind the scene. In this case, simulation in Simulink directly depends on running some code; this information is important to me in some way.
Generating and running code for a complete model seems plausible, as we can write s-functions using C/Matlab code and use them as custom blocks. So simulating a model involves running code in some degree. Again, since we can write Matlab code as well, simulation may involve interpreting Matlab code in some environment. It makes me curious whether these information are available - how tightly running a simulation in Simulink depends on executing native code in user's machine.
I did some search before posting and found this SO question: How does simulation engine work? Discussion in this question does not answer my question directly.
The answer depens on which mode you chose.
In the normal mode Simulink will run the model as it is primarily using the MATLAB execution engine. No code is generated. Native implemented parts (e.g. S-Functions) are used as individual binaries called by the MATLAB interpreter.
In the accelerator mode Simulink generates model code. This means your full model (except parts where code generation is impossible) is generated and compiled into one binary.
In the rapid accelerator mode not only your model but also the solver is generated and compiled into one binary, now running in a separate process.
For more details refer to the official documentation
Related
I would like to use the Application Compiler (Appdesigner -->Standalone Desktop App) on my MATLAB app. This app calls a .m file which is using the rtwbuild command to deploy a Simulink model to an arduino. The app works well when run in MATLAB, however after compilation I receive an error with rtwbuild:
Error using rtwbuild
The Matlab Path must have these directories for Simulink to function:
toolbox/simulink/blocks, toolbox/simulink/simulink
Matlab cannot continue. Please restore the path and restart Matlab
The documentation says, that no Simulink functions are supported for the MATLAB Compiler (see here) and the rtwbuild function seems to be a Simulink function, since it is in the documentation in the category "Simulink Coder" (see here). However, I do not have the Simulink Coder Toolbox and the app was running in MATLAB anyway, so I am not sure if rtwbuild is really a Simulink function.
To keep it short, my question is the following:
"Is it possible to use the Application Compiler on .m scripts including the rtwbuild command?"
Thank you for your help!
rtwbuild is without a doubt a Simulink Function, which means the MATLAB-Coder can not generate code. More generally speaking, you can not deploy the code generator. Generating code from M or Simulink requires a full MATLAB (Simulink) to be running. It would be foolish to let you use such a key feature without a MATLAB (Simulink) license (personal opinion).
About your confusion about rtwbild being part of the Simulink Coder. The Support Package for Arduino Hardware allows you to use certain deployment features. You can for example get binaries, you can not access the C code without having a Coder License. For details refer to "Additional Capabilities with Simulink Coder and Embedded Coder" in the documentation.
The documentation does not reflect these special cases, but obviously TMW did not re-invent the wheel when providing the Support-Packages for Arduino. Instead some "Simulink Coder" functions do not require a Simulink Coder License when used with the code generation Target Arduino. Same is true for the Raspberry and to a limited extend for the (rapid) accelerator mode.
Is there an alternative function to the sim() command oder a direct way executing a Simulink Model / a compiled version of it from Matlab without setting coder.extrinsic?
I want to execute a simulink model inside of an iterative Matlab-function. (Hence, speed matters dramatically). The used Simulink model contains a Dymola interface and hence, I cannot model it directly in Matlab. Another main Simulink model starts and iterates the Matlab functions and hence, simulating it leads the coder trying to compile it efficiently. By setting coder.extrinsic, of course I can use the sim command, but it is way too slow for its purpose. I thought about compiling the Simulink model as an alternative, but do not know if this would be a good approach
The structure looks as follows:
Simulink main model -> matlab functions -> simulink model
sim command needs MATLAB. So you need coder.extrinsic. There is no direct alternate way without coder.extrinsic to simulate a model. You can generate code from the model and call the generate code using coder.ceval functions. But if your goal is only to get more speed instead of getting stand-alone code you can set your model to run in accelerator mode and see whether that improves speed.
I want to make a biometric identification system of the ECG/EKG.
Provided that Matlab does not perform Data Acquisition in Real Time (for monitoring), is there any way to make the monitoring and data acquisition in LabVIEW and then work simultaneously with Matlab for signal processing?
You could just get a matlab compatible daq and run everything in matlab. http://www.mathworks.com/products/daq/
You can indeed do some data acquisition with LabView and work simultaneously with Matlab for signal processing by calling the Matlab script node, which executes some Matlab code during vi execution.
You may have some performance issues, though, because both Labview and Matlab have to run on your machine simultaneously.
Question:
is there any way to make the monitoring and data acquisition on
LabView and then work simultaneously with Matlab for signal processing
Answers:
LabVIEW has "MathScript" node which is basic MatLab built into
an add-on. It is not the MatLab toolboxes. It runs native MatLab
code. It also runs slightly faster LabVIEW updates to the code. If
your code runs there, then LabVIEW will pass data natively
to your code. This box does not have direct MatLab toolbox access, so if
you use any special calls then that can cause a problem.
If you have MatLab on the box, then you can call the external MatLab
function/code using mathscript (link), and the MatLab will run
the function.
Clarification:
Real time just means "bounded time" (link), not "instant". If your idea of bounds are loose enough then many systems can work for them. You do not state it in your question - but what do you consider acceptable response time?
I've worked a lot with LabVIEW and Matlab. Personally, I would not use the Math Scripting node and would opt for using the Matlab Automation Server. You can call Matlab from LabVIEW using the ActiveX palette in LabVIEW (See Functions>>Connectivity>>ActiveX>>Automation Open) A couple reasons why I'd go for ActiveX and NOT the MathScript node:
The Math Script node does not allow you to change code dynamically. You must hardcode your data into the Math Script node and any future changes would require a change to LabVIEW's G code and therefore a recompile of your EXE
The Math Script node does not support all functions when compiled to an executable. Most notably graphing functions. See the help file here to read more on this.
Calling Matlab from ActiveX is going to give you a lot more flexibility in regards to how data is passed and processed.
I wonder if there's some experience out there, how much performance can be gained from using the Simulink Coder to generate models over running the model in (rapid) accelerator mode?
For instance, how does it compare to the quite dramatic improvements from not-accelerated to accelerated models?
I know this is kind of vague and probably depends on the specifics of a model, but I'd be happy with examplary numbers.
I don't know if you will really find speed improvement anecdotes that helpful, as your results are going to be highly dependent on your own implementation.
That said, the following reference on How Acceleration Modes Work might be useful to you.
As described in this link...
The Accelerator mode generates and links code into a
C-MEX S-function. Simulink uses this acceleration target code to
perform the simulation...
...the model methods are separate from the Simulink
software and are part of the Acceleration target code. A C-MEX
S-function API communicates with the Simulink software, and a MEX API
communicates with MATLAB. The target code executes in the same process
as MATLAB and Simulink.
The link goes on to describe Rapid Acceleration, as such:
The Rapid Accelerator mode creates a Rapid Accelerator standalone
executable from your model. This executable includes the solver and
model methods, but it resides outside of MATLAB and Simulink. It uses
External mode (see Host/Target Communication) to communicate with
Simulink.
(Note that the actual link has some nice diagrams that help to illustrate this architecture).
I think that there are a few important things to takeaway from these descriptions. First, in Accelerator Mode, code is only generated for the model methods; however, in Rapid Accelerator Mode, code is also generated for the solver. In either case there will be some overhead due to communication between the generated code and Simulink (though in general that overhead would be greater in non-rapid accelerator mode).
Now, whether you are going to see significant differences between these acceleration modes and full-on code generation will most likely depend on how you would be using the generated code. You had stated that your application is intended to essentially analyze/visualize the outputs of simulink models. Do you intend for you application, itself, to be a Simulink model? If so, I imagine your workflow would be that you generate code for the "plug-in" model and then incorporate this into your "parent" model as an s-function. Based on the descriptions given above, my gut feeling is that you would not see much of a performance improvement compared to accelerator mode.
However, if your application is to be implemented outside of Simulink, then code generation would definitely be the way to go. In this case, you've completely eliminated the overhead of communicating with Simulink. In this workflow, you could, for example, generate a stand-alone executable from the "plug-in" model, execute that model to get the outputs, and then simply load those outputs for analysis and visualization into your application. Your application could be written in any language you want. In fact, you could even still write your application in MATLAB -- the key point, though, being that your application runs once the stand-alone executable (generated from the "plug-in" model) has finished executing, rather than interfacing with the plug-in model while it is executing.
As far as I know, stateflow and simulink are often used at the same time, and are both environments developed by MathWorks, who make Matlab. May I know what's the difference between them?
Simulink is largely a controls oriented solution. It graphically depicts math like products, sums, integrals, etc. However, it's conditional logic facility is lacking. Any kind of if construct quickly becomes terse and unmanageable in my opinion. I've seen many models, and there is a clear line here where Simulink should end and Stateflow should start.
Stateflow deals extremely well with logic and, of course, state machines. Now with the addition of the Simulink Function blocks within Stateflow, we have a powerful combination to allow the state machine in Stateflow direct the rest of the program.
As far as functionality goes, they are both functionally complete, meaning anything you can code in C, you can code in Simulink or Stateflow. However, I would not recommend coding a PID loop in Stateflow, but it's possible. You could also easily create a state machine in Simulink, but I'd advise against it.
As far as code generation; in the beginning of the meld, the Stateflow and Simulink had separate code generators that were sewed together with more Simulink generated C code at code generation time. Then came CGIR (Code Generation Intermediary Representation), which unifies the code generator between Stateflow and Simulink. It came around 2007, and has continued to deliver substantial increases in performance. Generated code has increased in on target performance to a point where companies can use the code in their embedded systems and actually get a performance benefit rather than take a small hit. Also, the time to generate the code has also decreased substantially. CGIR is a replacement for the Target Language Compiler, however, never fear, TLC API will still be available, perhaps forever for those who have developed massive libraries of proprietary code generation libraries.
Hope this helps, let me know if something sounds fishy or if I need to clarify.
Quoting a Stateflow Webinar:
Simulink is used to respond to continuous changes in dynamic changes.
Stateflow is used to respond to instantaneous changes in dynamic changes.
Real-world systems have to respond to both continuous and instantaneous changes.
Use both Simulink and Stateflow so that you can use the right tool for the right job. Examples: Suspensions dynamics of a car are modelled with Simulink whereas, the gear transmission is modelled with Stateflow.
Learn more about Stateflow in general at:
http://www.mathworks.com/products/stateflow/examples.html
Stateflow has been updated for making it very easy to create state machines and flow charts in R2012b.
The major updates include a new graphical editor, state transition tables, MATLAB as the action language and an integrated debugger. Find short videos for these features and how they can be used at:
http://www.mathworks.com/products/stateflow/whatsnew.html
best,
Siddharth
I'm also currently involved with both simulink and stateflow. Till now I did everything in Simulink but once you have to implement logic( if, case) your model becomes visually difficult to be analysed after coding. But I think theoretically you can do everything also just in Simulink (correct me if I'm wrong).
The answer of macduff explains very good the differences.
Regards,
GR
I have worked on both on simulink and state flow environment both are Matlab tool. When u want to design a reactive system or event driven system at that time we should prefer stateflow instead of simulink.
because we can control an event in stateflow in better way compare to simulink .though debugging is easy in simulink but readability and code generation are easy in stateflow.
Complex state machine: Stateflow
Complex mathematical process: Simulink blocks
Others: both of Stateflow and Simulink are fine
Another major benefit of Stateflow is the integration and usage of external C code. This can be done by selecting the Action Language C within the Chart settings.
As commonly known the user can include external Code within the "Simulation Target" options. While a normal Simulink model need small workarounds to access the external C code (ceval(), Simulink.Parameter for globals etc.), Stateflow can directly access functions, defines, etc.
Problems like array of buses/structs can also be avoided by coding these arrays in external code.
For a lot of use cases I love the flexibility to directly interact with C code within Stateflow.