Simulink® provides an application programming interface, called the block run-time interface, that enables programmatic access to block data, such as block inputs and outputs, parameters, states, and work vectors, while a simulation is running. You can use this interface to access block run-time data from the MATLAB® command line, the Simulink Debugger, and from Level-2 MATLAB S-functions (see Write Level-2 MATLAB S-Functions).
Note You can use this interface even when the model is paused or is running or paused in the debugger.
The block run-time interface consists of a set of Simulink data
object classes (see Data Objects) whose instances provide
data about the blocks in a running model. In particular, the interface
associates an instance of
called the block's run-time object, with each nonvirtual block in
the running model. A run-time object's methods and properties provide
access to run-time data about the block's I/O ports, parameters, sample
times, and states.
Every nonvirtual block in a running model has a RuntimeObject
parameter whose value, while the simulation is running, is a handle
for the blocks' run-time object. This allows you to use
get_param to obtain a block's run-time
object. For example, the following statement
rto = get_param(gcb,'RuntimeObject');
returns the run-time object of the currently selected block. Run-time object data is read-only. You cannot use run-time objects to change a block's parameters, input, output, and state data.
Virtual blocks (see Nonvirtual and Virtual Blocks)
do not have run-time objects. Blocks eliminated during model compilation
as an optimization also do not have run-time objects (see Block reduction).
A run-time object exists only while the model containing the block
is running or paused. If the model is stopped,
One application for the block run-time API is to collect diagnostic
data at key points during simulation, such as the value of block states
before or after blocks compute their outputs or derivatives. The block
run-time API provides an event-listener mechanism that facilitates
such applications. For more information, see the documentation for
For an example of using method execution events, enter
at the MATLAB command line. This Simulink model contains
which performs a system identification to determine the coefficients
of an FIR filter. The S-function's
initializes the block run-time object's DWork vector such that the
second vector stores the filter coefficients calculated at each time
In the Simulink model, double-clicking on the annotation
below the S-function block executes its
This function first opens a figure for plotting the FIR filter coefficients.
It then executes the function
PostOutputs method execution event to the
S-function's block run-time object using the following lines of code.
% Add a callback for PostOutputs event blk = 'sldemo_msfcn_lms/LMS Adaptive'; h = add_exec_event_listener(blk, ... 'PostOutputs', @plot_adapt_coefs);
plot_adapt_coefs.m is registered
as an event listener that is executed after every call to the S-function's
The function accesses the block run-time object's DWork vector and
plots the filter coefficients calculated in the
The calling syntax used in
the standard needed for any listener. The first input argument is
the S-function's block run-time object, and the second argument is
a structure of event data, as shown below.
function plot_adapt_coefs(block, ei) %#ok<INUSD> % % Callback function for plotting the current adaptive filtering % coefficients. stemPlot = get_param(block.BlockHandle,'UserData'); est = block.Dwork(2).Data; set(stemPlot(2),'YData',est); drawnow('expose');
You can use run-time objects to obtain the value of a block output and display in the MATLAB Command Window by entering the following commands.
rto = get_param(gcb,'RuntimeObject') rto.OutputPort(1).Data
However, the displayed data may not be the true block output if the run-time object is not synchronized with the Simulink execution. Simulink only ensures the run-time object and Simulink execution are synchronized when the run-time object is used either within a Level-2 MATLAB S-function or in an event listener callback. When called from the MATLAB Command Window, the run-time object can return incorrect output data if other blocks in the model are allowed to share memory.
To ensure the
Data field contains the correct
block output, open the Configuration Parameters dialog box, and then
clear the Signal storage reuse check box on the All
Parameters tab (see Signal storage reuse).