get_param

You can get the value of a block parameter using the get_param function with these input arguments:

For more information about block handles and paths, see Get Handles and Paths.

In this example, you get the coefficients of the transfer function specified by a Transfer Function block named Alpha-sensor Low-pass Filter.

Open the example. Then, load the slexAircraftExample model.

mdl = 'slexAircraftExample';
load_system(mdl)

Get the transfer function coefficients.

path = [mdl,'/Controller/Alpha-sensor Low-pass Filter'];
num = get_param(path,'Numerator')

num = 
'[1]'

denom = get_param(path,'Denominator')

denom = 
'[Tal,1]'

When the block path is long and you want to get multiple parameters, consider using block handles.

You can get the value of a block parameter using the get_param function with these input arguments:

In this example, you get the coefficients of the transfer function specified by a Transfer Function block named Alpha-sensor Low-pass Filter.

Open the example. Then, get the block handle using the getSimulinkBlockHandle function. To simultaneously get the block handle and load the model, specify the second argument for the getSimulinkBlockHandle function as true.

path = 'slexAircraftExample/Controller/Alpha-sensor Low-pass Filter';
h = getSimulinkBlockHandle(path,true)

h = 
490.0016

To get the parameter values, specify the block using the handle. Do not manually enter the value of the handle. The value output by the getSimulinkBlockHandle function in the MATLAB® Command Window may not match the handle value due to rounding. Instead, assign the handle to a variable, then use the variable name to specify the block. In this example, the value is assigned to the variable named h.

num = get_param(h,'Numerator')

num = 
'[1]'

denom = get_param(h,'Denominator')

denom = 
'[Tal,1]'

You can get the value of a block parameter using the get_param function with these input arguments:

This example shows how to get the parameter name.

Suppose you want to get the transfer function coefficients of the Transfer Function block named Alpha-sensor Low-pass Filter in the slexAircraftExample model. To do so, you must get the names of the parameters that store the transfer function coefficients.

Open the example.

Get the handle of the Transfer Function block named Alpha-sensor Low-pass Filter. To simultaneously get the block handle and load the model, specify the second argument for the getSimulinkBlockHandle function as true.

path = 'slexAircraftExample/Controller/Alpha-sensor Low-pass Filter';
h = getSimulinkBlockHandle(path,true);

Get the names of all the block parameters of the Transfer Function block named Alpha-sensor Low-pass Filter using the get_param function.

get_param(h,'DialogParameters')

ans = struct with fields:
                    Numerator: [1×1 struct]
                  Denominator: [1×1 struct]
          ParameterTunability: [1×1 struct]
            AbsoluteTolerance: [1×1 struct]
    ContinuousStateAttributes: [1×1 struct]

The output shows that the transfer function coefficients are specified using a Numerator parameter and a Denominator parameter. Use these parameter names to get the coefficients in the numerator and denominator of the transfer function.

num = get_param(h,'Numerator');
denom = get_param(h,'Denominator')

denom = 
'[Tal,1]'

You can get the value of a block parameter using the get_param function with these input arguments:

This example shows how to get the full block path of all blocks in a model with a certain keyword in their name. For more information about how to get block paths, see Get Handles and Paths.

Suppose you want to get the transfer function coefficients of all Transfer Function blocks that act as filters in the slexAircraftExample model.

Open the example. Then, load the slexAircraftExample model.

mdl = 'slexAircraftExample';
load_system(mdl)

Get the paths of all blocks in the slexAircraftExample model whose name contains the word filter using the find_system function. Use regular expressions, make the search case insensitive, and limit the search to blocks. To use regular expressions, set the value of the Regexp parameter to 'on'. To make the search case insensitive, set the value of the CaseSensitive parameter to 'off'. To limit the search to blocks, set the value of the Type parameter to 'Block'.

paths = find_system(mdl,Regexp='on',CaseSensitive='off',Type='Block',Name='.*filter.*')

paths = 3×1 cell
    {'slexAircraftExample/Controller/Alpha-sensor↵Low-pass Filter'}
    {'slexAircraftExample/Controller/Pitch Rate↵Lead Filter'      }
    {'slexAircraftExample/Controller/Stick↵Prefilter'             }

When you do not specify a search depth, the find_system function finds all blocks in the specified level of the model hierarchy and in all lower levels the specified level contains. Since slexAircraftExample is the top level of the model hierarchy, the command returns all blocks from every level of the model hierarchy.

Use the block paths to get the transfer function coefficients. For example, use these commands to get the transfer function coefficients for the Alpha-sensor Low-Pass filter.

num = get_param(paths{1},'Numerator')

num = 
'[1]'

denom = get_param(paths{1},'Denominator')

denom = 
'[Tal,1]'

Get a list of the types of blocks in the vdp model.

Open the example. Then, load the vdp model.

load_system('vdp')

Get a list of block paths and names for the vdp model.

blockpaths = find_system('vdp','Type','Block');

For each block in the vdp model, get the value of the BlockType parameter.

blocktypes = get_param(blockpaths,'BlockType')

blocktypes = 12×1 cell
    {'CustomCallbackButton'}
    {'Constant'            }
    {'SubSystem'           }
    {'Product'             }
    {'Scope'               }
    {'Math'                }
    {'Sum'                 }
    {'Sum'                 }
    {'Integrator'          }
    {'Integrator'          }
    {'Outport'             }
    {'Outport'             }

You can get the value of a model parameter using the get_param function with these input arguments:

The value of the IntegerOverflowMsg parameter indicates how a model handles integer overflow. The model can output no message, a warning message, or an error message.

Suppose you want to compare the value of the IntegerOverflowMsg parameter of two models.

Open the example. Then, load the vdp and f14 models.

load_system({'vdp','f14'})

Get the value of the IntegerOverflowMsg parameter for the vdp and f14 models.

vdpval = get_param('vdp','IntegerOverflowMsg');
f14val = get_param('f14','IntegerOverflowMsg');

When integer overflow occurs, the vdp model outputs a warning, while the f14 model does not output any message.

Compare the two parameter values using the strcmp function.

strcmp(vdpval,f14val)

ans = logical
   0

The strcmp function outputs 0, which indicates that the two models have different values for the IntegerOverflowMsg parameter.

You can get the value of a model parameter using the get_param function with these input arguments:

Suppose you want to compare the message parameter values of two models to ensure consistency in terms of which situations are handled with no message versus a warning message versus an error message. However, you do not know the names of all the message parameters.

Open the example. Then, load the vdp and f14 models.

load_system({'vdp','f14'})

Get a list of all model parameters.

params = get_param('vdp','ObjectParameters');

The function returns a structure. Create a cell array that contains the model parameter names.

names = fieldnames(params);

Message parameters end in the abbreviation Msg. Get the all model parameter names that contain the abbreviation Msg.

msgnames = names(contains(names,'Msg'));

Compare the message parameter values of the vdp and f14 models. Output the names of the parameters that have different values.

vdpval = cell(1,length(msgnames));
f14val = vdpval;

for i=1:length(msgnames)
    vdpVal{i} = get_param('vdp',msgnames{i});
    f14Val{i} = get_param('f14',msgnames{i});
    if(strcmp(vdpVal{i},f14Val{i})<1)
        disp(msgnames{i})
    end
end

IntegerOverflowMsg
IntegerSaturationMsg

Two message parameters have different values.

To get a list of options for any of these, use the get_param function with the keyword options:

This example shows how to get a list of options for a block parameter, a masked parameter, and a model parameter.

load_system('vdp')

funcoptions = get_param('vdp/Square','options@OutputSignalType')

funcoptions = 1×3 cell
    {'auto'}    {'real'}    {'complex'}

get_param('vdp/Mu','options@Permissions')

ans = 1×3 cell
    {'ReadWrite'}    {'ReadOnly'}    {'NoReadOrWrite'}

get_param('vdp','options@AlgebraicLoopMsg')

ans = 1×3 cell
    {'none'}    {'warning'}    {'error'}

h = find_system(gcs,'FindAll','on','Type','annotation');

get_param(h,'PlainText')

ans = 3×1 cell
    {'Copyright 2004-2024 The MathWorks, Inc.'}
    {'Van der Pol Equation'                   }
    {'x_1' =x_2↵↵x_2' =µ(1-x_1^2) x_2 - x_1'  }

get_param(h(2),'options@HorizontalAlignment')

ans = 1×3 cell
    {'left'}    {'center'}    {'right'}

You can access the value of a masked block parameter using the get_param function with the keyword value.

Open the example. Then, open the vdp model.

open_system('vdp')

Get the value of the gain parameter of the masked Subsystem block named Mu.

get_param('vdp/Mu','value@gain')

ans = 
2

In the model, double-click the block.

On the mask, move the slider that changes the gain parameter.

Get the value of the gain parameter again.

get_param('vdp/Mu','value@gain')

ans = 
2

Get the name and value of a global parameter.

load_system('vdp')

modelparamnames = fieldnames(get_param('vdp','ObjectParameters'));

rootparamnames = fieldnames(get_param(0,'ObjectParameters'));

globalparamnames = setdiff(rootparamnames,modelparamnames);

globalparamval = get_param(0,'CurrentSystem')

globalparamval = 
'vdp'