Documentation

Create Forwarding Table Programmatically

At the command line, you can create a simple Forwarding Table specifying the old locations and new locations of blocks that have moved within the library or to another library. You associate a forwarding table with a library by setting its ForwardingTable parameter to a cell array of two-element cell arrays, each of which specifies the old and new path of a block that has moved. For example, the syntax to create a forwarding table and assign it to a library named Lib1 is:

set_param('Lib1', 'ForwardingTable', {{'Lib1/A', 'Lib2/A'} 
{'Lib1/B', 'Lib1/C'}});

where:

Transformation Functions

A linked block instance is associated with instance-specific parameters called InstanceData. When you create versions of a library block, parameter sets can get added or removed from the InstanceData.

A transformation function corrects the mismatch of parameters in the InstanceData of the new and old library links thus ensuring that the library links continue to work.

You can define a transformation function using a MATLAB file on the path, then specify the function in the Transformation Function column of the Forwarding Table.

The new block path defined in the forwarding table overrides the values defined in the transformation function. If the new block path is a dynamic value that changes based on certain conditions, then the new block path must be only defined using the transformation function.

The syntax for transformation function must be:

function outData = TransformationFcn(inData)

where:

A general transformation function can have many local functions defined in it. The function calls the appropriate local functions based on old block names and versions. You can use this to combine multiple local functions into a single transformation function, to avoid having many transformation functions on the MATLAB path.

Consider the Compare to Constant block in Simulink^® Library. You must create versions of this block without changing the name and the block path but add the parameters to the newer library block.

The table displays the parameter difference in two versions of the Compare to Constant block.

Block {
BlockType		      Reference
Name		      "Compare\nTo Constant"
Ports		        [1, 1]
Position		     [210, 60, 250, 100]
SourceBlock	  "fixpt_lib_4/Logic & Comparison/Compare\nTo Constant"
SourceType	    "Fixed-Point Compare To Constant"
relop	           "=="
const	           "3.0"
    }

Block {
BlockType		      Reference
Name		      "Compare\nTo Constant"
SID		                      "15"
Ports		                     [1, 1]
Position		      [125, 50, 155, 80]
ZOrder		      -5
LibraryVersion	      "1.271"
SourceBlock	       "simulink/Logic and Bit\nOperations/Compare\nTo Constant"
SourceType	        "Compare To Constant"
relop		          "<="
const		             "3.0"
OutDataTypeStr	      "boolean"
ZeroCross		      on
    }

The new version of the Compare to Constant block has additional parameters (OutDataTypeStr and ZeroCross) associated with it. For such cases, the transformation function must ensure that the additional parameters in the InstanceData are set so that the old library links work.

This example shows a transformation function for the Compare to Constant block to add the OutDataTypestr parameter with a value of uint8.

function [outData] = TransformationCompConstBlk(inData)
outData.NewBlockPath = ''; % No change in the library block path
outData.NewInstanceData = [];
instanceData = inData.InstanceData;
% Get the field type 'Name' from instanceData
[ParameterNames{1:length(instanceData)}] = instanceData.Name;

if (~ismember('OutDataTypeStr',ParameterNames))
    % OutDataTypeStr parameter is not present in old link. Add it and set value uint8
    instanceData(end+1).Name = 'OutDataTypeStr';
    instanceData(end).Value = 'uint8';
end

outData.NewInstanceData = instanceData;