Control Linked Blocks Programmatically

Find and Modify Library Details of a Linked Block

Load the model and get library details of a specific block referenced in the model.

load_system("sldemo_fuelsys");
linkedBlock = "sldemo_fuelsys/fuel_rate_control/validate_sample_time/CheckRange";
libinfo(linkedBlock)

ans = struct with fields:
             Block: 'sldemo_fuelsys/fuel_rate_control/validate_sample_time/CheckRange'
           Library: 'simulink'
    ReferenceBlock: 'simulink/Model...'
        LinkStatus: 'resolved'

The ReferenceBlock parameter indicates that the Check ↵Static Range block from the Simulink® library is the parent of the linked block CheckRange in the model. To change the ReferenceBlock to Check ↵Dynamic Range, use the set_param function:

set_param(linkedBlock,'ReferenceBlock',...
    ['simulink/Model Verification/Check ',newline,'Dynamic Range'])

Get the library details of the linked block CheckRange in the model.

libinfo(linkedBlock)

ans = struct with fields:
             Block: 'sldemo_fuelsys/fuel_rate_control/validate_sample_time/CheckRange'
           Library: 'simulink'
    ReferenceBlock: 'simulink/Model...'
        LinkStatus: 'resolved'

Lock Linked Blocks

You can lock the links between a parent library block and its linked blocks. When you lock the links to a library, you can no longer edit or disable the links from a library block instance used in a model. This behavior prevents unintentional modifications and enhances the protection of your library blocks.

Use the LockLinksToLibrary parameter to lock or unlock a linked block in a library from the command line.

To lock the links, use:

set_param("MyLibraryName","LockLinksToLibrary","on");

To unlock the links, use:

set_param("MyLibraryName","LockLinksToLibrary","off");

Link Status

Link status provides information about the connection between a referenced block in a model and its corresponding block in a library. You can get the link status of a block in a model by using the LinkStatus and StaticLinkStatus parameters.

• StaticLinkStatus — Indicates the link status of a block without updating the linked blocks. This parameter is useful to query the status of linked blocks that are either active or outdated without changing or updating their current state. To get the StaticLinkStatus, use get_param(gcb,'StaticLinkStatus').

• LinkStatus — Updates the linked blocks and reflects the real-time status of a block. To get the LinkStatus, use get_param(gcb,'LinkStatus').

LinkStatus can have one of these values:

Get LinkStatus Value	Description
none	The block is not a linked block.
resolved	The link to the library block is active and valid.
unresolved	The link to the library block cannot be resolved. For example, the library block is missing or the path is incorrect.
implicit	The block resides within a library block and is not directly linked to a library block itself. For example, if a library subsystem contains a Gain block and this subsystem has a linked block A in a model, when you select the Gain block within the block A in the model, then the get_param(gcb,'LinkStatus') function returns the LinkStatus as implicit.
inactive	The link to the library block is disabled.

You can set the LinkStatus to one of these values using the set_param function. For example, to break a link to the library, use set_param(gcb,'LinkStatus','none').

Set LinkStatus Value	Description
none	Breaks the link to the library block.
breakWithoutHierarchy	Breaks the link without affecting the nested parent hierarchy of the link.
inactive	Disables the link to the library block.
restore	Restores an inactive link to the library block and replaces the version of the linked block in the model with the version in the library. restore discards any changes made to the local copy of the linked block in the model.
propagate	Pushes the changes made to an inactive linked block in a model to its corresponding library block and re-establishes its link. Pushing a link replaces the version of the block in the library with the version in the model.
restoreHierarchy	Restores all disabled links in the link hierarchy to their corresponding library blocks and replaces the version of the linked blocks in the model with the version in the library. For more information on hierarchy mode, see Pushing or Restoring Link Hierarchies.
propagateHierarchy	Pushes all the changes made to the linked blocks in the link hierarchy back to their respective library blocks. Pushing the links replaces the version of the blocks in the library with the version in the model. For more information on hierarchy mode, see Pushing or Restoring Link Hierarchies.

Get and Set Link Status of Linked Blocks

A model LibrariesDemo has four Subsystem blocks.

load_system("LibrariesDemo.slx")

Get the link status of Subsystem block Amplifier 1. Amplifier 1 is not a linked block.

status_1 = get_param("LibrariesDemo/Amplifier 1",'LinkStatus')

status_1 = 
'none'

Get the link status of Subsystem block Amplifier 2. Amplifier 2 is a linked block from a custom library AmplifierLibrary with 'resolved' link status.

status_2 = get_param("LibrariesDemo/Amplifier 2",'LinkStatus')

status_2 = 
'resolved'

Get the link status of Subsystem block Amplifier 3. Amplifier 3 is a linked block from a custom library LibA with 'unresolved' link status as the library is not located at the specified path.

status_3 = get_param("LibrariesDemo/Amplifier 3",'LinkStatus')

Warning: Cannot find library called 'LibA'.  

status_3 = 
'unresolved'

Get the link status of Subsystem block Amplifier 4. Amplifier 4 is a linked block from a custom library AmplifierLibrary with 'inactive' link status.

status_4 = get_param("LibrariesDemo/Amplifier 4",'LinkStatus')

status_4 = 
'inactive'

Restore the link of Amplifier 4.

set_param("LibrariesDemo/Amplifier 4",'LinkStatus','restore')
status_4 = get_param("LibrariesDemo/Amplifier 4",'LinkStatus')

status_4 = 
'resolved'

Get the link status of Gain block in Subsystem block Amplifier 2. The link status of Gain block is 'implicit' as the Gain block resides within a library block and is not directly linked to a library block itself.

status_5 = get_param("LibrariesDemo/Amplifier 2/Gain",'LinkStatus')

status_5 = 
'implicit'

Considerations When Getting Link Status

• When you query the link status of a block using the LinkStatus parameter, any outdated block links are also resolved.

• When get_param is used in the callback code of a child block, it is recommended to use the StaticLinkStatus parameter to query the link status, as StaticLinkStatus does not resolve any outdated links.

• If you use the get_param function on a block that is inside a library link, Simulink^® automatically resolves any necessary links. This process may involve loading parts of the library and executing any associated callback functions.