# In SysML ibd, how to create an instance of a block **URL:** \ **Category:** How To\ **Tags:** sysml\ **Created:** [February 8, 2020, 3:45pm UTC](https://forums.visual-paradigm.com/t/in-sysml-ibd-how-to-create-an-instance-of-a-block/15858 "2020-02-08T15:45:27Z")\ **Posts on this page:** 8\ **Page:** 1
**Author:** ![Ishii\_Toshinao](https://forums.visual-paradigm.com/user_avatar/forums.visual-paradigm.com/ishii_toshinao/32/4385_2.png) [@Ishii\_Toshinao](https://forums.visual-paradigm.com/u/Ishii_Toshinao)\ **Post date:** [February 8, 2020, 3:45pm UTC](https://forums.visual-paradigm.com/t/in-sysml-ibd-how-to-create-an-instance-of-a-block/15858/1 "2020-02-08T15:45:28Z")
Hi. I am new to Visual Paradigm SysML modeling, though not so new to SysML modeling. I cannot find how to create an instance of a class defined in an Block Diagram in the model. What I tried was just drag and drop a class in the Model Explorer to an ibd diagram. What happens by this operation is to have the Block, but not an instance of the Block, in the diagram. This is not like the screen shot on [https://www.visual-paradigm.com/features/sysml-diagram-tool/#internal-block-diagram](https://www.visual-paradigm.com/features/sysml-diagram-tool/#internal-block-diagram) . Please let me know the steps to have instances of defined Block in Internal Block Diagram. Thanks in advance. ---
**Author:** ![antony](https://forums.visual-paradigm.com/user_avatar/forums.visual-paradigm.com/antony/32/2411_2.png) [@antony](https://forums.visual-paradigm.com/u/antony)\ **Post date:** [February 10, 2020, 12:58am UTC](https://forums.visual-paradigm.com/t/in-sysml-ibd-how-to-create-an-instance-of-a-block/15858/2 "2020-02-10T00:58:38Z")
Hi Toshinao, By selecting either Part Property, Reference Property, Participant Property from the palette, click on empty area of diagram, you will be prompted to select a Block as the type for the new property. Alternatively, you can change the type of existing property by opening its specification (press Enter key when the property is being selected), and change it in the Type property field. Best Regards, Antony. ---
**Author:** ![Ishii\_Toshinao](https://forums.visual-paradigm.com/user_avatar/forums.visual-paradigm.com/ishii_toshinao/32/4385_2.png) [@Ishii\_Toshinao](https://forums.visual-paradigm.com/u/Ishii_Toshinao)\ **Post date:** [February 10, 2020, 9:11am UTC](https://forums.visual-paradigm.com/t/in-sysml-ibd-how-to-create-an-instance-of-a-block/15858/3 "2020-02-10T09:11:59Z")
Hi Antony, Thanks for comment. What happened to me was, as described in the uploaded image, an error saying “Can only create Part Property on diagram whose parent model element is either Block, Constraint Block or Activity Block”. I guess there’s some ways to set the “parent model element” of ibd, which I cannot find. Please let me now how to do this. ![screenshot_11](https://forums.visual-paradigm.com/uploads/default/original/2X/b/b5eb9c2f3613e140b309fd91d1384ef787bdd5d5.png) ---
**Author:** ![antony](https://forums.visual-paradigm.com/user_avatar/forums.visual-paradigm.com/antony/32/2411_2.png) [@antony](https://forums.visual-paradigm.com/u/antony)\ **Post date:** [February 10, 2020, 9:52am UTC](https://forums.visual-paradigm.com/t/in-sysml-ibd-how-to-create-an-instance-of-a-block/15858/4 "2020-02-10T09:52:06Z")
Hi Toshinao, If you create an ibd via new diagram dialog you should be forced to create it under Block or Constraint Block already, but if you create the ibd via Model Explorer’s popup menu this checking is omitted. To move ibd under a Block, right-click on it in Model Explorer, select Sub Diagrams \> Existing Diagrams, and then add that ibd to make it sub-diagram of the Block. You can reference section " Add an existing diagram as a sub-diagram" in this documentation for details: [https://www.visual-paradigm.com/tutorials/how-to-use-subdiagrams.jsp](https://www.visual-paradigm.com/tutorials/how-to-use-subdiagrams.jsp) Hope this helps, Antony. ---
**Author:** ![Ishii\_Toshinao](https://forums.visual-paradigm.com/user_avatar/forums.visual-paradigm.com/ishii_toshinao/32/4385_2.png) [@Ishii\_Toshinao](https://forums.visual-paradigm.com/u/Ishii_Toshinao)\ **Post date:** [February 10, 2020, 12:10pm UTC](https://forums.visual-paradigm.com/t/in-sysml-ibd-how-to-create-an-instance-of-a-block/15858/5 "2020-02-10T12:10:57Z")
Thanks. It works fine. I’ve got a new question, which came up with naturally. Suppose there’s a common library of Blocks which is external to an ibd’s parent Block, how can one use it in the ibd ? I guess ibd can have more than one parent diagrams. ---
**Author:** ![antony](https://forums.visual-paradigm.com/user_avatar/forums.visual-paradigm.com/antony/32/2411_2.png) [@antony](https://forums.visual-paradigm.com/u/antony)\ **Post date:** [February 11, 2020, 12:45am UTC](https://forums.visual-paradigm.com/t/in-sysml-ibd-how-to-create-an-instance-of-a-block/15858/6 "2020-02-11T00:45:29Z")
Hi Toshinao, Then you can refer to my first reply - though create an ibd requires you to specify a block as parent, creating properties (part/reference/participant) you can select any block you want, it isn’t bound to selecting the parent block of the ibd. And in Visual Paradigm, a diagram can have only one parent, or none which the diagram is said to be in root level. Best Regards, Antony. ---
**Author:** ![Ishii\_Toshinao](https://forums.visual-paradigm.com/user_avatar/forums.visual-paradigm.com/ishii_toshinao/32/4385_2.png) [@Ishii\_Toshinao](https://forums.visual-paradigm.com/u/Ishii_Toshinao)\ **Post date:** [February 11, 2020, 5:37am UTC](https://forums.visual-paradigm.com/t/in-sysml-ibd-how-to-create-an-instance-of-a-block/15858/7 "2020-02-11T05:37:21Z")
Hi Antony, Thank you. I understand that, although each ibd is a child of a diagram, it can refer any model element under the top level. ---
**Author:** ![antony](https://forums.visual-paradigm.com/user_avatar/forums.visual-paradigm.com/antony/32/2411_2.png) [@antony](https://forums.visual-paradigm.com/u/antony)\ **Post date:** [February 11, 2020, 5:46am UTC](https://forums.visual-paradigm.com/t/in-sysml-ibd-how-to-create-an-instance-of-a-block/15858/8 "2020-02-11T05:46:47Z")
That’s right, if a model property refers to another model element (like Property’s Type property), it usually wouldn’t bound to selecting those under the same parent.