Automate Tagging with Autogen Properties in AutoCAD P&ID

One feature that has quickly become a favorite of mine is automatically incrementing tags on equipment and valves in AutoCAD P&ID.



An autogen property is a value that gets incremented automatically as items are added.  For example, for those who want each valve to have a unique id, an autogen property would be ideal to create these.

To view the current autogen properties, right-click on a drawing in the project manager and go to Drawing Autogen Properties.


In my project, the current properties are a LastLineNumber and a LastValveNumber.


As you can see, you can set the last used value and an increment value to decide where the program will number from.


The nice thing is that AutoCAD P&ID will flag you if you try to use a value that has already been used before.

In this example, I’ve already used “3” in my Line number field so I get the Tag Already Assigned warning.



Setting up an Autogen Property

Let’s walkthrough creating an Autogen property for an Equipment number.  In my project, I’ve already set up a field that uses the drawing number for the first part of the tag. I will need to use an autogen property to fill out the rest of the tag for me as I place new items.

Select the Equipment category from the tree, select an equipment tag, and then click Modify.


Click the Expression button for the Number:


Check the Autogenerate Expression box, select drawing and click the drawing icon.


Click New and add the LastEquipmentNumber field.


Make sure to tell it how many numbers it should use:


Go back to the Project Manager, right-click on the drawing and select Drawing Autogen properties, and set your last used value and the increment.


If you use 0, your first piece will be one:


and your next 2:


and so on!

Setting up Autogen for as many number properties as possible is the way to go to save yourself data entry time and errors.

3 thoughts on “Automate Tagging with Autogen Properties in AutoCAD P&ID

  • Terry Gorseth


    Autogen properties is an awesome feature of AutoCAD P&ID but what if you have say 500 unique tags and 20 have been deleted. Is there a way to manually input the missing numbers back in and then continue the autogen properties for the new tags?? It seems like the autogen will continue adding the next number and you would not be able to return to the deleted numbers.


    • I haven’t seen a way to do that. You should be able to reset the last used value, but it doesn’t appear that setting it to an early value allows it to find skipped numbers.

  • Karren Barlow


    Thanks! I have also found some great P&ID Diagram Examples using Lucidchart and they are very easy to use! Give it a try!

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