Implementing Off Page Connectors in AutoCAD P&ID

This time of the year is typically pretty hectic. Over the last couple months I did training for companies in Atlanta, Denver, and Houston. And of course we were at AU 2012. All that to say, sorry for not posting!

Today’s article is one topic we get asked about pretty frequently, and is one of the first customization topics clients approach.

In another post I will show how our PDO Extended Fields plugin allows you more accuracy and flexibility for including equipment tags, but this post will start off with the basics.

To customize our off page connectors, we will follow these steps:

  • Decide which attributes we need to show in our connector.
  • Create a new symbol style.
  • Modify the block associated with the symbol style.
  • Test our new Symbols

Lastly we’ll discuss some advanced options for your tags.

Remember to switch your tool palettes to the appropriate group for your project.


Deciding on Attributes

Personally, I like to include the connected Equipment, the line number tag, and the connected drawing name.  Including these will force us to create a From Off Page Connector and a To Off Page connector so that we can use different attributes from the line.

Create a new Symbol Style

The class we are concerned with is under P&ID DWG Settings > P&ID Class Definitions > Non-Engineering Items > Connectors > Off Page Connector


With this class selected, click Add Symbols.  I recommend starting off with a copy of the existing block. You can copy/paste in line work from an existing block at a later point, but it helps us start off with the right attribute properties to work off the default symbol.

I am also working using the PIP symbol set.

To start off with the default PIP off page connector (OPC), browse to your current project’s projsymbolstyle.dwg.  This file is crucial to storing project settings, so make sure it’s never purged.

The block name is PIP OFF-PLOT CONNECTOR; click Add to select the block.  Click Next.


For the symbol name, From Off Page Connector, and we’ll keep the default settings by clicking Finish now.


Modifying our Symbol Block

With the From Off Page connector symbol selected, click Edit Block.  First, remember that we are in the default opc, so we will use Save As to create a new block.  Click the flyout on the Open/Save Panel and click Save Block As.


Type in OPC – From for the Block Name and click Ok.


You should see something like this:


The AttachmentPointX leaders are called Point parameters.  AutoCAD P&ID uses these to figure out where line should connect to blocks. The blue dimensions are linear parameters and then are associated with stretch actions.

The AutoCAD P&ID uses stretch actions to know what to change if the text overflows the block.

For more information on Dynamic Blocks I recommend checking out Matt Murphy’s class:

In our block we have four attributes that we need to discuss.


The attributes being populated by AutoCAD P&ID/Plant 3D, use a special formatting – #().  When we click the #() button, we get to choose how to populate an attribute or text. The target object property allows use to use a property from more than once class. When we specify a class directly (like the PipeLineGroup.Service) the program will try to use the object’s relationship to locate that property.

The #(=Drawing.General.PnID) is a special value that pulls in the connected P&ID drawing.  You can use any drawing properties, just remember to put the = sign after the first parenthesis  so that the connected drawing is displayed and not the current drawing.


Before testing our block we need to change the Symbol to use the block we created using the Save As.  Click Edit Symbol and select the OPC – From Block. Now, click Add to Tool Palette to add our new symbol to the current tool palette.

Here’s how I configured my OPC. The #(PipeLines.Tag) will put in the line number tag for the line segment that’s connected.  The #(Pipelines.From) will put in the equipment that is connected to the current line segment.


I will repeat the process and create an OPC – To symbols so I can switch the styles of the OPCs as needed.

The final steps is to set the default symbol style for the Off Page Connector Class. With the Off Page Connector Class selected, scroll down to the Graphical Styles Property and select our new From Page Connector Style.


Testing our New Symbol

While we can insert new blocks for testing, we can also switch the style of existing blocks.  Do both to ensure that your symbol behaves as expected.






Advanced OPC’s

Some people like to have a to or from included with their OPC’s. To include those, you can use fill in the attribute with “TO #(=Drawing.General.PnID)” where space is created using a non-breaking space (hold down the Alt key and enter 0160).  You have to do this in an annotation though, as P&ID fills in the symbol with only the property information.


Our video implementing the PDO XF Elevations demonstrates how this can be done in an annotation: Implementing BOP Elevations in Orthographics

In those scenarios, you may want to create some subclasses of the off page connector so that you can define a particular annotation to come in (ie To or From) along with your opc.