Nate Holt's Blog

June 23, 2010

Tutorial – Basics of ‘Smart’ Panel Layout (Part 2) – AutoCAD Electrical

Filed under: Electrical, Tutorials — nateholt @ 1:36 pm

Overview of how AutoCAD Electrical can link control schematics to the panel layouts and track what has and has not been inserted.

Autodesk’s Dustin Clark hosted a webcast earlier this month that focused on AutoCAD Electrical’s ‘smart’ panel layout feature. I helped put the demo together and was responsible for real-time Q & A support while Dustin was “on stage”.

This posting is a brief summary of what Dustin covered in the second 10 minutes or so of the hour-long webcast. It might serve as a simple overview / tutorial of this AutoCAD Electrical feature. Note: the first part of the webcast is summarized here:

Tutorial – Basics of ‘Smart’ Panel Layout (Part 1)

So, here we go…

We ended the previous tutorial with showing how a schematic symbol representation is linked to its panel-layout counterpart. This means that editing one representation can trigger automatic update of the other.

So, how is this schematic to panel update made possible?

 The link between schematic and layout versions of the same component is made through nothing more than the tag-ID assignment on each. If the tag-ID assignment matches, then AutoCAD Electrical considers them to be linked.

 What is the tag-ID?  It is an attribute value.

 Yes, an attribute value… AutoCAD Electrical uses normal AutoCAD “blocks” with attributes for both schematic symbols and for panel layout representations.

 And one of the attributes on each type of representation is assigned to carry the component’s tag-ID assignment.

For a schematic component like a relay coil symbol or pilot-light or switch symbol, the tag-ID value is assigned to the “TAG1” attribute.

 For the panel layout component, that tag-ID value is assigned to an attribute called “P_TAG1”.

 So, if a schematic instance of a red pilot-light symbol attribute TAG1 with a value of “LT409” and if a panel layout showing the physical placement of a pilot light carries attribute “P_TAG1” with a value of “LT409”, then this is sufficient for AutoCAD Electrical to consider them “linked”.


SIDEBAR: the more complex IEC-style tagging – how the link is established


If the AutoCAD Electrical project is selected to operate in “IEC tagging mode”, then two more attributes are included to establish the link.

 These are attribute “INST” for an IEC installation assignment and “LOC” for an IEC location assignment.

 In this example, the schematic relay symbol carries three attributes INST, LOC, and TAG1 with values “L2”, “MC”, and “K14” respectively. These values are concatenated into a full tag-ID string of “=L2+MC-K14”. It is this full, concatenated tag-ID that must match up between a symbol on the schematic and a physical representations on a layout drawing – when match, then AutoCAD Electrical considers the pair of components as linked.

 So, summarizing, in normal mode (i.e. non-IEC tagging mode), it’s just a match on the one attribute. In IEC mode, it is a combined match on the three attributes.


Once schematic and panel representations are linked with the common, unique tag-ID value, this makes possible the following:

  1. Update description or rating attribute values
  2. Change catalog assignment on one can update the other. If the catalog assignment change means that the physical layout symbol needs to change, this update can happen as well.
  3. Re-tagging  one will update the other.
  4. Deleting one will prompt for permission to delete the other.
  5. Schematic wire connection information can be automatically pushed to annotate a “wiring diagram” version of a panel layout representation.


Question: Link requires matching tag-ID text… does this mean I need to enter the same tag-ID two times? One time on the schematic representation and then, when I insert my panel footprint for that component, I need to remember what I used so that I can put the same tag-ID attribute value on the panel?

 Answer: No. You don’t have to enter the data twice. With AutoCAD Electrical you just pick from a display list.


Let’s say that you have pretty much finished the first pass of your schematic design. Now you’re ready to start laying out the control panel. What tools are available in AutoCAD Electrical to help move things along with the panel layout and also reuse as much data from the schematic as possible?

 Let’s look at the insert panel footprint from “Schematic List” tool.

 This extracts a list of parent schematic components found on the schematic drawings and presents this in a pick list dialog (below). 


Now, with the list of schematic components displayed…

… you pick on the schematic entry for a target component. The tool attempts to find the appropriate physical footprint representation for it based upon the schematic symbol’s catalog part number assignment (assuming that this part number assignment was already defined on the schematic representation).

If the appropriate footprint block symbol is found, the command grabs a copy and then prompts you for where you want to place it in the panel layout.

You pick the position. AutoCAD Electrical pops it in. Then it copies the schematic data over to this newly insert panel representation. This data includes a copy of the schematic symbol’s tag-ID attribute value.

In this way the link between the schematic representation and the physical layout representation is automatically established without the need to enter the same data a second time. The tag-ID value pulled from the schematic version and listed in the pick list is then pushed across to the P_TAG1 attribute on the panel footprint representation. Results in matching tag-IDs between the two representations… and therefore enables the bi-directional update between them when you make an edit to one or to the other.


Additional bonus… as you go along, AutoCAD Electrical tracks what schematic components have been inserted into the panel layout by placing an “x” in the first column of the display list above.

That’s it for this posting. Much more to come in “Part 3”.

Tutorial: Smart Panel Layout – Part 1 can be accessed here.



  1. part 1 and part 2 was so usefull to me. Now I understand how schematic and panel are linked. I thank you so much for the explanation. One thing yet not clear to me that is : is the panel placed in the same schematic file or schematic has a file and panel has another file? and how autocad electrical understands the panel size?

    Comment by imad — August 17, 2010 @ 5:54 pm

  2. […] Tutorial – Basics of ‘Smart’ Panel Layout (Part 2 – tracking schem versus panel representati… […]

    Pingback by Tutorial – Automation of PLC I/O Drawings – AutoCAD Electrical « AutoCAD Electrical Etcetera — September 1, 2010 @ 3:36 pm

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