Nate Holt's Blog

October 16, 2010

Tutorial – Terminal Strip Management (Part 1) – AutoCAD Electrical

Filed under: Electrical, Tutorials — nateholt @ 5:31 pm

Autodesk’s Nathan Eliason hosted a webcast earlier this week that focused on AutoCAD Electrical’s ability to insert, track, and manage terminal blocks / terminal strips in a project drawing set. I helped put the demo together and was responsible for real-time Q & A support while Nathan was “on stage”. 

Also thanks to Doug McAlexander for some of the images and samples.

This posting is a brief summary of what Nathan covered in the first half of the hour-long webcast. This part deals with the “schematic” end of things… inserting and tracking terminal assignments in electrical schematics. The second part (to be posted soon), deals more with the panel layout end of things and focuses on the AutoCAD Electrical “Terminal Strip Editor” tool.

Hopefully this posting can serve as a simple overview / tutorial of this AutoCAD Electrical feature.

The above looks simple enough, right? Wire goes in. Wire comes out. Put a number on the little label between the two screws. That’s the physical part and it doesn’t look too complicated…

And above, on the electrical schematic, wire coming in, wire coming out, terminal label in the middle. Looks simple enough. How can this be complicated?

At least seven complicating factors… not to mention the sheer number of terminals that may end up in an electrical controls design.

 Let’s start at the top and look at terminal behavior and terminal numbering supported by AutoCAD Electrical. There are three different types of schematic terminal behaviors supported by AutoCAD Electrical.

Type 1 – Terminal with fixed, assigned number

Here is the first type of schematic terminal symbol… shown here as a round symbol with text. These terminal symbols can be of various shapes… but they are all just simple AutoCAD blocks with certain key attributes. More on this in a bit.


Key characteristics of this “Type 1” terminal symbol:  it carries an assigned terminal number value; it maintains the wire number through the terminal; it carries a “terminal strip” assignment; it can carry a part number assignment.

Type 2 – same as type 1 but forces wire number change through it

Here is an example of the second type of schematic terminal. Same as type 1 but this one triggers AutoCAD Electrical to generate a wire number change through it. The type 1 terminal simply maintained its attached wire number through it – wire number coming in was the same leaving. Here, for type 2, it changes

Key characteristics:  it carries an assigned terminal number value; it triggers a wire number change from one side of the terminal to the other; it carries a “terminal strip” assignment; it can carry a part number assignment.

Below is a “worst case” version of this second type of terminal. There are five wires tied to the four wire connection points carried on the terminal symbol.

Note that AutoCAD Electrical has generated four unique wire numbers. Why not five? This is because two of the wires come together at a common wire connection point on the terminal symbol. These two wires do not actually “to through” the terminal and wire the number does not change between them.

Type 3 – automatically takes on wire number that passes through it

This terminal type takes on a copy of the connected wire number as its displayed terminal number.

Key characteristics:  it automatically carries a terminal number equal to the wire number that passes through the terminal;  it maintains the wire number through the terminal (not like Type 2); it carries a “terminal strip” assignment; it can carry a part number assignment.

 Note in the example above it’s a bit cluttered. We have the wire number shown on the type 3 terminal but we also have the wire number shown on the wire itself. Is there a good way to suppress this default AutoCAD Electrical behavior regarding wire numbers tied to type 3 terminals?…


This project-wide setting (below) can be set to suppress wire number text from appearing on a wire network that has a “wire number” type terminal somewhere in it. The wire numbers on these networks are flipped to layer “WIRENO_HIDE” which is then marked “frozen”. What remain are the wire numbers shown on the wire number terminals (and any wire numbers on networks without any wire number terminals).

To enable this project-wide mode of operation, right-click on the active project in the AcadE “Project Manager” dialog and make the selection as shown above. This does not take effect until wire numbers are inserted or freshened on the project’s drawings.

 Note: this feature works on “normal” wire numbers only… it does not move “Fixed” wire numbers to the WIRENO_HIDE layer. To hide a “fixed” wire number, use the “Hide” Wire Number command or “Hide Attribute” command.

The three different behaviors of terminals (wire number, terminal number, and whether terminal breaks the wire number through it) are controlled by the terminal block name and presence or absence of certain attributes.

 The two terminal number symbols are essentially identical except for the 3rd character of the block name. If the 3rd character is a “0” then the wire number does not change through the symbol. If it is a “1” then this causes the symbol to trigger a wire number change through it.

Schematic Terminal selection – via Icon Menu pick

So how do I select my terminal type and terminal shape so I can insert these things into my schematics?

The three different terminal types are selectable in various shapes on the icon menu. Here is how to launch the icon menu from the “Schematic” section of the ribbon menu…


… and then picking on the “Terminals/Connectors” main icon brings up the page below for selection of the individual terminal symbols.


The first column above shows just “dumb” terminal representations. These are not tag-able or extractable into reports. The 2nd, 3rd, and 4th columns show terminals based upon wire number, terminal number, and terminal number that triggers a wire number change through the terminal symbol.

Demo example

Let’s try it on this schematic below.  Three 3-phase motor starter circuits are shown. For each of these motors, let’s add some square terminal symbols between the overload symbol and the left-hand side of the field disconnect switch.

Launch the schematic Icon Menu and drill down to the square terminal with terminal number in screen-shot below. Pick it and pop it in right on the upper phase wire of the first motor circuit.

The square terminal pops in and breaks and reconnects the wires. The existing wire number re-centers itself. An edit dialog pops up.

Here, enter “TB-1” for the terminal strip “Tag Strip:” name. Enter “1” as the terminal “Number:”.

 Now, to save time, hit “OK-Repeat”. This keeps us “in the command” and let’s us pop in the 2nd square terminal immediately (instead of having to reselect from the icon menu).  With each “OK-Repeat” selection, the dialog pops up with the previous selections except for the “Number:” entry. It auto-increments to the next available terminal sequential number.  After the 3rd terminal insert, exit the dialog with “OK” instead of “OK-Repeat” and the command will exit its “looping” and return to the AutoCAD “Command:” prompt.

Using Fence Insert for Incrementing terminal inserts

That was easy, but maybe a bit tedious. Let’s use a different approach to insert nine “TB-2” square terminals on the next three motor circuits.

Start the “Icon Menu” but do it from the “Multiple Insert (Icon Menu)” button shown here. Pick the square terminal from the Icon Menu, just like before…

… but you get kicked into a “Fence” crossing mode. Draw a fence crossing all nine wires of the three motor circuits below.

A square terminal pops in at the very first fence crossing point with a wire. We hit “OK” to keep this one.

The normal Insert/Edit Terminal dialog pops open. Enter “TB-2” for the terminal strip’s “Tag Strip” name and enter “1” as the very first terminal number. Hit “OK” to exit the dialog and move on to the next.


The initial terminal is now inserted at the first fence crossing point. It has the tag “TB-2” and starting at terminal “1”.

Now, for the remaining eight terminals, we can just pre-select “Keep all, don’t ask” and turn off the “Show edit dialog” option. Hit “OK” and let it rip.


And there they are!

Managing next available terminal for a given terminal strip

To finish up, let’s insert three terminals on the bottom motor. But let’s tie them to the next available terminals on “TB-1” (not “TB-2”).

Use the “Multiple Insert (Icon Menu)” like last time and select the square terminal again. Draw a fence through the bottom three wires for the last motor circuit.

 The first terminal pops in and dialog shows up. We want “TB-1” but it defaults to “TB-2” which was the last terminal strip we worked on. Flip it to “TB-1” in the lower part of the dialog.


The moment we select “TB-1”, the dialog pre-fills with appropriate information related to this terminal strip. A key piece of data is the next unused terminal number, “4”, automatically filling in to the “Number:” edit box.

 We just hit “OK” and let the three incrementing terminals pop in. So there we are… all five motor starter T-leads have the terminals popped in between the starter overload and the field safety switch.

Wait, what about catalog part number assignments ?!!

We didn’t assign catalog part numbers to the terminals… could we have?, yes. But it sometimes may make better sense to just pop them in and later, at the panel layout stage, make those assignments. This is pretty easy using the “Terminal Strip Editor” tool.

Check out Part 2 for this.


Nate Holt.


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