Nate Holt's Blog

May 6, 2010

Tutorial – AutoCAD Electrical and contact pin assignments

Filed under: Electrical, Tutorials — nateholt @ 4:48 pm

Real-time tracking of device contact type and contact pin assignments with AutoCAD Electrical.  

Autodesk’s Nathan Eliason hosted a webcast last month that focused on AutoCAD Electrical’s contact and pin assignment tracking features. I helped put the demo together and was responsible for the real-time Q & A support while Nathan was “on stage”.  

This posting is a brief summary of what Nathan demonstrated in the opening minutes of the webcast. It might serve as a simple tutorial of the basics of this AutoCAD Electrical feature.  

Related tutorials: Off-beat Uses of Toggle NO/NC Command, Tutorial – Setting Up New Device “Pin List”


Modern PLCs have greatly reduced hard-wired control panel logic. A large part of your controls logic might eventually be held and fully documented within the PLC processor itself. But instances of discrete, hard-wired devices such as relays and contactors often remain a part of the design. What follows is a brief summary of AutoCAD Electrical’s capabilities in this area. 


Component Tag-ID and Contact assignments 

There are at least two categories of data that we need to track regarding relay, contactors, and like items. First, we need to assign unique tag-IDs to key control components. This helps with mapping the schematic representation of a component with its physical layout representation. It also allows multi-element components such as our relays and contactors to have their “child” contact parts linked back to a “parent”.  AutoCAD Electrical handles this component tagging task nicely.  

But in the examples below we’re going to focus on the more complex second category of data tracking… dealing with catalog part number assignments and then tracking child contact counts and wire connection pin number assignments.  AutoCAD Electrical handles this second task nicely as well.  

Catalog Lookup / Contact Count / Pin List 

So, how does AutoCAD Electrical assist us in this catalog assignment and contact count and pin number tracking task for a newly-inserted or edited relay coil symbol?  

Let’s follow the sequence. Using the normal AutoCAD Electrical icon menu selection, we pop a generic relay coil symbol into a wire in the schematic. The “Insert/Edit Component” dialog appears with a generated tag-ID. Okay, that’s the easy part… the unique tag-ID.  


Now let’s move on to a catalog assignment. Pick on the “Lookup” button. AutoCAD Electrical opens the Parts catalog database dialog with only relay information displayed (because we’re inserting / editing a relay symbol).  Here we select “AB” (Allen-Bradley) from a number of supported manufacturers and then select a specific AB series of relay… the newer “CF” type.   

And here we are. The relay part numbers for Allen-Bradley type “CF” relays at 120VAC coil voltage are listed. We pick the “2NO / 2NC” item… two N.O. contacts and two N.C. contacts. Hit “OK” button. 


This brings us back to the Insert/Edit Component dialog. The single catalog lookup assignment task can do much more for us than just link a part number to a symbol for BOM reporting. All of this came in for “free” with just a catalog part number selection.  


Now let’s just take a quick look at how AutoCAD Electrical can use this extra information. 

Starting with the most obvious… the catalog part number assignment enables the relay coil to appropriately list in the various AutoCAD Electrical Bill-of-Material reports. 


But the Manufacturer/Catalog Number selection also auto-annotates the relay coil symbol with the appropriate pin numbers for that relay type. 


And… as we add child relay contacts throughout the schematic drawing set, AutoCAD Electrical will track and apply the next available set of contact pin numbers to each child contact symbol. This is all part of AutoCAD Electrical’s “Pin List” feature. 


And AutoCAD Electrical has our back when we mistakenly try to assign more child contacts than what the parent coil’s part number supports. 


Changing the state of a child relay contact from Normally Open to Normally Closed or vice versa… AutoCAD Electrical will confirm that the parent coil’s part number assignment supports the change and, if so, flips the symbol to the opposite version and applies the correct set of pin numbers. 


The old contact and its set of pin numbers (the left-most contact shown in green here) now becomes available to be used elsewhere in the design – AutoCAD Electrical tracks it all for us, automatically. And, as a bonus, AutoCAD Electrical updates the parent’s cross-reference annotation to now show that the parent relay CR404 now has a child N.C. contact on line reference 406. 


  There it is. A quick overview of the basics of AutoCAD Electrical’s child contact type and pin assignments.




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