Nate Holt's Blog

November 20, 2015

Auto mapping “Power” and “Control contact pin assignments in AcadE

Filed under: Electrical — nateholt @ 8:42 am

(this article posted originally on old [lost] blog, March 8, 2007… thanks to Vladimir Panic for sending a saved copy back to me! Here’s the old posting – Nate.)

Here’s the issue. AutoCAD Electrical’s PINLIST contact pin assignments work great when you’re dealing with clean categories of N.O., N.C. and Form-C contacts. But when you might have two types of normally open N.O. contacts on the same parent device, then there is some ambiguity when AutoCAD Electrical auto-assigns pin pairs.


Above is an example of a motor starter relay coil “-K14” with a triple set of “power contacts” on the left and a normal control contact on the right. All contacts are normally open contacts but clearly there is a difference in which ones should be used where in the schematics.

When all the contacts in a group are the same, like a control relay, then it’s no problem. Let AutoCAD Electrical assign the next available N.O. or N.C. or Form-C contact pairing and all is fine.

But, when there are multiple flavors of N.O. contacts like for this motor starter contactor, then the auto-assignment may not give the expected results.

Here are three ways to deal with this situation (where there are two or more types of a given contact type). The first is the out-of-the-box version where you need to manually confirm that the auto-assignment AutoCAD Electrical makes is the appropriate decision (ex: power N.O. versus control N.O.). The second is an enhanced version of this that gives a bit more information – making the decision obvious. The third fully automates the selection of power versus control contact but requires a minor addition to a handful of library symbols.

Let’s look at each of these methods.

Method A: Default pin list mapping – different types of N.O. contacts listed together

This is the current AutoCAD Electrical default. Here’s the PINLIST entry that covers a Siemens part number 3TF511-OAK6 motor starter – 3 power contacts (the L1/T1 through L3/T3 pin-pair entries, each marked with a beginning “1” flag indicating N.O.), 1 normal control contact with pins 13/14 and 1 normally closed (N.C.) control contact (beginning “2” flag indicating N.C.) with pins 21/22.


When you insert the motor starter coil and select this Siemens part number, the above PINLIST value is stored on the motor starter coil symbol. Then, when a N.O. contact is linked to the motor starter, AutoCAD Electrical picks the next available N.O. contact pin pair from this PINLIST string. If the automatic selection is not what you really wanted, you pick the “List” button and manually select the pin pair that is more appropriate. But you have to know which is which. The power and control N.O. contacts are all shown in the same list box and it may not be obvious which is which.


Method B: Descriptions added to the “power” version of the N.O. contacts in the listing

This approach is pretty much the same as above but displays the needed information. Here a “comment” is added to each of the power contact pin entries in the catalog lookup PINLIST entry for this motor starter’s part number. Let’s say that you identify motor power N.O. contacts with a code of “Ma” where “M” is main contactor and “a” means N.O. (and “b” would be N.C.). Here’s the PINLIST entry with the comments added on the three power contacts.


And here is what the “List” dialog looks like when the contact is linked to the parent motor starter coil. Note that the power contact pins are identified in the upper left-hand pick box. The lone “control” N.O. contact is there too but it has no prefix label. So the user can more accurately decide which contact pin pair to choose.


Method C: Best – Auto-mapping of Power contact pins

Here’s the way to totally automate the process, but it requires a bit of setup. First, we modify the entry in the catalog lookup PINLIST for our motor starter coil. We change the first character for each power contact pin pair from a “1” (meaning N.O.) to a “4Ma” meaning special type “Ma”.


Now, the critical step is this… modify the N.O. Power contact library symbol. Add an invisible attribute PINLIST_TYPE with an attribute value of “4Ma”. This is important for this to all work. This attribute will flag AutoCAD Electrical to look for for type “4Ma” pin list entries when the contact is linked to a parent coil symbol.


That’s it. Now, when we pop in this modified N.O. power contact and link it to the motor starter coil, it will access and auto-assign from only contacts that have been marked as type “4Ma”. If you hit the “List” button, this pick list dialog displays. Note that only the three power contacts display.


And here’s the unmodified “normal” N.O. contact symbol. When we link this to the motor starter coil, it skips over the “4Ma” entries and finds the first normal “1” entry.


And if we hit the “List” button, note that only the single N.O. control contact pin pair (pins 13-14) lists (and the 4Ma contacts show up at the bottom in an “other” sublist).


So, there it is. Use this “4x” pin list type to differentiate between different flavors of the same general contact type.


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