Happy new year! Stay connected


Coming up in connectCAD 2016

Coming up in connectCAD 2016:
Cable Paths extend beyond schematics to the physical world:where the cables go in a building,what are the specific locations of wallboxes/cable drop points & the paths between them.You’ll be able to make your own customised Devise Placement Tools that can insert into circuits, eg, if you’re designing RF distribution systems you can create your own handy tools for splitters / taps etc. using duplicates of Insert Device each set up to place a custom device symbol..

Read more

Knowing where to tap…

from Mark Buckton – absolutely brilliant!

A Giant Ship Engine Failed.
The Ship’s Owners Tried One Expert After Another, But None Of Them Could Figure Out How To Fix The Engine.

Then They Brought In An Old Man Who Had Been Fixing Ships
Since He Was A Young Man.
He Carried A Large Bag Of Tools With Him, And When He Arrived,
He Immediately Went To Work. He Inspected The Engine Very Carefully,
Top To Bottom.

Two Of The Ship’s Owners Were There, Watching This Man,
Hoping He Would Know What To Do.
After Looking Things Over, The Old Man Reached Into His Bag And
Pulled Out A Small Hammer. He Gently Tapped Something.
Instantly, The Engine Lurched Into Life. He Carefully Put His Hammer Away.
The Engine Was Fixed!

A Week Later, The Owners Received A Bill From The Old Man For Ten
Thousand Dollars.

“What?!” The Owners Exclaimed. “He Hardly Did Anything!”
So They Wrote The Old Man A Note Saying, “Please Send Us An Itemized Bill.”

The Man Sent A Bill That Read:
=====================
Tapping With A Hammer……. …….. …….. $ 2.00
Knowing Where To Tap……… …….. ……… $ 9,998.00
====================================

Labelling conventions and human nature

Labelling when you think about it is what keeps the world organised. And in our crazy little world with all its wires and connectors without some kind of labelling system we would soon lose our way.

The completely arbitrary nature of labelling makes it a special challenge for a CAD developer. We’d love to provide you with super-automated tools for this, but no matter what road we take someone will tell us it’s wrong, or agree with us but not be willing to change their habits.

Take patch panels for example. Some people label them like this:

A 01 02 03 04 … 21 22 23 24
B 01 02 03 04 … 21 22 23 24

C 01 02 03 04 … 21 22 23 24
D 01 02 03 04 … 21 22 23 24

So the top row of a panel has one letter, the bottom row has the next letter and the patch points are numbered across.

Others like it this way: each panel gets a letter to designate it and the patch points are numbered left-to-right then top-to-bottom.

A 01 02 03 04 … 21 22 23 24
A 25 26 27 28 … 45 46 47 48

B 01 02 03 04 … 21 22 23 24
B 25 26 27 28 … 45 46 47 48

The snag here is if there aren’t enough connectors you can’t easily change the patch panel size in mid-design. A good workaround for this is to label panels as though they were 50-way regardless of actual size:

A 01 02 03 04 … 21 22 23 24 (25) (26)
A 51 52 53 54 … 71 72 73 74 (75) (76)

That let’s you easily extend your panels to 26-way or 32-way without having to re-work everything, and makes efficient use of the available namespace. That’s quite smart. And if I had to pick one this would probably be it.

Most people agree you should skip the letters I and O because they can be confused with the numbers 1 and 0. But guess what? there are some folks in the world who didn’t do that and now they’re stuck with the system they have.

Others like to use numbers throughout and add a prefix to show if it’s a video or audio patch panel like this:

V01 01 02 03 04 … 21 22 23 24
V02 01 02 03 04 … 21 22 23 24

V03 01 02 03 04 … 21 22 23 24
V04 01 02 03 04 … 21 22 23 24

And many variations on these themes exist.

And then we move on to location-based naming. Great idea but very hard on the designer. Think about it… In order to know what equipment you have to mount in racks, you will probably have to finish the schematic designs first, right? So you do the rack layout and then go back and label your patch panels! and guess what happens if you have to modify the schematic???

By now you’re probably beginning to see how the simple business of writing a patch panel tool becomes a nightmare of complexity.

The problem with labelling conventions is that people are very attached to their own way of doing things. And with some justification because who wants to go back and re-label everything?

But there’s another psychological dimension to it. The more arbitrary and fundamentally insignificant the decision the more emotionally invested people become in it. A well-known cognitive bias known as “bike-shedding” or Parkinsons Law of Triviality. In labelling there is no absolute truth so you can fight to the death over it and NEVER, NEVER BE WRONG!