This post is part of The Guide to Building Management Technologies.
What are setpoints?
Many years ago, my good friend Ken Sinclair, editor of AutomatedBuildings.com wrote a commentary called "Building Automation has become pointless".
The observation Ken made was that the controls industry can no longer even define what a "setpoint" really is. As open standards penetrate our industry, "What's the point?"... of even trying to continue to segment out "point counts".
Nowadays, a point could still be described as a traditional 1000 ohm platinum device that varies in resistance as the temperature fluctuates, but it could also well be a snippet of .XML retrieved from a web services query! The delivery of data a physicality of a "point" complicate things enough; but it really starts getting interesting when Enterprise Facility Management systems incorporate data sources from outside the HVAC/control system.
But first, what's the origin of the term "point" when referring to inputs and outputs on an automation system? Well, here's how the story was told to me:
Several years ago, I asked my good friend, Roger R. Henderson (who since, has passed on - RIP Roger), "Roger, why did people start calling points, .... points?"
Roger was a pioneer in the controls industry. He worked for early 35 years for Honeywell. He was directly involved in the old Delta 1000 and 2000 system projects.
As we insiders know, the first electronic networks run inside a facility where for the Building Control and Fire Life-Safety systems. Probably the only other comparable network at the tie would have been for the Telco system (which some of the early BCS's shared!).
Many times, even in the late 80's, as a technician for Honeywell, I would unpack an IBM PC and people would gather around it marveling at the "new" Personal Computer. Often, the control system front-end was one of the first PC's people had ever seen.
These early systems were segmented by "Channels" (or main "trunks"), "Groups" (or "Controllers") and finally endpoint devices and I/O (input/output). So.... if you wanted to know the general health of a BAS, you would punch in the address of the first point available, on the main Operator's Terminal, which was:
Channel #1, Group #1, and Input #1.
On an old Delta 2000 CPU, these address parameters were separated by decimal points, meaning that every site had at least a point "one-oh-one-oh-one" or more correctly, one-point-oh-one-point-oh-one (1.01.01). The way Roger told the story, "Legend has it that the decimal point separation (and designation) wound its way up into the nomenclature of our industry, that's why points are called 'points'" (1.1.1).
Think of it as an early Internet IP address, with only three digits!
I'm sure that there are similar tales at other companies, and if so, I guess we can put this one right up thre with the "who invented the thermostat" debate (of course, everybody knows that Al Butz at Honeywell did that! ;)).
Now we know what a point used to be, our next part will be what the point is now - click here for What's the Point Part 2.
Posts in this series
Top 3 Benefits of Benchmarking for Facilities Management
What Facility Managers Need To Know About Smart Buildings
Are You Managing Your Energy Spend?
4 Common Myths of Energy Conservation in Building Management
Precision Building Management: Understanding Closed Loop Control