Over 50 years ago I started working in automation. Some things have changed since then.

Then I sat at a drafting board with a universal arm drafting machine. I drew relay ladder logic on D-sized vellum. (I still have my drafting set – compass, inking supplies, etc. and my drafting pencils.) The relay logic was implemented using physical relays; there were no PLCs, DCSs, or PCs back then. Implementing the controls for plastic extruders involved temperature control of heating/cooling zones along the barrel and heating zones in the dies. The temperature controllers were basically millivolt meters with jeweled movements calibrated for Type J thermocouple inputs. Calculations were made with a slide rule. (I still have that too.)


Some interesting projects in those early years:

A plastics extruder in a hazardous environment

It was extruding a plastic tube to constrain the pattern of shot in a shotgun shell. I used explosion proof enclosures with many, many bolts to close and mineral insulated power cable. Interesting, but very expensive. There was a second extruder for a later but similar project, but this time the extruder was installed in a purged room and extruded through the wall. This was much more economical. I blogged about this last year, PROFINET in Process. It was a contrast between then and now.

Dewatering extruder for solid rocket propellant

Because I was a computer geek way back then (the early ‘70s) I wrote a computer program to design the feedscrew that moved the material through the extruder barrel. The design was so complicated, they couldn’t figure out how to make it on the brand-new computer controlled lathe. So, I wrote another computer program to design the tooling needed to make it on a manual lathe. The computer was a time-shared IBM 360 which I accessed via acoustic modem.


Progress was made on the temperature controllers – they went electronic. Now in addition to Proportional control, we had Integral and Derivative also – PID. And they got a lot smaller. Later projects saw me implementing PID temperature controllers in PLCs.

I implemented PID controllers in PLCs while working for a Systems Integrator. It was also time to start using networks, albeit proprietary networks like DH+ and TIWAY. Direct wiring and proprietary networks are ancient technologies now. Open networks like PROFINET are the present and the future.

The best job I’ve had though is the one I’m now leaving – educating engineers, maintenance staff, and the occasional IT professional about PROFINET. Yes, I’m past retirement age. Blogging, Tweeting, YouTubing, Facebooking, PROFINEWS-ing, and teaching classes in person – these methods of communicating have been, dare I say it, fun!

Blogging has allowed me to educate, provide early news, report on trade show visits and more. The “more” is to express my opinion about technology and occasionally go off-topic. You can see those off-topic posts here.

Those off-topic posts include my PROFIblog farewell, The Next Chapter.

Not sure what I’m talking about when I say plastic extruder? See the video in the PROFIblog post Long, Long Ago in the Land of pi Tapes.

A little more retrospective at Five Decades in Automation.

Although this article has been a look back, I’m looking forward… to travel, sightseeing, visiting friends, kids, and all 12 grandkids. I’ll be taking pictures and starting a travel blog. But this is my final issue of PROFINEWS. I’ve finished Tweeting and all the other social media too as of August 31. I’m retired. Farewell. It’s been fun.

— Carl Henning