Reader Feedback: What the L?

A Reader Reflects on Our Articles 'PLC Genesis', 'The History of the PLC' and 'History of Control; History of PLC and DCS'
Aug. 16, 2012

Nice article from Jeremy Pollard ("PLC Genesis," June 2012). But my (possibly defective) memory recalls that originally Allen-Bradley called the device a PC for "programmable controller." Then IBM usurped the acronym, requiring the insertion of the "L."

Dick Morley's reminiscences initially refer to the Modicon 084 as a "programmable controller" ("The History of the PLC"). And I found one history that confirms my memory, but with Google I could probably find something to confirm anything ("History of Control; History of PLC and DCS").

Carl Henning,
deputy director,
PI North America, www.us.profibus.com

Pollard's fuzzy recollection: The very first piece of PLC literature I had my hands on was for a PMC (programmable matrix controller), which AB licensed from III (I think). The early 1970s is when the PLC arrived, and Odo Struger trademarked the acronym. I wouldn't disagree that the hardware was first referred to as a PC, but I believe it was changed for 'logical' reasons…no pun intended. The PC from IBM in 1981 was clearly after the PLC. That's my story, and I'm sticking to it!

About the Author

Carl Henning

Carl Henning

Sign up for Control Design eNews