History of the PLC

[Lancie1]

Does anyone remember when the first PLC was sold? I know that "electronic controllers" were available sometime in the 1960's, and the first microporcessor chip was built around 1970, and the first "personal computer" was available in kit form in 1975, but when was the first Programmable Logic Controller made, what brand was it, and how much I/O did it have? I should remember this stuff, but the older I get, the foggier it gets.

 

[rkukl]

I did a quik Google try this link. My understanding is it was Modern controls later Modicon

http://www.barn.org/FILES/historyofplc.html

Rich

 

[Lancie1]

Thanks. I remember some of that now. The first one marketed was the Modicon 084 with 1 to 4K words of memory. Apparently it was sometime after 1/1/1968. Dick Morley "invented" the PLC, and the first one built only had 125 words of memory, was very slow, and was never sold.

 

[Designer]

That made some interesting reading, nice find rkukl

 

[rsdoran]

That is a standard link, I provided it recently here: http://www.plctalk.net/qanda/showpost.php?p=90003&postcount=10Guess it shows the links are not looked at.

 

[Designer]

Sorry, thought it was a recent find, I'm still a newbie to the site

 

[Lancie1]

According to Dick Morley, he started the first PLC in 1968. Apparently The microprocessor was invented sometime before that. I was thinking it was around 1970. Shows what I know (or don't remember since I was alive and kicking at that time).

 

[S7Guy]

Does anyone remember the Siemens PLCs before the S5? I remember working on an old one from around 1979 or so. I swear it was an S3, but I could be wrong. It had a 7-seg on the front, and you could monitor inputs and outputs with it. I don't remember much else.

 

[bernie_carlton]

The original Modicon Dick Morely refers to did not use a monolithic microprocessor (Intel 4004 first produced in 1971). The individual components, memory, arithmetic-logic-units (ALU), buffers etc were all available before that time.

 

[PhilipW]

Dick Morely's group (ex-GM and later Modicon) were the first off the block with the hardware PLC; however Dr Oddo Struger's group out of Allen-Bradley pioneered the ladder logic GUI as we know it, which in terms of software was the equally critical advance that lead to the widespread acceptance of the PLC.

My understanding (and I would love to read from someone who has better details) is that both Modicon and Allen-Bradley introduced commercially viable PLC's around 1970.

The AB product was just called "PLC" which to this day remains an AB trademark, although widespread generic use has probably voided any legal claim. The I/O family was this humungous 4pt/module thing with the Bulletin No of 1774, all run off a parallel port remote I/O arrangement. I have run into a few of these beasts still running although I would think they are thin on the ground now.

Then came the original 1771 I/O with the same parallel network scheme. Soon after was the PLC-2's, then the Mini PLC2,...and so on.

 

[Gerry]

The AB product was just called "PLC" which to this day remains an AB trademark, although widespread generic use has probably voided any legal claim. The I/O family was this humungous 4pt/module thing with the Bulletin No of 1774, all run off a parallel port remote I/O arrangement. I have run into a few of these beasts still running although I would think they are thin on the ground now.

That original PLC (sometimes referred to as PLC-1) was the 1774. It initially had physically huge 16 point I/O (1778) and communicated serially over two twisted pairs. The 4 point stuff you're thinking of was 1777 and was introduced with the PLC-2 (1772).

Prior to the 1774 there was something called a PMC

AB got into the business via acquisition - Information Instruments Inc. in Ann Arbor, and the NC division of Bunker-Ramo in Cleveland (1969-1971). These became the Systems Division in Cleveland. Not all of the staff stayed on - some departed to form ISSC (IPC processors) which was eventually bought by Honeywell.

AB attempted to make a stand on their 'PLC' trademark in the early 1980's - suggesting "programmable controller" as the proper generic term (PC for short). There was brief compliance from companies like Modicon, but, of course, most people associated 'PC' with a different piece of hardware that was bursting onto the scene at the time.