Anyone heard of a Bulletin 1750 PLC?

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I thought I was pretty familiar with the various PLC offerings A-B has had over the years. I figured there was the "original" 1774 PLC, then the PLC-2, PLC-3, PLC-4(cough, cough), PLC-5, The SLCs, and all of the newer stuff. So I just happened to be running off some copies of the old 1761-MMB Micro Mentor book for the maintenance crew, and something caught my attention on the third page. After lots of squinting, I read "Bulletin 1750 PMC Programmable Controller" on the nameplate of a PLC system I'm SURE I've never seen, in the picture. I checked the A-B site, didn't find a thing. Googled it, and found several part numbers in surplus companies listings, so I know it is more than a figment of my imagination. So what's the scoop on this thing? Have any of you seen these in the field? Does it pre-date the 1774 PLC?

[Gerry 13]

I've never seen one, but have heard of them. Yes, they pre-date the 1774 - don't know by how much. There was reference to them on the old 1770-SA tape decks.

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Found another reference to it here: (see page 26) http://www.ab.com/abjournal/nov2002/pdfs/ABJ0211.pdf And apparently THIS wasn't even A-B's first PLC offering.. Something called the "PDQ II" was mentioned, as something A-B developed based on a DEC minicomputer, but ultimately did not bring to market.

[Timotheos 0]

Hi guys, Check out this link too which has a pretty cool timeline of AB PLCs. http://www.rockwellautomation.com/ab100yea...LC_25_Years.pdf Does it look like the picture on this page? I'd love to see the picture you have. I've been doing some research on PLC history. The PDQ II and PMC were Allen Bradley's first attempts that really didn't take off. The Modicon 084 was "the PLC" at the time. Later in 1974 ABs Bulletin 1774 PLC laid the groundwork for their success. The patent is actually online at http://www.freepatentsonline.com/3942158.pdf Tim

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That PDF was pretty cool! Found ot some things I didn't know before from the timeline. I believe the picture I found in the MicroMentor book is of the same system that is shown under "1970" on the timeline. The timeline pic looks like it might be just an I/O rack without the controller.. the one in the book shows what looks like a control unit mounted above the I/O rack in a cabinet. Unfortunately I don't have the book picture scanned.. I could scan it if you'd like, but I fear it wouldn't turn out too good because its so small :(