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AB PLCs? Anyone know good books?

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  • AB PLCs? Anyone know good books?

    At work we use AB PLCs almost exclusively in the infrastructure process equipment. Micrologix 1000 and SLC 500. I have a basic understanding of ladder logic but the AB system is a little more complicated than some. Anyone know of any good books to get me started on the AB flavor of ladder?

  • #2
    Gag! Ladder logic is so... 70's

    Rockwell has some old Micrologix tutorials here, under "Programmable Controllers":

    http://literature.rockwellautomation..._category.hcst
    "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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    • #3
      Have a look at www.thelearningpit.com and www.plcs.net - there's some good general info + tutorials on these sites; not rockwell specific but may be useful...

      Cheers
      Batt

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      • #4
        Ladder Logic is still perfectly fine for many applications. You do not need many of the bells and whistles you see on modern "machine controllers." We have two identical "sheeters" in production -- except for the controller.

        S1 has a simple text-on-background display, all the prompts on one screen, and you navigate with arrows and keypad. It has yet to fail since 1989 when we built it.

        S2 is identical frame and mechanically, same servo, same sensors... 2009 vintage touch-screen with full motion video, 256 colors, animated interacts, sound effects and I assume if it ever worked properly the same sort of outputs as S1.

        S1 can be edited with a simple program on my laptop. S2 you have to take modules out, take them to engineering and hope the programmer is free. S2 is down more than it is up because of PLC faults.


        Simple is better in my opinion.

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        • #5
          Originally posted by lazlo View Post
          Gag! Ladder logic is so... 70's
          Yabut, the learning curve is pretty shallow. I would rather have a third shift technician troubleshooting ladder logic than getting me out of bed to come in to divine the intentions of the hotshot designer who used the latest-and-greatest whizbang.

          That being said, I wish I could do more systems in ladder logic. Instead, I am pretty fast and cheap turning out small test fixtures that use dedicated micros similar to the Arduino, and program in (sorry, Laslo) Basic. The cheap is what gets me in trouble, as management doesn't want to spend the money on a PLC, but still wants a sophisticated test. As a result, nobody else works on them and they land back in my lap.

          <edit to add>
          Ladder logic ain't what it used to be. Just starting up the more recent AB programming software is nearly beyond me now and I have been left hoplessly in the technological dust. I have to get help from the technician to get to the ladder logic.
          Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
          ~Practitioner of the Electromechanical Arts~

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          • #6
            Programmable Controllers Using the Allen Bradley SLC-500 family by David Geller

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            • #7
              The biggest pain with the MicroLogix and SLC500 platforms is the addressing of data structures. Not nearly as intuitive as the newer Compact and ControlLogix systems. I've seen some pretty impressive applications done on these platforms though. I might still have some of my training material and have some contacts in Tech support. If you have some specific questions, PM me and I'll see what I can do to help. I've been doing mainly ControlLogix Motion control for the last few years but I might be able to help. Most of the manuals are available online and I think there isn't any access restriction. I can get to everything through the internal network, but I googled and it looks like the following link will get you to all the manuals.
              http://literature.rockwellautomation..._category.hcst
              Look under the Programmable Controllers directory.

              Greg

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              • #8
                When I got into AB's I dropped by the local AB rep and he gave me the programming manuals, if you do not have these already?
                They show example programming.
                Max.

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                • #9
                  Originally posted by Weston Bye View Post
                  Yabut, the learning curve is pretty shallow. I would rather have a third shift technician troubleshooting ladder logic than getting me out of bed to come in to divine the intentions of the hotshot designer who used the latest-and-greatest whizbang.
                  Agree Wes, but Ladder Logic is literally programming with mechanical relays. The "latest-and-greatest whizbang" is the C programming language

                  The irony is that most of those PLC's are embedded x86 PC's running a ladder logic interpreter. You can flash and run C or C++ on it, and be programming with a modern procedural language in minutes.
                  "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                  • #10
                    Originally posted by lazlo View Post
                    Agree Wes, but Ladder Logic is literally programming with mechanical relays. The "latest-and-greatest whizbang" is the C programming language

                    The irony is that most of those PLC's are embedded x86 PC's running a ladder logic interpreter. You can flash and run C or C++ on it, and be programming with a modern procedural language in minutes.
                    Are you going to ask the shop floor electrician to trouble shoot in C ??
                    At least if he can pull up a ladder diagram to monitor with, to him it represents the old paper print that he used to trouble shoot an assembly line problem, the added advantage of course is the STATUS can be monitored on line.
                    In any case, just about all PLC's now can be programmed in Boolean, but ladder display, and as to speed, controlling the relatively slow out-board components, high speed Dsp processing is not really required.
                    Max.
                    Last edited by MaxHeadRoom; 03-12-2013, 12:49 PM.

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                    • #11
                      Indeed, but even if I knew a "modern procedural language", I would still be surrounded by Ladder Logic Luddites who have no interest in "improving" themselves. For that matter, at my advancing age with retirement less than 1000 days in the future, I question the return on the effort investment needed to "improve" myself.

                      This is not to say that I don't recognize the benefits of the higher-level programming languages, as attested to in my previous post, but the "pictorial" nature of ladder logic makes it easy to quickly grasp and follow for troubleshooting by the repair guy who may not be a "programmer".

                      <edit> Max beat me to it and said it just as well.
                      Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                      ~Practitioner of the Electromechanical Arts~

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                      • #12
                        Originally posted by MaxHeadRoom View Post
                        Are you going to ask the shop floor electrician to trouble shoot in C ??
                        Fair enough!

                        Originally posted by Weston Bye View Post
                        This is not to say that I don't recognize the benefits of the higher-level programming languages, as attested to in my previous post, but the "pictorial" nature of ladder logic makes it easy to quickly grasp and follow for troubleshooting by the repair guy who may not be a "programmer".
                        It depends on the complexity of what you're trying to control. If you're programming a bar feeder, or some linear or state-machine flow of industrial equipment, then sure. But if you have a more complex process to control, loops and subroutines in ladder logic are crude and artificial.

                        People often program PID loops in ladder logic, for example, that's constructing a mnemonic memory circuit using stone knives and bearskins
                        Last edited by lazlo; 03-12-2013, 12:54 PM.
                        "Twenty years from now you will be more disappointed by the things that you didn't do than by the ones you did."

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                        • #13
                          Originally posted by lazlo View Post
                          ... But if you have a more complex process to control, loops and subroutines in ladder logic are crude and artificial.

                          People often program PID loops in ladder logic, for example, that's constructing a mnemonic memory circuit using stone knives and bearskins
                          Most of the modern PLCs have dedicated instructions for doing these things in a rather streamlined manner. It's still clunky by the standards you work to, but not nearly as bad as you think.

                          Speaking of relay logic, back when I was self employed, my dad, who was a construction equipment operator had a slack period with no work. I showed him how to build and wire relay panels for me, following the D-sized blueprints I drew.

                          Construction work picked up for him and he went into an Oldsmobile plant in Lansing to do some demolition to make way for a new assembly line. He was working next to an existing assembly line that was having some trouble with a relay panel. Engineers and electricians looked in the panel, looked at the prints, watched the line as the car bodies came along and hesitated at one point, and scratched their heads. If they physically pushed the body a little farther on, it would continue along. After watching for a while, Dad wandered over and looked where they had been pointing at the print, then went over to the relay that the print referenced and saw two wires fallen loose from a terminal. He reached in and tucked the wires back into the terminal and the problem was solved. Then came the questions: "Who the Hell are you?" & etc....
                          Weston Bye - Author, The Mechatronist column, Digital Machinist magazine
                          ~Practitioner of the Electromechanical Arts~

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                          • #14
                            Originally posted by lazlo View Post

                            People often program PID loops in ladder logic, for example,
                            I doubt very much if the word 'Often' applies considering that just about all PLC manuf. offer sophisticated modules now, in fact 20yrs ago I retro-fitted a single axis CNC boring machine with an early AB PLC/servo module.
                            No good for interpolated motion, but worked for this application.
                            I think a lot of todays thinking is 'If it is Right, We can Always Change it!'
                            Max.

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                            • #15
                              Originally posted by Weston Bye View Post
                              ...with retirement less than 1000 days in the future...
                              But who's countin'
                              Milton

                              "Accuracy is the sum total of your compensating mistakes."

                              "The thing I hate about an argument is that it always interrupts a discussion." G. K. Chesterton

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