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    #21
    Re: Getting into PLCs

    Nothing is ever worth trying to get working, not even to learn. In fact nobody except experts are allowed to learn anything new. Anyone who has no background should ever work on anything they are interested in because it's a waste of time.

    Sorry if this sounds sarcastic because this was supposed to be a humorous remark to a debbie downer.

    Comment


      #22
      Re: Getting into PLCs

      I did not like the extra safety procedures, having to ask workers to close valves and shut off things.
      There is a Safe Work Permit and formal procedure in a plant to prevent disasters, as well as Lockout Tags so nobody just flips a breaker on.

      It's hard to learn in a plant environment because a pump or switch on when it should be off, is trouble.
      Here, you can shut off the pump/valve circuit breakers so the PLC does not do anything harmful. In a water treatment plant there is less risk.

      The pump motor looks wired as Wye (star) because there are two Neutral wires leaving the terminal block. It's just one speed.

      Comment


        #23
        Re: Getting into PLCs

        Originally posted by Dannyx View Post
        Of course, there's a lot of work to be done there and anybody, even if they're a completely random bystander could tell you this even after a superficial look at these sites.

        I'm sure that when the producers of designed them, these filters were properly thought out. It goes beyond our jurisdiction somehow to try and figure out the mechanical/chemical side of things, like if the sieves or whatever were not meant for such a high volume, or they chose improper sites for their install where the soil is unstable and drops down into the filter bath or whatever, stuff like this. We only care about the control.
        You're not (apparently) tasked with replumbing the system. But, I suspect the customer wants more than just to have things "up and running again" -- with the expectation that they will be down, again, RSN!

        Process control systems are very different beasts than self-contained electronic devices. They're almost all "different" from each other. You can draw up a plant diagram that covers a myriad of different instances of that plant, yet each can have different characteristics that cause the controls for one to be miserably inadequate for any of the other instances.

        One advantage to PLCs (to justify their cost) is that you can easily adapt them to changes in the physical plant as you learn from the shortcomings of your previous implementation.

        E.g., simply (physically!) relocating a sensor can change the performance of the system (by eliminating lag or more tightly coupling the sensor to the sensed variable). For example, locating the temperature sensor close to the heat/cool source is one way of getting LOUSY performance from most systems.

        When a PLC-based control system is deployed, the customer is usually provided with sufficient documentation to maintain AND MODIFY said system as he learns what its shortcomings are. WITHOUT having to scrap everything and start anew.

        If your customer isn't sophisticated enough to know what's wrong with the current implementation, then the best service you can provide to him is an analysis of the problems of the current system and a proposal for how to minimize them, going forward (with various price point options). You don't make changes just for the sake of making changes (or, because you are more comfortable with a particular technology)

        You're in the enviable position of SEEING the consequences of the previous implementation (the folks who originally designed it DIDN'T have that opportunity because they hadn't deployed it, yet). If all you do is repeat the previous mistakes... <shrug>

        I've had several clients, over the years, tell me that they awarded a contract to me because I worked with their existing implementation -- instead of scrapping it (as the other folks bidding on the jobs had proposed). It demonstrated my understanding of their CURRENT problems as well as an appreciation for the ($$) investment they had already made in a (inadequate) solution.

        Solving a problem that you don't understand is just folly.
        Last edited by Curious.George; 11-24-2018, 03:06 PM.

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          #24
          Re: Getting into PLCs

          Originally posted by redwire View Post
          It's hard to learn in a plant environment because a pump or switch on when it should be off, is trouble.
          It's also a lot higher "pressure/stress" environment. You're often tying up a very expensive set of equipment and/or impacting "production" (which translates to $$). And, often you're dealing with mechanisms -- that can be sizeable and do considerable damage in a fraction of a second! ("Hey, what's all that red liquid on the floor, over there? And, where's Bob???")

          In some industries, the act of taking a system out of service (so you can tinker with it) carries high startup costs when you reintroduce it to service, later.

          For example, have you changed anything that can affect the quality or reliability of the "output"? Or, the safety of the staff who will be exposed to it? Does any of this have to be recertified/revalidated? How "visible" will your tinkering now be to The Organization?

          In the medical/pharmaceutical fields, you NEVER want to tinker with production equipment out of fear that you'll render it "useless" (until revalidation) -- even if your proposed changes/improvements are never adopted!

          Comment


            #25
            Re: Getting into PLCs

            Originally posted by MixMasta View Post
            This is some kind of shitty Chinese PLC. Based on everything you have said here on this forum thread and your background my advice to you would be not to waste your time and the customers time. Move on.

            Sorry if this sounds blunt.
            You don't know the client or the (proposed) contractor -- or what the criteria are for each of their decisions, in this process.

            The contractor may be "hungry" and willing to undertake something (even at a reduced rate) that he wouldn't otherwise. The client may be fed up with The Experts -- who've left him with this "mess".

            Also, don't underestimate the value of a fresh (even naive!) set of eyes looking at a problem. Sometimes they can see things that are too obvious for an expert to notice! I spend a fair amount of time explaining highly technical problems to lay folks (investing effort in devising a way of bringing it to their particular level of comprehension) solely for their "naive" insights. Even if they don't find an answer, they often help you question your assumptions about a problem (they don't have the same sort of preconceived notions that YOU do!)

            "Why are you doing... ? Why can't you ...?"

            "Hmmm, now that you mention it..."

            Comment


              #26
              Re: Getting into PLCs

              Originally posted by Curious.George View Post
              If your customer isn't sophisticated enough to know what's wrong with the current implementation, then the best service you can provide to him is an analysis of the problems of the current system and a proposal for how to minimize them, going forward (with various price point options). You don't make changes just for the sake of making changes (or, because you are more comfortable with a particular technology)
              Correct: they don't know/don't WANT to know about the technical side - they just want sh!t to work so they won't get busted (again ) for reporting fake favorable results for water tests, when in reality the vats were filled with sh!t and the pumps were not operating This worked until a higher authority decided to send some of its own men down there to collect samples for analysis and, as you'd expect, that's when the excrement hit the air circulation system so they decided that rather than living with it and facing the horrors of more fines and possible lawsuits for feeding contaminated water into the canal, they'd reach out for help...that's all backstory.

              Also correct: not starting from scratch, that's for sure, hence why I started digging into this particular XD PLC, otherwise I would've suggested something Siemens........for the sole reason that I saw comprehensive vids about them on Youtube....of course that's only kidding as there's no way you'd call yourself "professional" that way Still, behind the humorous nature of the above statement, the essence is that sometimes you just have to go where there's more documentation and resources available (not the case here, since it's not possible - we're pushing on with what's already there).

              O.T: Take laptop repairs for example (something which I've been struggling to become familiar with lately): if I'm going to buy a dead laptop from an auction site with the intent of fixing it to sell it, the first thing I do before I even ask for a final price is hop on google and see if I can find any resources on it. Being stuck without a schematic or boardview is a miserable experience (the latter is a rare luxury in fact!). The way I see it, it may not necessarily mean you're not "professional" because you're relying on schematics....Louis said this himself multiple times: "I'm not a genius and have no idea where stuff is on the board or what it does just by magically placing a finger on the board *BAM* there's your problem". If no resources are available, I'd rather not risk it.
              Wattevah...

              Comment


                #27
                Re: Getting into PLCs

                Originally posted by Dannyx View Post
                Correct: they don't know/don't WANT to know about the technical side - they just want sh!t to work so they won't get busted (again ) for reporting fake favorable results for water tests, when in reality the vats were filled with sh!t and the pumps were not operating This worked until a higher authority decided to send some of its own men down there to collect samples for analysis and, as you'd expect, that's when the excrement hit the air circulation system so they decided that rather than living with it and facing the horrors of more fines and possible lawsuits for feeding contaminated water into the canal, they'd reach out for help...that's all backstory.
                Hence the value of being able to say to the client: "We believe the following problems contributed to the failures you've seen.... Thus, our suggestion to make the following changes to the implementation to mitigate these problems."

                When you ask them to spend more money (including your salaries) just to get back to where they already are, its a tougher sell than asking them to spend a bit MORE than that to get to a better position. The first $N of that larger amount they rationalize they will need to spend, regardless. So, the "fix" is only costing them the difference above that $N instead of the full amount.

                Also correct: not starting from scratch, that's for sure, hence why I started digging into this particular XD PLC, otherwise I would've suggested something Siemens........for the sole reason that I saw comprehensive vids about them on Youtube....of course that's only kidding as there's no way you'd call yourself "professional" that way Still, behind the humorous nature of the above statement, the essence is that sometimes you just have to go where there's more documentation and resources available (not the case here, since it's not possible - we're pushing on with what's already there).
                I still contend your best effort is to explore the details of the "problem space" instead of the "solution space". A better understanding of the problem will also help you understand why the particular solution may have been adopted. As well as the shortcomings that the solution brings with it.

                Comment


                  #28
                  Re: Getting into PLCs

                  Originally posted by Curious.George View Post
                  I still contend your best effort is to explore the details of the "problem space" instead of the "solution space". A better understanding of the problem will also help you understand why the particular solution may have been adopted. As well as the shortcomings that the solution brings with it.
                  This to me is very important to understand if going to come with a workable solution to what ever the problem may be
                  9 PC LCD Monitor
                  6 LCD Flat Screen TV
                  30 Desk Top Switching Power Supply
                  10 Battery Charger Switching Power Supply for Power Tool
                  6 18v Lithium Battery Power Boards for Tool Battery Packs
                  1 XBox 360 Switching Power Supply and M Board
                  25 Servo Drives 220/460 3 Phase
                  6 De-soldering Station Switching Power Supply 1 Power Supply
                  1 Dell Mother Board
                  15 Computer Power Supply
                  1 HP Printer Supply & Control Board * lighting finished it *


                  These two repairs where found with a ESR meter...> Temp at 50*F then at 90*F the ESR reading more than 10%

                  1 Over Head Crane Current Sensing Board ( VFD Failure Five Years Later )
                  2 Hem Saw Computer Stack Board

                  All of these had CAPs POOF
                  All of the mosfet that are taken out by bad caps

                  Comment


                    #29
                    Re: Getting into PLCs

                    Originally posted by sam_sam_sam View Post
                    This to me is very important to understand if going to come with a workable solution to what ever the problem may be
                    Until you figure out what you're trying to accomplish, any effort you make down a path towards an imagined solution is just wasted effort.

                    I was tasked with "updating" a gaming device (i.e., gambling) some years ago. It was only after I sorted out how it SHOULD work that I started looking into the implementation -- with an eye towards how I could add features and improve performance.

                    Because I had taken the time to research how the "winner" SHOULD be selected (and how the odds affecting that selection could be adjusted -- at the Operator's discretion), I was able to determine that the game was paying out on certain wagers far more often than it should have!

                    No idea if Customers (Players) had discovered this (the Law of Large Numbers suggests "no") but it was obviously a flaw that shouldn't be allowed to persist in the implementation as, "on average", it was costing the Operators for it to be present.

                    And, it motivated me to pay particular attention to all of the "math" for other, similar faults.

                    You do a lot at establishing your own personal "cred" when you can point to problems that you discovered by having a good "process".

                    Comment


                      #30
                      Re: Getting into PLCs

                      Missed this. Part of my job is working with PLCs (new projects engineer for a Tier 1 Toyota supplier). Mostly Mitsubishi PLCs (old and new), some with Pro-Face HMIs.

                      My suggestion for beginners (if you don't know if PLCs are the solution) is the automation direct Click series of PLC... they're very cheap (freeware software!) but reasonably powerful (and can be used with the C-more series of HMI's if you want). Compared to the $$$$ "name brand" PLCs are (even the low end ones!), they're a low cost way to get one's feet wet (and what I did 75% of my PLC ladder programming on in college).

                      https://www.automationdirect.com/adc...le_micro_brick)
                      sigpic

                      (Insert witty quote here)

                      Comment


                        #31
                        Re: Getting into PLCs

                        Ok guys, believe it or not, after almost a year, this PLC project was rebooted: Big Boss obtained the much sought-after maintenance contract for these water treatment systems I wrote about in the first post, so I was once again appointed the unofficial automation "engineer" for them, with my job being to inspect the PLCs and related electronic components and ensure they function as they should, as well as to analyze their working principle in detail and decipher all their functions.
                        Somewhere in the last week, we managed to visit all of the filter stations covered by this contract, which are scattered around the county in several key points along the canal, and we pulled the control boxes housing the PLC and contactor out of two of them which upon first glance appeared totally dead. Thankfully, out of the 11-12 total stations listed in the contract, only 3 or 4 are "smart" ones and have some form of automation, while the rest are "dumb" ones, manually controlled by a couple of MCBs in place of a PLC - no electronics whatsoever.
                        We brought the two PLCs and keypads back to the shop to clean them and work on them, which is the only way it could be done, because when dealing with a lot of unknowns like this, the only sensible way to work is in a shop, on the bench, with a reasonable amount of tools and equipment readily available, because if you're literally out in the middle of nowhere under the hot blazing sun with only a laptop trying to diagnose some random piece of equipment you've NEVER seen before that's sat outside for the past 4-5 years and appears dead, you'd have quite an unpleasant challenge on your hands...anyway.

                        Short-ish version so as not to bore the more eager of you how might not be willing to read through my walls of text before getting to the actual issues I've encountered, so: I was not able to connect to the PLCs using a CH341 USB to Serial adapter, neither with a PL2303 adapter. I had hoped it would be a simple matter of connecting the TX/RX pins correctly between the two and the "XCP PRO" software would connect to the PLC just as it would via an on-board COM port, but it didn't, even after hours of trying. While the COM port corresponding to the serial adapter did show up as COM X in XCP PRO, it couldn't connect to the PLC and Putty showed no activity either. The same held true for the other adapter, which has an actual DB9 connector at the end. The only way I was finally able to connect to it was by connecting it to the onboard COM port directly and only then did XCP Pro managed to connect.....all seemed fine and dandy except there was one huge issue which put a stop to the whole show: the PLC is locked with a password Fail....so that was that. It's currently on hold till we either manage to get hold of this password somehow, which is borderline impossible after all these years since these have been deployed and have gone out of warranty, or program a new PLC from scratch, "blindly", based on our own ideas of how it should work based only on what we can see on the functional one. What could be causing this ? Are there various "types" of RS-232 ? The only difference I can see is the different voltage levels: an on-board COM port can swing anywhere between -10v and +10v, whereas an USB adapter cannot do that. It can only go as high as 5v/3.3v...

                        More details:
                        Both PLCs power on and do something, when I say "do something" I mean there's some LEDs that come on to indicate the status of the relay outputs and the external contactor clacks on/off at seemingly random intervals. One of the keypads is dead and powers on with only the backlight and a blank display, while the other is fine. When hooked up to the PLC with the serial data cable we also extracted from the site, THIS is what showed up. Obviously some parameters pertaining to the water down in those tanks I talked about, like the current operation being "nitrification" (maybe mixing some compound with the water), some countdown and other stuff. It's all academical really, because all I care about at this point is the PLC system working - the chemistry and physics behind it all is of no concern to me, plus we weren't provided with any in-depth documentation anyway, so we have no way of determining what all those values represent or what they should be. Pressing the UP and DOWN arrow keys on the keypad cycles through a few more screens with even more stats, mostly counters like how many times the wells have been purged and then refilled, how many minutes the air bubbler was on, etc. how much time has elapsed since the last cycle and so on (again, not interesting at this stage). One screen in particular though was very useful in working out at least some of the details of this system, since it allows you to actually send various commands to the outputs by pressing certain buttons on the numeric keypad on the right which turn on/off corresponding outputs. What should happen at the other end of these outputs is still unknown - maybe there's some valves/solenoids/pumps that come on but we won't know for sure until we put it all back together and see what happens in the field....that's it for now. Will keep you posted.
                        Attached Files
                        Wattevah...

                        Comment


                          #32
                          Re: Getting into PLCs

                          open it then
                          maybe it uses seperate memory and you can recover the password & stuff.

                          Comment


                            #33
                            Re: Getting into PLCs

                            Makes sense from a logical perspective, but even I find some familiar memory IC inside, which is unlikely but never mind, it's even more unlikely to find something "unlocked" to write back to it, unless maybe I copy it from an identical PLC. Our supplies department or whoever is in charge has already ordered a couple of replacement and backup PLCs and keypads for this project. It's a tall order, since with no way to pull the code from the original ones, it's going to be a long and tedious process to create my own version from scratch, like I said in my last post. It's doable, but takes a heck of a long time. The only thing that comes remotely close to hacking into the existing ones is physically removing whatever IC MIGHT store the pass key ("MIGHT" being the key word here) from a new PLC which comes unlocked from the factory, copy that and then plop it onto the locked ones, which is a bit of a rabbit hole since there are a lot of unknowns here, like what this IC is, whether or not it's readable by any of the common programmers like the CH341, or whether it lives through this whole operation and I don't end up killing the brand new PLC as well, which might be an expensive lesson.

                            As a curiosity, I did briefly remove the top cover on one of them because there's some thin wires coming out of one of the vent holes on the side of the PLC which go to a seemingly random male DB9 port on the front of plastic box that houses the PLC, MCB and contactor (see below). I could kinda suss out what these were for just by looking, but I wanted to take a peek inside nonetheless: in order to steer clear of the less common 9-pin mini DIN connector normally used to program these PLCs (hidden away under a plastic flap on the left), whoever installed them initially opened them up and ran these wires straight onto the board onto the solder points of the DIN connector to adapt to a more easily accessible and common "outboard" DB9 serial port. The construction of the PLC is pretty modular from what I could briefly see in there: the boards are stacked and interconnected with male-female headers rather than flex cables, which makes putting back together less of a hassle and less risky, though I didn't dig too deep into it to see what memory it might use and IF it's doable at all, though the idea sounds tempting nonetheless. There were plenty of chips in there, but who knows how or where the password is stored. The make and model are not a common thing to come across either, so there's little to no resources whatsoever. The only resources are pretty badly translated manuals for the PLCs and XCP Pro software, but that's about it....

                            The keypads are the worse part by far: the software used to program them is not the same that's used for the PLCs (called "XCP Pro") and after taking a brief look at it, it doesn't appear to have an option to download existing code from a keypad after you upload it, so I'll have to improvise my own to sort-of do the same things as the functional ones. The same as with an Arduino, it's "ready only" after you upload code to it, or at least I think so....
                            Attached Files
                            Wattevah...

                            Comment


                              #34
                              Re: Getting into PLCs

                              Did you try the default password to get into the plc (six zeros)

                              Comment


                                #35
                                Re: Getting into PLCs

                                Hmmmm. I did try a couple of common default passwords, but I wasn't sure A) what length the password even has or B)what the default password is for this particular case. I can't remember if I specifically tried six zeroes, but now that you mention it, I'll try it again just to rule it out.
                                There's also a confusing menu going on on the keypad itself: if you hit the "right" arrow key on the keypad (connected to the PLC of course), it takes you to a screen where you've got "Open password" and "Close password". That sounds pretty confusing to me, as I'm not sure what exactly "opens" and "closes" here. Selecting "open password" takes you to another screen which requires you to actually input an 8-character password. The default is 8 zeroes, but upon hitting "set", it just says invalid password, so I'm not sure what that does or if it's related to the programming password XPC Pro asks for. The "close password" option does something else but can't remember for the life of me what - it just displays a message like "password closed. Press ESC to exit" and that's it. Initially I thought this locks/unlocks the keypad so you can't alter those commands, but it doesn't - the panel is always unlocked and I doubt this has anything to do with the software anyway.....
                                It actually makes sense for the previous company who installed these to set passwords and I was kinda expecting to hit a snag like this, though I kept some hope in the bottom of my heart. It makes sense to make the lives of subsequent contractors like us miserable and as hard as possible, though when handing over a project like this, IMO, it should be mandatory, by contract if anything, to also provide full unrestricted access to all of the systems which are now outside your control and ownership...in other words, don't troll those who come after you >_>
                                Wattevah...

                                Comment


                                  #36
                                  Re: Getting into PLCs

                                  The password I was refering to is for the connecting with the PLC using XCP software, It's password length is 6 charactors
                                  Attached Files
                                  Last edited by R_J; 09-12-2019, 11:39 AM.

                                  Comment


                                    #37
                                    Re: Getting into PLCs

                                    From what I saw by playing with the software, there's two places where you can type a password: in the menu you're showing which apparently SETS the password, but also there's a message box which pops out whenever you hit "download program from PLC", which you can't see because you haven't got the actual hardware. Without it, it refuses to download anything.

                                    There's also the matter of that "secret upload" option. Reading through the manual, as far as I could make out, it's some sort of "write-once" option, possibly separate from the whole password deal entirely, so it's like the ultimate lockdown feature which prevents any subsequent operations on that particular PLC....the broken English makes it quite difficult to understand.
                                    Wattevah...

                                    Comment


                                      #38
                                      Re: Getting into PLCs

                                      I see the broken English is hard to understand also. I just thought if you tried to upload the software from the plc to the pc, it is possible they left the default password, I'm not sure about the decryption setting
                                      I see there is also a password for the op series display, These will likely be different.
                                      Last edited by R_J; 09-12-2019, 12:32 PM.

                                      Comment


                                        #39
                                        Re: Getting into PLCs

                                        still waiting for the board shots - i'm genuinly curious whats in these.

                                        Comment


                                          #40
                                          Re: Getting into PLCs

                                          Originally posted by stj View Post
                                          still waiting for the board shots - i'm genuinly curious whats in these.
                                          Will do.

                                          That's right: the display unit ITSELF may be password protected, though there's no way to retrieve the programming from it anyway, so it's not too critical ATM. The PLC is the business end.
                                          Wattevah...

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