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Hardware Hacking

Creating a Homebrew Industrial Process Monitor? 97

pionzypherm asks: "I work at a glass plant for a major beer company. My job entails monitoring the furnaces that melt the glass. I have been working on a project on the side, collecting data from various sources and compiling it into an easily used form for the higher ups. I've finished two of our three furnaces, but one remains. This furnace uses technology from the early nineties. There is no networking, the hardware is completely closed and unavailable for any screen scraping. Two of the items I'm looking to monitor (and would appear to be the easiest starting point) are two valves for a gas and oxygen line which will provide data on a portion of our energy usage. I was thinking of a microcontroller board or something similar tied in to monitor the positions of the valves. I'm unsure where to begin though. What books, microcontroller boards or alternatives would you recommend for someone new to this? What suggestions would you have for such a project, and what pitfalls might I run into?"
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Creating a Homebrew Industrial Process Monitor?

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  • Open resources (Score:4, Informative)

    by zappepcs ( 820751 ) on Friday May 04, 2007 @02:53PM (#18992729) Journal
    You might try to ask this question on some of the robotics yahoo groups. They are filled with people that do this kind of thing for a hobby and spend a great deal of time thinking about such things not to mention that they do their work with small home brew or cheap microprocessor systems.

    People that make their own CNC machines know a LOT about monitoring position of things etc. This might be your best bet for initial and longer term answers and help about how to accomplish what you wish to do.

    One piece of advice though is think through what you want to ask. When you ask, explain the system in some detail, your thoughts on what might be monitored, how, and what your end goal is with your monitoring. They may have suggestions that go beyond your knowledge scope if you explain more about the system so they can think about the problem with all the requisite information.
    • Re:Open resources (Score:4, Insightful)

      by LWATCDR ( 28044 ) on Friday May 04, 2007 @03:35PM (#18993399) Homepage Journal
      Most home-brew CNC machines are open loop so that tech wouldn't apply to this problem.
      • No, most of them are closed loop. A small percentage of them use stepper motors but most use servos with PID controllers (which is exactly what is inside a process control). Either way, I wouldn't recommend bothering the guys on Yahoo Groups.

        For a working example of a PID controller, try the OpenServo project: [] There are a few revisions to the board, each with a different Atmel chip powering them. The best part is, it's written in WinAVR GCC C/C++.
    • by 40ohms ( 528261 )
      What your describing is not difficult to do, however does mean some PLC related programming. Planning will need to be done. Since it may be critical to the operation of the place I would recommend making plans to simulate the real world field wiring and make things work before actually making the commitment to put that equipment on line. From past experience with many custom control projects I can attest that modifications usually need to be made several times before and after such a project goes on line.
  • Easy (Score:3, Interesting)

    by Anonymous Coward on Friday May 04, 2007 @02:53PM (#18992739)
    If all you need is monitor the position of a valve, you can homebrew the position sensor yourself using a plastic disc, a magic marker, and an LED. The sensor sends pulses as the valve turns, these get picked up by a small microcontroller board. Get an experiment board that supports RS-232 serial. Then, you write some minimal code on the microcontroller to process the events into some reasonable data format, and send them over serial to a PC. Do your real logging and data processing there, instead of on the micro board.
    • Great idea. Another way would be to use a magnetic pickup off of a bicycle speed sensor. Either way, be sure to save your state to flash or something so when power is lost, you dont end up not knowing where your valve is. Steve
    • If all you need is monitor the position of a valve, you can homebrew the position sensor yourself using a plastic disc, a magic marker, and an LED. The sensor sends pulses as the valve turns, these get picked up by a small microcontroller board.

      You could also dismantle a mechanical mouse for this task, or use the sensor from an optical mouse to read the movement of a disc like the one you described in your solution. Another option is to mechanically tie a pot to the valve movement, and read the wiper pos

    • Re: (Score:3, Interesting)

      by Doctor Memory ( 6336 )
      Interesting idea, but it won't monitor the actual position of the valve, just changes in its position. So you won't know if it's closed or not, only if it's more open or more closed than it was the last time it was at rest. Actually, with just a single LED, I'm not sure you could even tell which direction it was moving.

      It's hard to know what to suggest without knowing what form the valve takes. Does it have a round handle, like an outdoor faucet, or a lever, like many natural gas connections have? How m
      • That's what a rotary encoder [] is for.
        • Right, that's what I understood the parent to be suggesting. However, the description only included one LED, which means you can't tell which way the encoder is turning, just that it's moving. If you had access to a decent print shop, you might be able to make an encoder wheel that "faded" from one state to another: e.g., instead of just an opaque block on the track, you'd have a gradient. Then, depending on whether you had an abrupt (clear to opaque) or ramped (clear to translucent to opaque) transition
      • I'm not sure if he is attempting to show when the furnace is on or how much fuel each unit is using and when. I'm not sure a valve position is anything close ot what he want. When turning a valve open or shut, the amount of whatever flows isn't always consistent with the amount the valve it open or shut. In other words, 3/4 open might be letting 5/8 of the maximum flow though.

        Instead, I suggest going with a professional product like a mass flow meter for the gas supply connected before the control valve. Ac []
        • I'm not sure if he is attempting to show when the furnace is on or how much fuel each unit is using and when.

          I got the impression all he was looking for was some way to measure the natural gas and oxygen flows to the furnace, to get an idea (or maybe a better one) of furnace efficiency and to provide some operation cost figures to the bean-counters. He seemed pretty aware that process control was something he didn't want to get in to.

          There are ultrasonic meters that don't require fitting pipes and such.

          That would probably be ideal, as a later response indicated that these furnaces were intended to run continuously until they were EOL'd. That would make fitting an in-line sensor

          • Those links I offered were just the first hit form a google search for "gas volume meter". There are tons of them. The company I bought a air quality analyzer from has shut down but they sold quite a bit of these meters too.

            I'm pretty sure they work for gases as well a liquids. I think the air going in would be forced air and it probably be more efficient to check the air pressure and calculate the size of the ducting asuming it is a forced air intake.

            I'm not in that field either. I used to be in the enviro
    • Is there a visible moving part that you could just take digital images of at intervals and use some visible, machine discernable marking point to calibrate a monitoring program?
    • As other people have said, there are many ways to measure rotation. Optical encoders with absolute position are cheap and easy to interface. If you have to make it yourself, fire up any CAD program, even the cheapest, and draw a big circle -- 30 cm in diameter -- and subdivide it with 360 or 720 or whatever radial lines, then plot it on a laser printer using overhead transparency film. You can get superb resolution. Then read it with an opto pair from an old mouse -- or two opto pairs in quadrature, for
  • by p!ssa ( 660270 ) * on Friday May 04, 2007 @02:54PM (#18992743)
    There are tons of options out there (I havent worked in the field for ~ 10 years). Assuming you can access something to get the readings off you could get a 90-30 PLC to pull the data points. The Cimplicity MMI is a great software package for monitoring, alerting, reporting etc. Try calling GE Fanuc and just tell them what you are trying to do and the can give you plenty of options.
    • p!ssa and some others that posted here have it right. Look into something like Allen Bradley os GE or something. If it is important enough to put a monitor on it, spend a little extra money and do it right. I am a Controls Engineer and have spec'd out stuff like this all of the time. There are cheaper solution, but failure rates of homebrewed methods have too high a chance of failure. Like p!ssa said, call a vendor that sells the stuff, or if you don't have the know how to spec it, call a system integr
      • Re: (Score:3, Insightful)

        by AB3A ( 192265 )
        I'll second what Rogue974 said. I'm a registered control systems engineer. Before you go "monitoring" a furnace you need to consider several things:

        1) Where is your data going? Who might use it and how.

        2) What instrumentation are you going to use and how will it interfere with the process?

        3) What are the safety and reliability issues?

        4) Are there any legal ramifications?

        These systems may be independent for a very good reason. I can't tell you how many data geeks have salivated over the SCADA and plant c
        • by billdar ( 595311 )
          OT, but what defines a "registered" controls system engineer? Is it a US thing, or some state issued title? I only ask because I've never heard it applied before here in California.
          • by Graff ( 532189 )
            Take a look at the ISA CSE License []. There might be other certifications and licenses but the CSE License is a major one for sure.

            (ISA is the Instrument Society of America, CSE is Control Systems Engineers)
          • That's funny, because I think California is the only state the does register control systems engineers. At least, everyone whose resume I've seen it mentioned on always states "Registered control systems engineer in the state of California".
          • by alienw ( 585907 )
            Each state has its own engineering licensing system. But basically, if you offer engineering services directly to the public (as in, working for an engineering firm), you need a license. This mainly applies to civil/architectural/industrial engineering.
          • At last count I think there were something like 38 states that offer Control Systems Engineering as a practice of engineering one can register for. This is basically the ISA's Control Systems Engineer certification.

            For those who are clueless about the whys and wherefores of registration of professional engineers: All states in the US offer tests for which you can become a registered professional engineer. It's basically a way to put your name on the line. You stamp the drawings and documents with a seal
            • by billdar ( 595311 ) *
              Good information, thanks.

              So, if I am understanding correctly, it is a focus or discipline of the PE accreditation. (IE, the whole testing/mentoring process).

  • by fineghal ( 989689 ) on Friday May 04, 2007 @02:57PM (#18992795)
    Are they not willing to fund it/hire someone to do it?
    You might be making this too complicated.
    Let's say you misjudge the tolerances and your fancy little project gets turned into cinders/melts inside the furnace?

    Why can't you monitor the volume of gas flow and then calculate the energy? I assume these gases are stored in a tank or something like that. It should be comparatively easy to attatch some type of flow sensor upstream of the furnace.
    • Re: (Score:3, Insightful)

      by pionzypher ( 886253 )
      This monitor won't be used to control the furnace in any way. There are control systems in place that work as advertised. The issue is that the system is completely closed. Numerous other (and more experienced) entities have attempted to figure out a way to gather the data without success via software. The system itself allows trends with ten minute increments up to 24 hours previous(on screen, no way to get a hard copy besides writing each data point down) This data needs to be collected for the purpos
      • Hrmm ... sounds like it's able to output values to a monitor?

        How about putting a capture unit in between the controller and the monitor?

        That'd allow you to do all kinds of manipulations to the data you get, without altering the controller, and without affecting the direct output to the monitors.

        You'd be working on graphics, but you already know where all the interesting numbers are, so you "simply" do OCR on the interesting parts of the picture. Then dump the numbers into an appropriate database and do your
  • Too easy (Score:1, Informative)

    by Anonymous Coward
    These folk: []

    are in the business of making small microcontroller projects easy, quick and fun. Something like a member of their Basic-stamp family would be pleasantly overkill for your needs. They can convert your temperature readings, valve closures, infra-red readings and such to a time-stamped serial data stream that your computers can collect. There's a large number of good books on how to make the Basic Stamps do all sorts of cool stuff. So if you spend the money there, you'll
    • by ReKleSS ( 749007 )
      I haven't looked at Parallax for a while, but the Atmel chips seem like a better alternative. If you want the convenience of a Stamp, take a look at Arduino []. Open source, based on an Atmel, and fairly cheap.
  • by billdar ( 595311 ) * < y a p> on Friday May 04, 2007 @03:06PM (#18992953) Homepage
    If this is an industrial application, you really don't want to homebrew it.

    Spending the money up front for a reliable, standard solution will save a ton later when your homebrew breaks or some other poor bastard has to support it. There's been too many times I've opened a a panel where my first words are "WTF?".

    Especially if you're working with oxygen. Get yourself a nice little flow meter (micromotion makes a good one). Then you can get both volume, and (presumably) valve position. If the valve is electrically actuated, you can use the information for a host of alarms.

    Either way, if the information is valuable enough to record, its worth the money up front.

    • Re: (Score:2, Insightful)

      by boristdog ( 133725 )
      "If this is an industrial application, you really don't want to homebrew it....if the information is valuable enough to record, its worth the money up front"

      HAHAHAHA! Oh, if you only knew how most factories operate. I work with several leading edge semiconductor fabs and you'd be amazed at the amount of homebrew/seat-of-the-pants solutions abound.

      I am currently working on a system to track production on about $300 MILLION dollars worth of equipment. My equipment budget? I was lucky to get $30,000 and mo
      • by billdar ( 595311 ) *
        I have worked in a ton of factories, and know exactly what you're saying. When a +/- of $0.02 on the shelf is enough for someone to buy the competitors product, I can see why this pressure exists.

        However, I'm sure you've seen factories that are best un-documented and at worst death traps because someone didn't put the $$ or effort up front when doing something.

        Using your example, $30k sucks ass for process data collection. You can do it cheap as hell, say an old dell box with fix32 sending OBDC data to

    • Re: (Score:3, Interesting)

      by tlhIngan ( 30335 )

      If this is an industrial application, you really don't want to homebrew it.

      Well, I thought that way too, until I re-read his requirements. It really depends. If it's automation to control stuff, I'd go with off-the-shelf professional type things. One, there's a lot of CYA - if anything goes wrong, you can blame the hardware, rather than it being your fault (even if it really isn't). Secondly, it's control - things go wrong, and unless there are tons of failsafes and alarms redundantly connected, well... (an

    • by pla ( 258480 )
      If this is an industrial application, you really don't want to homebrew it.

      Depends on why he wants to monitor this machine.

      Working in a similar environment myself, I've found that "management wants to know how often we go out-of-spec" means a whole world of difference from "one mistake will halt production ".

      "Real" hardware to do these tasks, if even available, costs a bundle. The homebrew solution, if just a matter of someone having accidentally uttered a meaningful phrase at a meeting, usually com
  • Use nature (Score:3, Funny)

    by Timesprout ( 579035 ) on Friday May 04, 2007 @03:08PM (#18992977)
    Put a toad in the furnace and then ignite it. If the toad does not jump out then clearly the furnace is not heating quickly enough. For day to day management use a dragon. They are very good with high temperatures and will be able to help out with your energy bills by giving your furnace the odd blast. One safety tip with the dragon though is that if your name is George its probably best not to let the dragon know that.
    • by glwtta ( 532858 )
      For day to day management use a dragon.

      If a whole dragon seems overkill, remember that hypercontiguating two minus-dragons produces 0.6 dragon.
    • Make sure you don't make any sudden moves, or your dragon is likely to explode.

      This is Diskworld, inn't it?
  • Are you trying to monitor energy usage or provide more advance controls to the furnace? For control: first I would find out the specs on those valves (mfg, inputs, outputs) find out if the mfg has a control board and what interface it uses. Otherwise a PLC is one way to go, and usually can you can get i/o that will work in most applications. Start at one piece at a time. An industrial PC could work too. For Energy usage monitoring I would start by sub-metering the furnace's gas and electrical feeds. The
  • by Hijacked Public ( 999535 ) * on Friday May 04, 2007 @03:09PM (#18993009)
    I would suggest asking this same question at [] rather than here.

    If you just want the position of two discrete valves I would suggest finding a used PLC on Ebay. Single box types (like an Allen Bradley SLC 150) that work with discrete IO only can be had for a little bit of nothing. Your biggest concern with costs would be the programming software so I would stick with brands offer it free of charge.

    Without knowing what kind of budgetary firgure you are working with to implement this it is hard to get much more specific.

  • i think the easiest sensor out there is the temperature, start there to learn rol.html []

    and []

    will def help there

  • by Kohath ( 38547 ) on Friday May 04, 2007 @03:11PM (#18993033)
    There are people that do industrial automation. There are large companies that make every type of sensor you can imagine to monitor anything you want. There are industrial controllers to control automatic assembly lines. This stuff is all off-the-shelf. It's not "homebrew".

    If you're asking this on Slashdot, you're looking in the wrong place.

    Do it like a professional would do it. It's a furnace. Stuff can go wrong. Monitoring it with a half-assed homebrew approach is probably worse than simply observing it carefully and worrying about it all the time.

    • by RGRistroph ( 86936 ) <> on Friday May 04, 2007 @03:19PM (#18993153) Homepage
      If all humans were like you, we'd still be hunting with spears, because "hunting is for hunters, doing it with your half-assed bent stick and string that throws a small spear is dangerous."

      Look dumbass, how do you think the "professionals" do it ? They just "homebrew" it and slap some fancy decals on it.
      • Amen, brother! (Score:5, Interesting)

        by pestie ( 141370 ) on Friday May 04, 2007 @05:10PM (#18995081) Homepage
        Every time someone asks Slashdot a question like this, the hysteria crowd comes out of the woodwork to scream about how it's absolutely impossible for an "amateur" to do it, and you absolutely must hire a "professional," lest something tragic happen, ranging from the ever-popular "you'll lose your job!" to a bucket of dead puppies or something.

        Yes, I realize that professionals are sometimes necessary, especially in situations where life is clearly at stake (pilots, medical, law, etc.) I'm sure some jackass will show up to tell me how this is an industrial furnace and that clearly means that a professional is warranted, but we have no idea what the particulars of this situation are. Just stick to the freakin' question, people.

        It used to be the case that "professional" implied not only a degree of competence, but also a certain amount of integrity and experience. But that's just not true any more. All it means now is that someone gets a paycheck for doing something. Often it means that they're experts in nothing more than doing something as cheaply as possible.

        For what it's worth, I'm personally fond of the Atmel AVR [] microcontrollers. Many, many people are also fond of Microchip []'s offerings in the PIC line []. But for rapid development, something like the Parallax BASIC Stamp [] is probably the way to go. They're cheap and easy (like a good woman) and let you focus on the task at hand rather than the bit-level details of how to read sensors, etc.
        • Re:Amen, brother! (Score:5, Insightful)

          by moosesocks ( 264553 ) on Friday May 04, 2007 @07:16PM (#18996693) Homepage
          I feel like you're missing the point here.

          What the original poster is trying to do is not innovative in the least. In fact, it's pretty well-worn territory (which he may have been unaware of by no fault of his own).

          If he had said "I've looked at all of the commerical options, and nothing fits quite right", I'd be in agreement with you that he should go out and try to create his own solution. However, this is not the case, and a lot of time and experience has gone into developing products that fit his needs very well.

          And even at that, there will likely be a good deal of 'hacking' involved in getting these valves to do what he wants them to, given that they're industrial components. Any EE on the planet knows that it's preferable to use a commercially-available IC instead of constructing an equivalent circuit out of components as long as the IC fits the job. The same goes for industrial components.
        • Every time someone asks Slashdot a question like this, the hysteria crowd comes out of the woodwork to scream about how it's absolutely impossible for an "amateur" to do it, and you absolutely must hire a "professional," lest something tragic happen

          I can't speak for other posters, but when I see stories like this I can't help but think "this could be done by an experienced amateur, but if you're posting on slashdot asking how to go about it, you probably aren't an experienced amateur".

          To put it another way,
      • Re: (Score:1, Funny)

        by Anonymous Coward

        If all humans were like you, we'd still be hunting with spears, because "hunting is for hunters, doing it with your half-assed bent stick and string that throws a small spear is dangerous."

        Dear Slashdot:

        OOg want to catch buffalo. OOg never catch buffalo before. OOg only seen buffalo once, from far away. But OOg has good idea to catch buffalo with coconut. Can anyone tell OOg good books to read about coconuts?

        Also, OOg live in North America. OOg only have acorns, and no coconuts. Can anyone tell OOg h

      • by Kohath ( 38547 ) do you think the "professionals" do it...

        They spend the money to buy the pieces of equipment that are designed to do the job. They hook them up the way they are designed to be hooked up. They put fail-safes into the system. It's (somewhat) expensive and time-consuming. It's not a hack.

        It can't really be considered "homebrew" any more than buying a Cisco Router is a "homebrew" routing solution.

        Asking programmers and PC hardware hackers how to do industrial automation is like asking a plumber how t
    • He's not modifying the (potentially dangerous) process, he just wants to monitor data in a way that doesn't involve physical risk.
  • by Steve-o-192.168 ( 1096403 ) on Friday May 04, 2007 @03:11PM (#18993045)
    You should probably install an electronic flow control valve with a flow sensor. Use a microcontroller, PLC, or some such thing to monitor your sensor & control your valve. Monitoring it visually (via camera hooked to an embedded computer) is doable, but way harder than what I just described above. You also run into problems with high temperatures getting to your camera. Take a look at some of the solutions Freescale has to offer. You can order a development board, so you can breadboard something together. Should cost around $200. jsp?nodeId=02430Z [] For a SR Design project for Electrical & Computer engineering, we were tasked to do exactly this with a freescale microcontroller. We needed to precisely monitor the amount of certain gasses put into an oven we use to bake chips. Hardest part about all of this is getting to know the specific PLC or microcontroller you're using. PLC's are easier (generally) to program than most microcontrollers, but not quite as versatile in number/type of interfaces. You need to have a very good understanding of Assembly, C, & how sensors work. You also need to be able to read & understand the mind numbing manuals & technical documents describing the sensors & microcontrollers you choose to use. -Steve
    • You should probably install an electronic flow control valve with a flow sensor. Use a microcontroller, PLC, or some such thing to monitor your sensor & control your valve.

      Installing any kind of inline valve/sensor into a process system almost always requires a shutdown. Shutdowns tend to be very expensive. That's why he wants to do "non-invasive" monitoring and data collection. It may be possible to install valve positioners while the facility is still operating, but be careful.

      There is a way to d
  • by Graff ( 532189 ) on Friday May 04, 2007 @03:19PM (#18993139)
    If you are doing serious industrial work do not attempt to roll your own unless you absolutely have to. The money you save on professional instrumentation will be wasted in downtime and glitches.

    There are plenty of professional solutions out there, from gas flow monitors to automated valve systems to integrated industrial process monitoring and control systems. If you are looking to control fuel and oxygen supplies then you need to get stuff that is blastproof so that a stray spark can't set anything off.

    Start off with a major supplier like Grainger Industrial Supply []. There are tons of components there that might suit your situation. Particularly look at their process monitoring [] section.
  • by Anonymous Coward
    Why don't you use gas flow monitors instead. Most of the modern ones offer rs232 and some even have 10baseT interfaces. These devices are temperature compensated and can be set to match the gas being measured. This would be much more accurate than monitoring the valve position.

    Judging from your question, you sound like a programmer thrust into a hardware problem or a plant engineer thrust into an IT problem. In either case, check with your contacts, suppliers or company engineering group to get suggesti
  • Check out Pic Micro controllers. You can even use something like PicBasic Pro ( to program the PIC's these days. You basically give the chip a regulated power supply (or buy a prototyping board) and use code to work with the IO.

    They even make blank prototyping boards that are already silkscreened for what components to use.

    You'll need a pic programmer (I use this one [], some blank PIC chips (a few dollars each at, and some software to program them in.

    Another approach is to use Paralla
  • by RGRistroph ( 86936 ) <> on Friday May 04, 2007 @03:31PM (#18993343) Homepage
    One technique you might think about, coming from a "first do no harm" strategy to avoid being blamed if something goes wrong with the equipment, is to try to not add new sensors or valves and etc to the equipment, but try to take advantage of the increases in computing power to simply read it and recognize the situation exactly as a human would.

    Check out this project: [] It describes software that uses a webcam pointed at an anologue needle gauge to recognize the position of the needle. Why not, as much as possible, set up passive sensors that don't touch or interact with the equipment in any way, feed them into a cheap multi-gigahertz computer, and process everything that way ? If the furance has a big accident, it would be hard to blame your apparatus.
    • This is brilliant. The philosophy you describe for "first do no harm" by not adding extraneous and intrusive components is actually in use at nuclear plants today. We use closed-circuit TV to watch dials in high dose areas, reducing operator dose, and freeing the operator up to do other things. We don't quite go as far as using an OCR-like process described by the link, since we'd have to qualify that software (which is a buttload of paperwork, honestly, and not worth it), and human eyes are more than go
  • by SixFactor ( 1052912 ) on Friday May 04, 2007 @03:33PM (#18993367) Journal
    ...let's be clear about this: all you're doing is monitoring and gathering data - there is to be no feedback signal from the homebrew rig to control the valves. There's a whole field devoted to control theory, one that is best not trifled with, especially with industrial processes that can potentially cause fatalities.

    If you really want meaningful data from those process streams, you're much better off installing calibratable (calibrable?) flowmeters on those lines that cover the performance range of the process fluids you're working with. If you've got the flow, you don't need the valve position, unless it's for a secondary indication to validate the valve's performance (e.g., position vs. Cv vs. measured flowrate). The flowmeters can be hooked up to provide data for remote collection, or more simply, display data for periodic local reading. Here's a mess [] to start with. Whomever you buy from, you'll need to develop specifications defining the operating range, operating conditions (pressure, temperature, humidity), power requirements, tolerances, calibration frequency, etc.
  • Need sleep (Score:3, Funny)

    by glwtta ( 532858 ) on Friday May 04, 2007 @03:34PM (#18993381) Homepage
    I read that as "Creating a Hebrew Industrial Process Monitor?"

    Really wouldn't know where to begin with that one.
  • Yeah, because if there are two words that go together, it's industrial and homebrew. :D

    There are a whole lot of things that go into handling an industrial system. If you're really going to try to do this on your own, you've got a lot of reading ahead of you; the cost of faults in an industrial system is typically prohibitively high. You're going to need a deep familiarity with modern methods. You're going to need to be familiar with direct hardware control, realtime coding (which is harder than most people think,) constant test polling, and all sorts of stuff most programmers never, ever have to deal with.

    This is not something you can take lightly. If you're going to do this, you have to get it right, the first time, and that means your test cases and regression tests have to be diamond-hard, your specification has to be absolute, and you have to know your timing will not fail. These are difficult issues, but with the appropriate know-how, this can be done.

    Here are some places to start:

    Embedded Control:




  • by spazmonkey ( 920425 ) on Friday May 04, 2007 @03:46PM (#18993565)
    I build CNC and automation equipment, so I can pretty safely say that from what you describe this is a brain-squishingly trivial project. Probably one that can be done over lunch - After you spend five years climbing the learning curve, which is not at all trivial.

        I would just ask someone who does do this for a living out for lunch, it'll take them ten minutes. I do this when I need coding done. The price of a few beers to get the occasional patch or script written is a lot more efficient than many years learning coding to do it myself the one time a year the need comes up.

        The learning curve on automation hardware is at least as steep as learning Linux, and with crappier documentation. Coding guys usually seem to underestimate the complexity of the physical engineering and design side, and think they are always bright enough to just pick it up and do our jobs. There is more to hardware engineering than the butt-crack guy with a monkeywrench, just like there is more to coding than script kiddies.

      In short - unless you want to go into this as a hobby or career change, just treat a hungry engineer to lunch and call it good. Even if you paid him it'd be less than the books you'd need.
  • If there's a way to read a voltage level, you're halfway there. If not, you'll have to build or buy some kind of sensor. There's an open source software package called Argus [] that I use to monitor network devices but I've heard of people using it to monitor various manufacturing functions. It's overkill if you're just wanting to monitor 2 or 3 valves but if you have a lot of them it's a perfect way to do it. It has a web interface and can e-mail you when something changes state.
  • Obtain a 68HC11 microcontroller (they are available for around $30, quantity 1). You will need an RS232 adaptor (figure another 10 bucks).

    Attach a small disk to the valve. Put aluminum foil on one side, and earth the foil. Cut a series of holes around the disk (before attaching the foil, and the disc should be a non-conductive material). Put a sensing whisker so that the whisker is in contact with the foil, or disc. Now when the valve turns, the microcontroller will get pulses.

    Of course, this doesn't tell y
  • I looks like you're trying to measure the flow of natural gas and oxygen by measuring valve position. While it is possible to do, you would need to be able to calibrate the position to flow rate, this would also require very consistent supply pressures and back pressure. On top of that the flow is not likely to be linear with valve position. I've worked with valve positionners that can do this but you'll need to do some redesigning of your control system to integrate them, for that you'll need an expert.

  • Monitoring gas and oxygen supplies and all the hardware that controls it can be dangerous. What if your homebrew micro-controller with its connection wires makes an earth-loop and noise gets on the signal control lines?

    What is your fail-safe strategy? Do the valves fail open or closed if something short circuits in your setup? Does your home-grade micro controller survive the heat & vibration of the environment?

    Buy something of the shelve from a "standard" industrial automation firm. You can get anythin
  • I have a solution for you that will work. I thought I might give it to you for free (as in beer) but decided I would rather exchange it for beer (as in free). But, I only drink microbrews (being an Oregon beer snob)... so I guess you're out of luck.
    • *snort* There are about 10,000 different microbrews made in Oregon, and 9,982 of them are IPAs. Good luck if you're looking for a decent porter or pils...
      • Naturally there are breweries that only sell their beer on-tap that have good porters, but you have to come to Oregon to find them!

        For those that are bottled, I would have to say that you need to give the following a try: Monkey Face Porter from Cascade Lakes Brewing and Mocha Porter from Rogue. Second place are Black Butte Porter from Deschutes Brewery (which has suffered in quality as it has gotten bigger, IMHO) and offerings from McMenamins.

        I don't know why you'd want to drink a pils from any brewery (
  • Are you trying to extract flow information from non-instrumented valves? If so, you need to either replace the valve with something modern that outputs its data cleanly, or just insert flowmeters in series with the values to be monitored. Either way, get something clean and professional, don't do a DIY job that's hard to maintain. Also, once you have an instrumented device, I'd not recommend putting a homebrew micro-controller system on a factory flow, especially a glass factory, which abounds in abrasive
  • There's standard hardware for this sort of thing. You can get little industrial I/O units with Ethernet interfaces. [] They're little boxes with an Ethernet connector on one side, and digital, analog, or thermocouple inputs on the other side. They're built to hold up in a factory floor environment, and easily replaced if damaged. You can even get wireless ones. []

    If you're going to send signals around a plant, 100baseT is actually quite noise-resistant. More so than TTL signals or even RS-232, because it'

  • You can not go wrong with Allen-Bradley PLC systems. Find a large Allen-Bradley vendor (Rexel-Nelson is a good one) and use them as a resource.

    Have them send a representative out to you and help tell you what product line will fit you best. That's what vendors are for.

    If there is a possibility of becoming one of your suppliers, any good vendor will bend over backwards when you need help like this.
  • If you want to reply offline using the email address above we can refer you to an industrial monitoring systems specialist who does work for, among other companies, Corning Glass.
  • Have you looked at all the data acquisition stuff National Instruments sells? They ought to have something that will work, although it will pretty much have to be PC-based. Definitely beats the hell out of trying to homebrew this, though. I'd say that if you have to ask, it'll be too much work -- microcontroller projects have a way of taking way more time than they should.
  • Why use home brew you could do it with a PLC of almost any brand(most likely AB or Omron) over an Ethernet network that way you could automate the whole plant and remote monitor from home. If you go with AB you can use the DF1 protocol to read the information directly off the PLC it's not difficult at all. I just graduated from college and my senior project was similar to this with some other fancy stuff such as QC and a nice HMI and SCADA system. I say for 25k you could automate your plant and control prod
  • So you're trying to use a "homebrew" solution at a major beer company? Isn't that like dividing by zero or something?

    (note to morons: this is a joke)

Marvelous! The super-user's going to boot me! What a finely tuned response to the situation!