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Creating a Homebrew Industrial Process Monitor?
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?"
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.
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 suggestions for implementing and monitoring the monitor systems.
Perps the best place to start is OMEGA.
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: http://www.eissq.com/DialADC.html 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.
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.
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... (and hopefully a profession would know how to avoid having a single point of failure for all the redundancy).
But in this case, it's a simple monitoring thing. The guy wants some values to report to higher ups. The machine has its own controller (can't be screen-scraped), and all that's really happening is just a way to say "valve X is open Y%", without worrying about alarms and crap (presumably the machine has alarms and everything built in). As long as the monitoring won't be doing anything safety critical (it shouldn't interfere with the existing controller), a homebrew solution is perfectly fine.
Heck, a different way is to simply find a way to capture the display output - a camera works. Do it properly and it should be possible to analyze the image and generate the data that way, too.