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?"
Open resources (Score:4, Informative)
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.
Look into GE Fanuc or Allen Bradly (Score:3, Informative)
Too easy (Score:1, Informative)
http://www.parallax.com/ [parallax.com]
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 be building a working system from cookbook instructions.
With externally actuated valves my favorite sensor is the hall-effect sensor (available at the site above). It's corrosion resistant, doesn't wear and is not angle sensitive. You glue the cute little magnet where it will fit, and the sensor where it will be close to the magnet in the on-position and Viola!
When you want a low cost solution, and to make thousands of them it's hard to beat the Atmel ATtiny series of microcontrollers for low power/cost and high reliability.
Don't want to be done on the cheap (Score:4, Informative)
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.
Not asking Slashdot... (Score:3, Informative)
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.
Industrial automation is a business (Score:4, Informative)
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.
Suggested way to do this (Score:3, Informative)
In Industry Avoid Homebrew If Possible (Score:3, Informative)
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 [grainger.com]. There are tons of components there that might suit your situation. Particularly look at their process monitoring [grainger.com] section.
Homebrew industrial tool control, eh? (Score:3, Informative)
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:
Realtime:
Integration:
Testing: