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Hello...Need a little advice

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Hello......I just found this forum and thought I'd try to get a little advice. I'm a graduating senior in Automation and Control Engineering Technology and I need to do a senior project. I've got an idea but not sure how to go about it.....well, I think I know how to do it, but I need some help in selecting a PLC for this application. What I'm planning on doing is building a model of one side of a house(a door and two windows). I'm planning on using switches to create a security system for the house. In other words, write a program that when a switch was made, the PLC will send an output to flashing lights and a horn. I'm also gonna tie in a motion light, and fire alarm as well.....but anyway, what I'm needing to know is who makes a cheaper PLC that comes with/or can be programmed with a handheld programmer, since I don't have a laptop and software etc. Anybody have any ideas for a college senior with a wife and kids on a budget as to what route may be best. Thanks

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Hand held programmers are not very popular now but many are programmable by a display that is built into the PLC. The first thing you need to do is count the number of inputs and outputs you will have. Let us know that and the voltage you wish to use on your I/O and we can make some recommendations TW

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To be honest....the application is very simplistic in that an input directly triggers an output pretty much.... Using a small "programmable relay" would be the way to go... The ZEN software from Omron can let you program and simulate the entire system....without the hardware

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Now if you could simulate the windows and doors opening and closing with the software also you might have found our million dollar product

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Now lets make the project interesting ..... cause in it current state if i was t venture over to the dark side i reckon i could teach GI Joe how to by pass the security system by using foil from a stick of chewy (translated as gum) .. The real trick is to work out how to prevent circum navigation of the security system .... In your simple case you could use two feed backs a Normally closed and Normally Open contact,,,,for each window...that way they both must change state at the same time when the window is opend or closed and simple cutting both wires won;t work or will shoting them both.... In the real world say for prisons etc is it a lot more complicated....with a lot more monitoring

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Yep, like guards with rifles.

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LOL Actually, you still use a NO and NC however on each contact you monitor Open/Closed/Open Circuit/Short Circuit, this is all achieved by voltage drop etc On a side note if GI Joe were in da the house with bars would Barbie come and visit...sorry i digress

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How we can get off topic

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OK.........again, I'm trying to graduate this December, and I'm operating on a limited budget......I do not work with nor have ever worked with PLC's, only on a very minimal basis......I have had a couple of programming classes in which I thoroughly enjoyed and I believe that I could do this for a living, given the chance to do it day in and day out......right now I'm an Instrument Technician trying to get an engineering degree so I can better myself. Sleepy Wombat, I'm with you and have thought of that......using two switches per window to keep from beating one.....I was actually planning on using 4 switches per window......the two initial, the first prying open of the window....a switch on the lock, and then another just for good measure.........the door, I was planning on using one on the deadbolt, and another two like the window........also one master switch to implement/kill the system.....and push button acknowledge and a pushbutton test.........also would need one input for a fire alarm. Outputs, I'm looking at sending signals to relays to control horns and lights, and doing a toggle in the program to get the "beep beep beep" and "flash flash flash" effect. The fire alarm, I'm still thinking on that......I'd like to have an alarm and a temperature switch.....the alarm to alert get the horns and lights to flashing to say "hey we've got a problem here"........and a temperature switch to when it realizes that "hey, this house is on fire!! Open the sprinklers" Is this a stupid project? Should I go back to the drawing board?? Any other suggestions to make it interesting?? so I guess I'm looking for something that could handle 10-12 inputs and a couple 3 outputs. I remember the professor talking about a shoebox PLC with a hand held programmer and thought that might be the way to go?? I'm not sure....like I've said, I've worked around this stuff but rarely with it. This may be way "under" some of you all, but I figure on walking before I run. I think it would be a neat project to work on. I may be wrong.

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Sounds like a pretty cool project. At least as good as the classic "traffic light" problem I keep on hearing about :) So you're looking for a cheap PLC. totally understandable. What's your I/O count? If you plan on using 4 inputs per window/door, you're going to quickly exhaust the inputs available on one of the low-end "programmable relay" PLCs. Sure, some of them are expandable, but now its not cheap anymore. And programming from the front display is, umm... Well lets just say not much fun! Here's a thought. I've suggested this before when people have asked about CHEAP control solutions. Get yourself a SLC 150 and programming cable from ebay. The base unit has plenty of I/O and even if you run out, you can add CHEAP expansion units that'll surely satisfy your I/O needs. You shouldn't have much trouble getting everything you need for under $100. The only drawback to this is it's an 80s-era PLC. There's plenty of them out in the field to be sure, but the skills you'll learn won't be quite as marketable as, say, learning on a SLC 500 or ControlLogix. does the school have SLC 500 programminig software you can use? If so, you might choose a fixed-I/O SLC 500. You would still come in under $100 and the time would be a little better spent.

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Take a look at this: http://www.factorymation.net/s.nl/sc.2/category.22/.f I recently switched to these from the PICO, and have been pleased, sligtly more powerful, and a little cheaper. You can download the software for free, and it has built in simulation, the programming cable is less than $30.00, and most of the controllers are under 150.00. You can download the software, and use it to develop your logic for free, if the unit doesn't met your specification, you will know it before you spend any money.

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Another Easy Smart Relay system is the Zelio Logic from telemechanique. http://www.telemecanique.com/en/functions_..._zeliologic.htm It has Free software to download to any PLC and from what I hear is available to download ni PDA format as well if a Hand Held programming system is essential. I Believe a starter kit is relatively cheap coming in at €230 which includes a small smart relay, a programming cable and the software on CD. http://ie.farnell.com/jsp/endecaSearch/par...jsp?SKU=5018882 (Try the US site). The software is pretty intuitive as well and has a nifty Simulation option to trial your program. Also You can program in SFC Mode as well which isn;'t as widespread as I'd thought but isn't much use for your project (I would think). Worth a look regardless.

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Just bear in mind that your time is best spent with a PLC that is common in your industry and your part of the country. If you don't already know the answer to that, your instructors should be able to make good suggestions. Just about every manufacturer makes micro-PLCs these days, you may as well start getting familiar with what your present/future employer will expect you to be proficient with.

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The SLC-500 may be a good option because we have those where I work. I may be able to get my hands on one. I sent my professor a project proposal and he liked the idea, but said that I need to get it more involved. He suggested that when the PLC alarmed that it send a signal to dial my cellphone. How might one go about that?? He also suggested to take a store bought smoke detector and have it send a signal to the plc, which I think I'd be able to handle. Another suggestion he had was to add a keypad to arm and disarm the system. I think I'm going to try to do all three.........I'm gonna get a keypad and use the plc to where I can enable or disable the entire system. Also, I gonna program to where I can enable or disable parts, say I want to enable the fire alarm system, and disable the security system, I can. I think I can get the smoke dectector to work with the plc. The trouble is gonna be to get the system to dial my cellphone when it's in alarm. NOW, where to start?? Edited by Fullback

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If you connect a standard modem up to the com. port, you can program the PLC to send modem commands to the modem and dial a number, if that's all you need. There is an example in the Allen-Bradley download section.

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If ultralow budget is the goal, a microcontroller would be a possible solution as well, they are far less costly than PLCs, however harder to program (standard C/C++ etc) and you have to solder your own circuitboard to use them. Atmel is a big company selling microcontrollers.

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The Problem with using Microcontrollers is that they can often be very difficult to Debug and while the software to program them may be available in freeware versions the only real way top Debug your program is with an Emulator which can be quite expensive. Also you need to purchase a Programming Caddy to Program the chips once you're happy with your program in order to download it onto the chip. If you've all those components at your disposal, then sure, this would be the low budget way to go but if not, depending on how advanced your application is, a Smart Relay, I would believe, would be the best option.

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If you check out the Omron download section i uploaded how to send SMS via a PLC in there some where Another thing to consider is the power suply to the system... should be battery backed so that alarm can't be defeated simply by cutting (turning) off the power supply to the house,,, The key pad thing will require a few more inputs, typically you might have a ten key input with a * and # thrown in for good measure.... generally though there is not a single output for each digit, there might be 4 digital outputs from the keypad which require some outputs to fire the respective channels for the digits etc... when you get more info on the key pad i am sure we can help you out,,,

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You mentioned being able to get ahold of an SLC thru work. Find out from the Maintenance and Enginer folks at work who your AB distributor is and ask about buying or borrowing a 1761-NET-ENI to use with your "borrowed" SLC. It will let you access the SLC from a laptop over Ethernet and the NET-ENI can using an SNMP Mail Server {You'll find several free SNMP Mail Server Programs on the NET} can send text messages to a cell phone and emails as well. Your AB tech Rep can help wiht the details. You might even find your employer wants to implement the ENI and Text Messaging on some critical systems after you prove it in your project.

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