PLC and attatching a machine to computer (IMPORTANT)

Hello everyone, I have a couple of queries.
1) First is PLC , PLC stands for Power Line Careers. This phenomena is actually all about stuffing everything on electricity cables that carries power for ordinary households and other items. I have heard that it is already implemented in United States, UK and Canada that those ordianry aluminum electricity cables(or Power Line Career Cables) not only carry electricity for ordinary household items but also broad internet bandwidth, cable channels and some other services as well. This could bea great idea as it can reduce number of cables flying across the city. I tried to "GOOGLE" the term "PLC" but didnt find something helpful, I would really appreciate if someone could help me in this stuff or put up some links.

2) Thank you for procedding to my second query. My second query is how to communicate with a hardware machine using a computer. Like what if i want to switch on and off a 100 watt bulb using my computer or turning on and off a fan by sending some signal over wires from my computer. Or making it a little more complex, what if i want to turn on a machine's power using my computer, I would really appreciate someone putting up a tutorial or a link.
Thank you for reading my queries.
I would thank you all in advance.
Ommy

You should probably look into industrial control cards

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PLC stands for Power Line Careers.

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Heh, just wanted to point out that to me (and probably alot of others)...PLC is a programmable logic controller, something that you could maybe use with #2. rcgreen is correct in saying you need some industrical control cards, there are alot of vendors out there and programming them is oooohhhhhh so fun (not). At the university where I used to use these things, they always order them from National Instruments, but I wouldn't be suprised if there are better things out there...

/nebulus

I've had fun progging them..
Simple logic usualy works realy well on plc's

(the kind nebulus was talking bout)

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I've had fun progging them..

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The ones we had were on a serial interface, so I had to program for that, and they were somewhat complicated in that they controlled temperature and had to be able to exactly alter the temperature or keep in constant, with only a +- 1 degree Farenheit difference allowable. Dunno, having to wade through all those bytecodes and stuff was sickly fun, but also caused many headaches for me...hmmm...maybe now that I think about it, maybe the temperature controls were what were the pain...I don't remember anymore, just remember constantly grumbling about the things...

Maybe it was fun in a demented, self-inflicted painful kind of way :)


/nebulus

Power Line Carrier is a term that is used to describe the power distrubution equipment like meters, etc. Someone coined the phrase Power Line Communications a few years ago, when labs started testing the concept of distributing data over power lines. You can imagine the issues accociated with that! I have been following it off and on for a few years and I think it's to the point that Wi-FI was 3 years ago and cable was 5 years ago. It's exciting, since everyone has power delivered to their houses.

The US is not using it outside of very limited test areas. There are a couple of test points that have been successful. Here are some quick references I found...

http://www.wired.com/news/technology...,57605,00.html

http://www.nwfusion.com/news/2003/06...cialfocus.html

http://telephonyonline.com/ar/teleco...udy_broadband/

http://www.pcworld.com/news/article/0,aid,110390,00.asp

Some old school electronic enthusiasts might also see Printed Logic Circuit from older trace boards when they see PLC. :)

As for programming computers to turn on off things. X10 is Great.

It connects to power lines in your house and uses a simple language to address devices. You plug and X10 module into the power outlet or bulb socket controlling the bulb, set it's address and then the computer can turn it off and on by sending a signal to the address. Of course you need the Software and a card in your PC too. Most of X10s commands are available to make your own software. You can also buy remotes and cotnrol stations that will do it. X10 is CHEAP and runs over your power lines. There are also 220v versions available for Europe.

www.x10.com
www.smarthome.com
http://www.antionline.com/showthread...&highlight=x10

Turning off power can be done via Outlet strips that can be controlled via Rs232 (serial with a modem) or TCP/IP. You connect to the outlet and turn off and on ports via a control panel or command line interface

www.blackbox.com

Well nebulus200, Thanx for your reply. I know about the programmable logocal controller. Roadclosed gave me quite a good piece of information on query no. 1. That was great. Gave me alots of information. Query 2 about controlling a relay board using parallel port is still not satisfied. Anyone who can be more precise in using any language and and tellling me what phenomena is actually involve would be a great help. x10's wont ork anymore. I want to program one of my own.
Thank you
Road closed waiting for your next post.
ommy

Turning of a physical object, like a light bulb (on or off) requires two things: an actuator, to open and close the physical electricity path, and a signal to initiate the actuator. This is like a relay with a state, either normally open or normally closed. If you wish to power cycle a computer you would want the relay in a normally close state so power is always running to the box. Then initiate an open signal to the relay. Normally this is a voltage that energizes the relay magnet and pulls the circuit arm in some direction. If the status is normally closed the application of energizer voltage will open the relay, shutting off power to the box. It will stay in this state until the energizer voltage is removed and the relay is reset to a normally closed state. So now you have to run a circuit, connect a power supply etc. to manipulate the actuator or relay. X10 devices handle the signaling "in band" meaning on the power circuit so extra wires and connections aren't necessary. Why won't X10 work..??. it's a standard language that can be manipulated as far as I can tell, and it's cheap. You can get the language off the internet and build your own app.?? X10 is a simple rudimentary language.

This thing could get quite complicated if you want to build a system yourself. I wouldn't do anything via parallel port. R2-232 and R2-422 on a serial connection are easier or as stated, get a card with various voltage outputs and tie those to a relay and then tie your device to the relay.

Another option is to build an app to monitor the serial port and when it sees a certain ASCII combo, the application could initiate a windows or Linux shutdown. But you are not physically removing the power in this case.


//EDIT trying to find some real world example. This guy wrote a program to control lights over a web page!!! http://www.x10.crevier.org/webinterface/

http://sourceforge.net/projects/wish *This linux project has caught my interest.