Home automation using a PC as controller

[Toni Ross]

hi der!

what is the difference between a solid-state relay and an electromagnetic relay?

[webmaster]

The relay is an automatic control element whose output variable undergoes a change by leaps and bounds when its input variable (electric, magnetic, sound, light, heat) reaches a set point. A typical relay is a remotely controlled operated switch; it consists of one or more contact pairs that serve to open, close or transfer external circuits. The relay is just a switch, activated by electricity. A relay is a simple electromechanical switch made up of an electromagnet and a set of contacts.

Idea in the simple electromechanical relay operation is that the relay output contacts are normally open, typically a spring keeps them in this position. When you wnat to close the relay, you feed current to the control coil. The current at that coil creates a magnetic field that moves the output switch mechanical contacts to physically different position, to such position that the output contacts close the output circuit.


Solid state relays (SSR) are the electronic equivalents of a mechanical relay with some notable advantages. Solid State Relays (SSR) is a relay w put and output whose functions are achieved by means of electronic components without the use of moving parts as found in Electromechanical relays. Solid state relay (SSR) and semiconductor relay are both names of relay like device which works like a normal relay. A basic definition of a totally solid state relay is a device that operates a load circuit without the use of physical contacts. This relay contains a transistor or triac which turns on a load circuit. An SSR is a semiconductor device that can be used in place of a mechanical relay to switch electricity to a load in many applications. Solid-state relays are purely electronic, normally composed of a low current control side (equivalent to the coil on an electromechanical relay) and a high-current load side (equivalent to the contact on a conventional relay). Advantages of SSRs are quieter operation, longer life and faster repetitive operations, especially where counting or numerical operations are concerned. SSRs are also more immunite to physical shock than electro-mecahnical relays (EMRs). Disadvantages are cost and higher currents may require external heat sink components. A typical SSR consists of an LED input, which is galvanically isolatedfrom an output switch circuit.

[Tomi Engdahl]

I was browsing around the web and found this link that looks interresting

Very Simple Control Protocol
http://www.vscp.org/
A free/open protocol for automation and control

This site is dedicated to the VSCP protocol, a very simple and free protocol for SOHO automation tasks & friends. The protocol is so easy that everyone can grasp the idea behind it in a few minutes. Therefore it's also very easy to construct and use VSCP aware modules and components. Nodes just start up and then serve the control solution reliable and stable for ever and ever and ever.....

The protocol is free and is not designed to conquer the world and every Small Office and HOme. It is constructed just because its fun to make tiny little things work together.

VSCP was initially designed to be used on CAN, Controller area network. The project therefore maintains an open source can-driver for Linux and Windows.

[toni ross]

well my professor is asking me of what type of switche shall i use on my project...
type os switch?? d u know them??

[Tomi Engdahl]

Please define what you are planning to o with the switch on your project then we can propably give you tips for right switch type to use.

[jprampolla]

Hi Tomi and Folks,

Well, I promised that I would post the results of my project where I used solenoids to depress keys on a
Windows keyboard, and I have put it all in a page on my site:
http://yourpage.blazenet.net/jprampolla/sounds.html I use it for sounds effects on my toy train layout. I would
be happy to explain in more detail, but most of you are actually more knowledgeable than I am with
electronics. The beauty of the project is in using an embedded media player in html, so if you know html a
little, it is very powerful and yet simple, too.

Thanks to all of you who have helped with my electrical questions.

Take care, Joe.

[Tomi Engdahl]

If you want to interface your device to PC USB port, Velleman has a kit for this K8055. There are details of this kit at
http://www.velleman.be/common/product.a ... &id=351346

The K8055 interface board has 5 digital input channels and 8 digital output channels. In addition, there are two analogue inputs and two analogue outputs with 8 bit resolution. The number of inputs/outputs can be further expanded by connecting more (up to a maximum of four) cards to the PC's USB connectors. All communication routines are contained in a Dynamic Link Library (DLL). You may write custom Windows (98SE, 2000, Me, XP) applications in Delphi, Visual Basic, C++ Builder or any other 32-bit Windows application development tool that supports calls to a DLL.
The price of the kit is around 40 Euros / Dollars.





For Linux users there seems to be an open source project to make Linux drivers for this kit at http://linuxk8055.free.fr/

They sell the kit also as ready made module with code VM110
http://www.velleman.be/common/product.A ... &id=351980
And they also sell quite nice looking 8 relay module MV129 that can be conencted to VM110 (DIN rail mountable with sutiable Velleman case)
http://www.velleman.be/common/product.A ... &id=361120

[Hometoys]

Interresting reading:

Automation in the digital home
http://www.hometoys.com/wrap.php4?/htin ... breton.htm

Phase 1 – Install Dedicated Home Automation Server for Voice Activated & Dynamically Scheduled Lighting Control

Phase 2 of the automation projects was to add UPB control devices to allow voice-activated and web-based control of the various subsystems around the home

[Tomi Engdahl]

The parallel port controlling through document parallel port controllign through web part has been expanded at
http://www.epanorama.net/circuits/paral ... webcontrol

A new "Web controlling using PHP and AJAX" part has been added.
The software is based on PHP software running on Linux server and a JavaScript based client application running on the user web browser.



The software (parallel poer imitated with file) is available for test at
http://www.epanorama.net/circuits/portc ... olfile.php

[toni ross]

hi there!

can you give me informations about the 25 pin parallel port

-structure
-how to program
-etc..


and also programming a parallel port using visual basic

thanks!

[Tomi Engdahl]

The information on parallel port programming you are looking for can be found at
http://www.epanorama.net/circuits/parallel_output.html

That document should have pretty much all information you want, except that Visual Basic source code. There are links to some other web pages that give Visual Basic examples.

[HWman]

Some interresting project links:

Computer Christmas
http://computerchristmas.com/index.phtm ... istmas.com

The site was designed to give the community of Christmas light enthusiasts (especially computer controlled lights) an all-in-one site for anything we can imagine.

[Tomi Engdahl]

For home automation I browsed around and saw a quite interresting looking kit:

Velleman K8056
http://www.velleman.be/common/product.A ... &id=351282



This relay card can be used in several ways : stand alone card, addressed by switches or open collector outputs or remote controlled through RS232.
It has eight relay outputs (5A 230V AC).
It uses quite simple looking ASCII based control protocol that consists of simple few character ASCII strings sent to RS-232 port at 2400 bps speed (2400N-8-1 settings). Manual includes instructions of the commands to use to control. This kit is claimed to come with grpahical Windows control software. Web page http://vesta.homelinux.free.fr/dotclear ... ous-linux/
has some Linux control software for this kit.
Looks very interresting for any home automation application.


Velleman seems to be also selling a box for this kit with code K8006
http://www.velleman.be/common/product.A ... &id=341587


(in this picture there seems to be some other kit inside the case, but you get the idea). I think this kit on this case would look more like this:

[Toni]

is it more easier to use Visual Basic as a software in controlling appliance using a PC than C language?

[Tomi Engdahl]

What is easier to use Visual Basic or C depends on what you are actually trying to do and what language you know better.

Visual Basic is what I have seen pretty good for building application with graphical user interfaces quite easily. The downside is that you can't do everyhting easily with Visual Basic. There are many cases where you need to do some thigns for example with drivers written in C language, and that is just liked as DLL to the Visual Basic program.

With C language you can do pretty much everyhting if you know how to do that. Writing the program is usually somewhat more time consuming than using Visual Basic. Especially building nice raphical user interfaces to C program is pretty hard (it can be done but is is harder than with Visual Basic).

So in controlling applications I would expect that in many case you would need both Visual Basic and C languages, if those are your languages of choise. But the low level controlling routines with C (it is where C is good) and then build the actual user interface with Visual Basic (it is good for building graphical user interfaces easily).

If you need tools that can be used to build graphical user interfaces that work on many platforms, then consider building the higher layer user interface part of your control application using one of those programming tools: TCL/TK, Python, Java