Serial Port Interfacing?

Question

I Currently Have my house Automated using a LPT port on an old laptop. i have 12 outputs (d0-d7 and c0-c3) and 5 inputs (S3-S7). However i want to be able to add more and more devices. I want to make a Relay Board (similar to this http://www.ebay.com/itm/like/180872906009?lpid=82) Using The Usb Or the RS232 Serial port. I found the Shield for The RS232 (http://www.ebay.com/itm/like/150835793421?lpid=82) but i don't know how to use it. I know i Need some sort of TTL Decoder but i don't know what i need.

I could care less if it had inputs but i want to control Relays to Automate More of my house ex. turn lights on/off. i will be making a program to interface with the relays under voice command.

Any help would be appreciated.

P.S. i Have The Programming skill to use Either port.

Please provide links if possible

Answer 1

Ask the seller with the relay board if he will give you the control codes and baud rate. Or, you could build your own relay board and make up your own serial control codes for a micro controller like the Arduino Uno. The Arduino can also use the built in USB if you want, then you don't need the TTL to serial adapter for it. The Arduino has 11 digital pins (besides the serial pins) you could use for relay driving, plus the 6 analog pins that can be made to be digital outputs as well. You could get more ports with the Arduino Mega 2560 with It has 54 digital input/output pins.

Answer 2

We have got RS232 as well as USB based Relay & DAQ boards. You can operate these boards with simple programs using VB or C# or Delphi or any higher language program that can talk to Serial port.



Specially U452 USB based Relay & DAQ card is very useful for Home Automation needs as not only it has got Relays on board but also has up to 16 Digital I/Os and up to 8 Analog inputs. These can be not only be utilized to connect with Switches & various sensors but also can be used to connect more relays if the need arises.



For RS232 & USB based relay boards please visit - http://shoppee.iknowvations.in/index.php?main_page=index&cPath=8



For User Manuals of these boards -please visit http://iknowvations.in/downloads/



Hope this may help you. If you have any questions you can send technical query also, which will be answered by support team.

Answer 3

RS232 only addresses one receiver, whereas USB can have many.



Buy the board, cheaper than designing it yourself. And much faster, I'd say it would take months and thousands of dollars to do it yourself.



USB interface is complicated, read the spec. You can get ICs that do the interfacing, but you have to study the ICs to determine how to connect and program them.