I need to build an On off Switch. I have an LCD projector mounted in the ceiling and I want to build a device that will turn it on at a given time of the day. The switch must have a serial prot and store and send RS 232 control codes. From looking at this device the Arduino I am sure it can do it but I need a little help getting started.
Do you know how to turn on the projector with a switch? Its pretty easy once you know that. If you can just kill power to it, and return power to it without needing to press any other buttons, I would recommend something like: https://www.sparkfun.com/products/10747 If it requires hitting buttons to initialize, then you may be in trouble.
http://arduino.cc/en/Tutorial/DigitalReadSerial Will get you started on the serial communication. You'll need to do an Real time clock as well, which you can also look up information for on the website.
Do you mean that the Arduino needs to send a message to the projector via RS232 to tell it to turn on?
That ought to be easy enough to do. You can use either the hardware Serial port on pins 0,1 or a SoftwareSerial port on any digital pins you wish, to output TTL serial output. You will need to know the serial port settings (speed, stop bits and parity bits). You will need a driver to convert the serial output by the Arduino from TTL signaling to RS232 signaling. There are various shields and cards to do that and they are not expensive.
If you want the Arduino to managing the timing then you would need to give it Real Time Clock (RTC) capability. IMO it would probably be easier to use a domestic timer to power the Arduino and turn it on at the required time, and then design the Arduino sketch to send the 'on' command each time it powers up.
You don't mention any requirement to turn the projector off. Is there one?
Thanks for all the advise I will look into this
Note: My suggestion was basically doing something along the lines of unplugging it and plugging it back in each time.