the transmitter does not store any data at all. It just "translates" the DMX data (RS485) into another protocol (usually uart) which ist sent to a microcontroller or microprcessor immideately. The uC or uP then is able to store and work with the data.

There is a lot of hardware and software availabe in the www. But it is impossible to say this one is good, that one is not. It depends very much on what you are going to do with it. Party-Light? Disco? Theater? Very different ways of working, so very differend kinds of software needed.

Sebastian