Can somebody sent documents for serial port use? (input and output)

Thanks:
Jari Laine
jalai(at)luukku(dot)com

PS. Sorry my terrible language.

I'm interested to use serial output too.
And how can I use serial INPUT? Is there some document for this?
(I try logging data from EFI EURO6 box serial output)

Any serial data info is greatly pleasing.

Best Regards:
Jari Laine
jalai(at)luukku(dot)com

Edit. I have DL1.