Hi, what's the difference between modes in serial instructions such as serin and serout? what's the difference between (for example) T2400 and N2400 and OT2400 and ON2400? when i should use them and in which situation and for what applications?
T means when it sends a '1' the output is high. This is true logic that you would feed into an RS232 level shifter like a MAX232 for example
N means when it sends a '1 the output is low, this simulates RS232 logic levels where a '1' is represented by a low voltage level and a '0' by a high voltage level.
O means the output 'simulates' an open collector configuration, driving the line low, but letting it float high.
This is all explained clearly in the documentation. You should read it.