Which cable for 230.4 Kbps RS-232
It's likely working with RS-232, but you need to take a bit of care.


I'd use a shielded cable, standard network cable Cat. 5e or better will do. You can use one pair for RX and one pair for TX. The second wire of each pair can be tied to ground. 
Using just two wires to transmit the data will very likely not work.
230 kBaud should be possible using the driver you mentioned. It is specified up to 1 MBaud at a line capacity of 1 nF. Your 3m cable will be much lower. 
I would add a low-pass filter close to the driver to reduce the slope of the signal and reduce cross-talk and reflections. As every bit has a length of about 5µs, you need an RC-time of less than 1µs, e.g. 1 kOhm in series followed by 100 pF to ground. A termination resistor at the far end might help as well, e.g. 5 kOhm to ground. You might have to play a bit with these values and check the signal quality.