Arduino: RS232 Level Shifter or RS2323 Breakout needed?
RS-232 is simply a high-voltage inverted UART signal along with various other control signals (CTS, RTS, DCD, etc.). If your controller doesn't require these additional control signals then what you have is sufficient. If you need other control signals then you will need the breakout board as well as additional GPIOs on the Arduino in order to generate these signals, plus the code to generate them, plus a DB-9 breakout board to plug into.