Here is my RS232 shield. It uses a MAX232 chip to set the right signal levels for real RS232 communication. This shield is fairly unique in that it allows you to implement hardware handshaking (CTS/RTS) through two standard digital pins. http://hacking.majenko.co.uk/rs-232-shield

RS232 (MAX232) shield with hardware handshaking

CrossRoads January 12, 2012, 2:50am 7

Why not beef it up some - add a dual SPI or I2C UART and the MAX232 to your Uno.

NXP Semiconductors SC16IS752 for instance.
Adds dual serial and 8 general purpose IO to your design.

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