RS232 Shield is a standart interface for equipment. You can now easily access those equipment straight from your Arduino.
The RS232 shield have DB9 connectors that provide connection to various devices with RS232 interface.
For show of communicating of data RXD/TXD have 2 LED for each one chanel.
The Shield is build on MAX232,which is a dual buffer. Shield have extra space with the soldering area, which is highly convenient for prototyping.
Also shield have pinheaders with jumpers for selecting of serial RS232 ports RXD/TXD for option to choose between Arduino I/O D0-D13.
Stackable pinheaders on the back that are compatible with most Arduino controllers such as arduino Uno, Mega, Leonardo.