Serial port pinout and use

The RS232 standard requires support for baud rates up to 9600 baud on shielded multicore cable up to 50 feet (15 meters) long. For the 4, the use of standard CAT 5 cables enables serial communication at all baud rates up to 50 feet. CAT5 unshielded twisted pair cable lengths much longer than 50 feet have been verified at 9600 baud but are non-standard and are not guaranteed.

The 4 RS232 serial ports are DTE and have the following pin configuration.

Pin		Description	Signal
Pin 1	RTS	Request to send	Output from 4
Pin 2	DCD	Data carrier detect	Input to 4
Pin 3	RXD	Receive data	Input to 4
Pin 4/5		Ground	Signal ground
Pin 6	TXD	Transmit data	Output from 4
Pin 7	DTR	Data terminal ready	Output from 4
Pin 8	CTS	Clear to send	Input to 4

Note Ring indicate (RI) and data set ready (DSR) are not implemented.

The serial ports use a female RJ45 jack to enable connection using UTP Ethernet cabling.