Accessing the platform - JavaTech: An Introduction to Scientific and Technical Computing with Java - page 638

Table 23.1 Pin assignments for the DB9 serial connector.

Pin Name Abbreviation Direction Function 1

1 Carrier Detect CD In Modem &

destination
modem connected

2 Receive Data RD In Data from modem

3 ransmit Data TD Out Data to modem

4 Data Terminal

Ready

DTR Out Computer ready to

send & receive

5 Ground GND Common -

6 Data Set Ready DSR In Modem ready to

send & receive

7 Request to Send RTS Out Computer waiting

to send

8 Clear to Send CTS In Modem ready to

receive

9 Ring Indicator RI In Modem says phone

is ringing

1

The pin function descriptions here are for the case of a computer con-
nected to a modem.

The SerialPort class provides a single method to set the baud rate, number
of data bits, number of stop bits, and the parity:

void SetSerialPortParams (int baud, int dataBits, int
stopBits, int parity)

If a port does not support any of the values passed in the parameters, the method
throws the UnsupportedCommOperationException .
The SerialPort class includes a set of constants to use for these parameters,
such as:

DATABITS - 7
DATABITS - 8
STOPBITS - 1
STOPBITS - 2
PARITY - NONE
PARITY - EVEN
PARITY - ODD

The two devices connected via the serial line need flow control settings to deter-
mine who is sending and who is receiving and when to switch between the two
states. The XON/XOFF and RTS/CTS are the two primary protocols for this. The