Serial And Parallel Interface Ports - Biostar M6VCG User Manual

1.5 Serial and Parallel Interface Ports

This system comes equipped with two serial ports and one parallel port. Both types of interface ports will be
explained in this chapter.
The Serial Interface Port : COM1 / COM2
The serial interface port is sometimes referred to as an RS-232 port or an asynchronous communications
port. Mice, printers, modems and other peripheral devices can be connected to a serial port. The serial port
can also be used to connect your computer with another computer system. If you wish to transfer the
contents of your hard disk to another system it can be accomplished by using each machine's serial port.
The serial ports on this system has two 9-pin connector. Some older computer systems and peripherals
used to be equipped with only one 25-pin connector. As you need to connect your 9-pin serial port to an
older 25-pin serial port, you can purchase a 9-to-25 pin adapter.
Connectivity
The serial port can be used many ways, and it can be necessary to become familiar with the pin-out diagram.
The following chart gives you the function of each pin on the 9-pin connector and some of the 25-pin
connector. This information can be used when configuring certain software programs to work with the serial
port.
Signal
DCD
RX
TX
DTR
GND
DSR
RTS
CTS
RI
Special Applications
There are two types of serial devices that can be connected to a serial port. One of the devices is called
"DTE" (Data Terminal Equipment) and the other device is called "DCE" (Data Communications Equipment).
If a modem is connected to a computer, for example, the modem is called the DCE and the computer is
called the DTE. In situations such as this, the pins on the serial ports can be connected straight through.
In instances when there are two DTE devices connected together, such as a computer and a printer, a
special adapter called a "Null Modem" is needed to make communication between the two devices possible.
When using the serial port to communicate between devices, one problem in particular may arise. Some
manufacturers use one set of signals to begin communication with another device and other manufacturers
do not use these signals to initiate communication. If you encounter a communication problem that cannot
be resolved using a null modem, it can generally be assumed that one device is using the initialization
Name
Data Carrier Detect
Receive Data
Transmit Data
Data Terminal Ready
Signal Ground
Data Set Ready
Request to Send
Clear to Send
Ring Indicator
DB9 PIN DB25 PIN
1 8
2 3
3 2
4 20
5 7
6 6
7 4
8 5
9 22
10
Motherboard Description