 |
What is Serial Transmission?
- Data means to represent information as a binary code, one’s and zero’s, 1’s and 0’s.
- Each one or zero is called a bit.
- The process of representing information as one’s and zero’s is called encoding.
- The process of transmitting one’s and zero’s by sending each bit one at a time over one pathway is called serial transmission.
When your modem talks to your computer via a serial cable only two wires carry the data back and forth. To allow the data from the computer to travel further the data is sent as much larger voltages, plus or minus 15V, this is commonly known as RS232. It should be noted that RS232 actually only defines the DB 25 pin connector.To define how the data is actually sent, one must refer to an international code such as V22 or V22bis.
Pin assignments
DB-25 |
| 2 |
TD |
Transmit Data |
| 3 |
RD |
Receive Data |
| 4 |
RTS |
Request to send |
| 5 |
CTS |
Clear to send |
| 6 |
DSR |
Data Set Ready |
| 7 |
SG |
Signal Ground |
| 8 |
DCD |
Data Carrier Detect |
| 20 |
DTR |
Data Terminal Ready |
| 22 |
Ring |
Ring Indicator |
|
Pin Assignments
DB-9 |
| 1 |
DCD |
Data Carrier Detect |
| 2 |
RD |
Receive Data |
| 3 |
TD |
Transmit Data |
| 4 |
DTR |
Data Terminal Ready |
| 5 |
SG |
Signal Ground |
| 6 |
DSR |
Data Set Ready |
| 7 |
RTS |
Request to Send |
| 8 |
CTS |
Clear to Send |
| 9 |
Ring |
Ring Indicator |
|
|
USB Socket as seen on
Computer Cabinet |
|
 |
|
Pinout Description on Motherboard |
| Pin No. |
Name |
Description |
| 1 |
VCC |
+5voltage
(max. 500mAmp) |
| 2 |
D- |
Data - (Input to
computer) |
| 3 |
D+ |
Data + (Output
from computer) |
| 4 |
GND |
Ground for
voltage |
|
|
