|
Pin
|
Signal
|
Class |
Direction
|
Description
|
|
1
|
DCD
|
control
|
DCE->DTE
|
Data
Carrier Detect
A
control signal to the PC. The modem is receiving a valid carrier signal
from the remote modem. |
|
2
|
RXD
|
data
|
DCE->DTE
|
Receive
Data
The
data signal to the PC. What the user sees from the remote host. |
|
3
|
TXD
|
data
|
DTE->DCE
|
Transmit
data
The
data signal from the PC. The data sent by the user. |
|
4
|
DTR
|
control
|
DTE->DCE
|
Data
Terminal Ready
A
control signal from the PC used to enable the modem and inform it
that the PC is alive. The modem is allowed to go on-line or answer a call. |
|
5
|
GND
|
|
|
Ground
The
common signal ground connection. All the other signals refer to this reference.
This must be connected at both connectors. |
|
6
|
DSR
|
control
|
DCE->DTE
|
Data
Set Ready
A
control signal to the PC. The modem is ready to answer or originate a call
– as opposed to being in a test mode. |
|
7
|
RTS
|
control
|
DTE->DCE
|
Request
To Send
A
control signal from the PC. The PC is ready to receive data. The PC may
drop RTS from time to time when busy doing other demanding tasks. |
|
8
|
CTS
|
control
|
DCE->DTE
|
Clear
To Send
A
control signal to the PC indicating that the remote host (remote DTE) is
ready to receive your input. |
|
9
|
RI
|
control
|
DCE->DTE
|
Ring
Indicator
A
control signal to the PC. Indicates the phone line is ringing. |
