T
ECHNICAL
Q
UICK
R
EFERENCE
173
Serial Interface Pin Definitions
Signal Source
DB-25 DB-9 Circuit
Function
Computer/Modem
1
—
AA
Chassis Ground
Both
2
3
BA
Transmitted Data
Computer
3
2
BB
Received Data
Modem
4
7
CA
Request to Send
Computer
5
8
CB
Clear to Send
Modem
6
6
CC
Data Set Ready
Modem
7
5
AB
Signal Ground
Both
8
1
CF
Carrier Detect
Modem
12
—
SCF
Speed Indicate
Modem
20
4
CD
Data Terminal Ready
Computer
22
9
CE
Ring Indicate
Modem