AT&T 2500 series 用户手册
1-12
TRANSMISSION STATES
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DCE
ORIGINATING
DCE
DESTINATION
SWITCH
RS-232
RS-232
RAW BITS
DCP
DCP
1
DTE
2
DMI
ASCII
ASCII
3-7
USER DEFINED
D
I
G
I
T
A
L
I
G
I
T
A
L
P
O
R
T
O
R
T
D
I
G
I
T
A
L
I
G
I
T
A
L
P
O
R
T
O
R
T
D
I
G
I
T
A
L
I
G
I
T
A
L
P
O
R
T
O
R
T
D
I
G
I
T
A
L
I
G
I
T
A
L
P
O
R
T
O
R
T
DATA
MODULE
DATA
MODULE
DATA
MODULE
DATA
MODULE
DTE
DTE
DATA
MODULE
DS1
PORT
PORT
1
D
I
G
I
T
A
L
I
G
I
T
A
L
P
O
R
T
O
R
T
RAW BITS
RS-232
DS1 FORMAT
DCP
DMI
ASCII
2
P
O
R
R
T
D
S
1
1
DTE
T
R
U
N
K
R
U
N
K
P
O
R
T
O
R
T
A
N
A
L
O
G
N
A
L
O
G
ADU
ADU
DTE
E
I
A
P
O
R
R
T
E
I
A
P
O
R
R
T
DTE
DMI
ASYNCH ASCII
ASYNCH ASCII
2
3-7 USER
DEFINED
RS-232
RS-232
ADU PROT
ADU PROT
1 RAW
BITS
3-7 USER
DEFINED
VOICE GRADE DATA
ASCII
ASCII
2
ANALOG
ANALOG
1
PCM
RS-232
RS-232
P
O
R
T
O
R
T
A
N
A
L
O
G
N
A
L
O
G
L
I
N
E
I
N
E
A
N
A
L
O
G
N
A
L
O
G
P
O
R
T
O
R
T
DTE
DTE
MODEM
POOLING
CABLE
CABLE
MODEM
MODEM
MODEM
PCM
3-7
USER DEFINED
Figure 1-3. Transmission States for Data Transmission