3com 3013 (3C13613) User Manual
54
C
HAPTER
A: O
PTIONAL
C
ABLE
S
PECIFICATIONS
Synchronous and
Asynchronous mode
V.35 and V.24 (EIA/TIA-232) standards support synchronous operating mode,
while only V.24 (EIA/TIA-232) standard supports the asynchronous operating
mode. The maximum transmission distance and baud rate of the signal vary with
the operating mode. See Table 29 for details.
while only V.24 (EIA/TIA-232) standard supports the asynchronous operating
mode. The maximum transmission distance and baud rate of the signal vary with
the operating mode. See Table 29 for details.
Table 29 Transmission Rate and Transmission Distance of V.24 (EIA/TIA-232)/V.35 Cable
CAUTION: The baud rate should not exceed 64 Kbps when the V.24 cable
operates in synchronous mode.
operates in synchronous mode.
DTE and DCE mode
The synchronous serial port can operate in both DTE mode and DCE mode. For
two devices connected directly, one device should operate in DTE mode, and the
other device should operate in DCE mode. The DCE mode device provides a
synchronous clock and specifies the transmission rate, the DTE mode device
accepts the synchronous clock and communicates at the specified transmission
rate. Usually, the router serves as the DTE device. To determine whether the device
is a DTE or a DCE, refer to the user manual for the device. Table 30 helps identify
DTE and DCE devices.
two devices connected directly, one device should operate in DTE mode, and the
other device should operate in DCE mode. The DCE mode device provides a
synchronous clock and specifies the transmission rate, the DTE mode device
accepts the synchronous clock and communicates at the specified transmission
rate. Usually, the router serves as the DTE device. To determine whether the device
is a DTE or a DCE, refer to the user manual for the device. Table 30 helps identify
DTE and DCE devices.
Table 30 Typical DTE and DCE
In general, the asynchronous serial interface is connected to a modem or a
terminal adapter (TA) to act as the dial-up interface. In this case, it is unnecessary
to determine whether the device is DTE or DCE, you must only select the
appropriate baud rate.
terminal adapter (TA) to act as the dial-up interface. In this case, it is unnecessary
to determine whether the device is DTE or DCE, you must only select the
appropriate baud rate.
V.24 (EIA/TIA-232) DTE
Cable Pinouts
Figure 30 illustrates the V.24 DTE cable
V.24 (EIA/TIA-232)
V.35
Baud Rate (bps)
Maximum
Transmission
Distance (m)
Transmission
Distance (m)
Baud Rate (bps)
Maximum
Transmission
Distance (m)
Transmission
Distance (m)
2400
60
2400
1250
4800
60
4800
625
9600
30
9600
312
19200
30
19200
156
38400
20
38400
78
64000
20
56000
60
115200
10
64000
50
-
-
2048000
30
Type of
Equipment
Equipment
Type of Interface
Typical Equipment
DTE
male
PC or router
DCE
female
Modem, multiplexer or CSU/DSU