3Com 3C13755-US - Router 5642 Installation Manual page 94

92 A A: C S
PPENDIX ABLE PECIFICATIONS
Table 58 Transmission Rate and Transmission Distance of V.24 (EIA/TIA-232)/V.35 Cable
V.24 (EIA/TIA-232)
Maximum
transmission
Baud rate (bps) distance (m)
4800 60
9600 30
19200 30
38400 20
64000 20
115200 10
- -
The baud rate should not exceed 64 Kbps when the V.24 cable operates in
synchronous mode.
DTE and DCE Mode
The synchronous serial interface 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 59 Typical DTE and DCE
Type of Equipment
DTE
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.
The synchronous/asynchronous serial port cable is connected to a DB-50
receptacle. Proper connection cable needs to be selected for the protocol applied.
Four types of synchronous/asynchronous serial port cables are available. However,
these cables are optional and you must select the proper one based on your
requirements when you purchase the router All these types of cables have a DB-50
adapter at one end.
At the network end, the connector is different for each type of cable, as described
in the following list:
V.24 (EIA/TIA-232) DTE cable — DB-25 (male) adapter
V.24 (EIA/TIA-232) DCE cable — DB-25 (female) adapter
V.35
Baud rate (bps)
4800
9600
19200
38400
54000
64000
2048000
Type of Interface
male
female
Maximum
Transmission
distance (m)
625
312
156
78
60
50
30
Typical Equipment
PC or router
Modem, multiplexer or
CSU/DSU