3Com 3016 (3C13616), 3015 (3C13615) manual DTE and DCE mode, Cable Pinouts, Typical DTE and DCE

54CHAPTER A: OPTIONAL CABLE SPECIFICATIONS

Synchronous and V.35 and V.24 (EIA/TIA-232) standards support synchronous operating mode, Asynchronous 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.

Table 29 Transmission Rate and Transmission Distance of V.24 (EIA/TIA-232)/V.35 Cable

V.24 (EIA/TIA-232)		V.35
	Maximum		Maximum
	Transmission		Transmission
Baud Rate (bps)	Distance (m)	Baud Rate (bps)	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

CAUTION: The baud rate should not exceed 64 Kbps when the V.24 cable 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.

Table 30 Typical DTE and DCE

Type of	Type of Interface	Typical Equipment
Equipment
DTE	male	PC or router
DCE	female	Modem, multiplexer or CSU/DSU

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.

V.24 (EIA/TIA-232) DTE Figure 30 illustrates the V.24 DTE cable

Cable Pinouts