3Com 3C13618 Command Reference Manual page 131

3Com Router Command Reference Guide — V1.00
DCE
Figure 3-1 Clock selection on the sync serial interface
TxClk stands for transmitting clock and RxClk for receiving clock.
If the synchronous serial interface acts as the DCE, it is necessary to provide clock
for the opposite DTE. So you need to select DCEclk.
If the synchronous serial interface acts as the DTE and receives the clock provided
by the opposite DCE and because the TX and RX clocks of the synchronous
equipment are independent, the RX clock of the DTE can be either of the TX and RX
clocks for the DCE, and the TX clock for the DTE can be either of the DCE's TX and
RX clocks. So this gives rise to four clock combinations, that is, four clocks are
available for selection at the DTE side.
These four selection methods are specified as in the following table.
Table 3-1 Clock selection methods at the serial interface DTE side
DTEclk1
DTEclk2
DTEclk3
DTEclk4
In the above table, TxClk stands for the transmitting clock and RxClk for the receiving
clock. The DTE side clock is before "=" while the DCE side clock is after "=".
For related commands, see physical-mode.
Example
# Set the clock selection method for the synchronous serial interface as the DTE to
DTEclk2.
[3Com-Serial0]clock dteclk2
20
TxClk
DTE
RxClk
Selection method Meanings
TxClk = TxClk, RxClk = RxClk
TxClk = TxClk, RxClk = TxClk
TxClk = RxClk, RxClk = TxClk
TxClk = RxClk, RxClk = RxClk