3Com MSR 50, MSR 30 manual Dteclk1, 191, Clock selection option Description

191

dteclk3: Sets the interface clock selection mode to DTE clock option 3.

dteclk4: Sets the interface clock selection mode to DTE clock option 4.

dteclkauto: Sets the interface clock selection mode to DTE autonegotiation.

Description Use the clock command to set clock selection mode for the synchronous serial interface.

Use the undo clock command to restore the default.

By default, the DTE-side clock on synchronous serial interfaces is DTE clock option

1(dteclk1).

A synchronous serial interface can operate as DCE or DTE.

■As DCE, the interface provides DCEclk clock to the DTE.

■As DTE, the interface accepts the clock provided by the DCE. As transmitting and receiving clocks of synchronization devices are independent, the receiving clock of a DTE device can be either the transmitting or receiving clock of the DCE device, so is the transmitting clock. Therefore, four clock options are available for a DTE device.

See Figure 1:

Figure 1 Select a clock for a synchronous serial interface

DCE

TxClk

RxClk

DTE

In the figure, “TxClk” represents transmitting clock and “RxClk” receiving clock.

The following table gives the four clock selection options.

Table 16 Clock options available for a synchronous serial interface working as DTE

Clock selection option	Description
DTEclk1	TxClk = TxClk, RxClk = RxClk
DTEclk2	TxClk = TxClk, RxClk = TxClk
DTEclk3	TxClk = RxClk, RxClk = TxClk
DTEclk4	TxClk = RxClk, RxClk = RxClk

In the table, the clock ahead of the equal sign (=) is the DTE clock and the one behind is the DCE clock.

Example # Set the synchronous serial interface working as DTE to use the clock selection option dteclk2.

<Sysname> system-view

[Sysname] interface serial 1/0

[Sysname-Serial1/0] clock dteclk2