3Com 10014299 manual Select work clock, Working modes have different working clocks

Synchronous Serial Interface 125

Perform following commands in synchronous serial interface view.

Table 112 Set the digital signal encoding format of synchronous serial interface

Operation	Command
Using NRZI encoding format	code nrzi
Using NRZ encoding format	undo code

By default, the digital signal encoding format of synchronous serial interface is NRZ.

5	Set baud rate
	Please use the following command in the view of the synchronous serial interface.
	Table 113 Set the baud rate of synchronous serial interface
		Operation	Command
		Set baud rate of the synchronous serial	baudrate baudrate
		interface
	When two synchronous serial interfaces are connected, the baud rate on line is
	determined at DCE-side. Therefore, when the synchronous serial interfaces are
	working in DCE mode, the baud rate is to be set. However, if the interfaces act as
	DTE, then the baud rate need not be configured. Default baud rate of
	synchronous serial interface is 64000 bps.
	After the synchronous/asynchronous serial interface is set to synchronous mode
	from asynchronous mode, the system will automatically change the default baud
	rate to 64000 bps.
6	Select work clock
	The synchronous serial interface works in two modes: DTE and DCE. Different
	working modes have different working clocks.

■ If the synchronous serial interface is used as DCE, it is necessary to provide clock to the opposite DTE by choosing DCEclk.

■ If the synchronous serial interface is used as DTE, the clock provided by the opposite DCE needs to be accepted. As the receiving clock and transmitting clock of the synchronous equipment are independent, the receiving clock of DTE can be the transmitting clock or receiving clock of DCE or the sending clock of DTE can be the transmitting clock or receiving clock of DCE. Thus, there will be four combinations, i.e. four kinds of clock selections are available at DTE side.

Figure 46 Schematic diagram of synchronous serial interface clock selection

DCE

TxClk

RxClk

DTE

Table 114 Selection method with synchronous serial interface serving as DTE-side clock

Selection method

Meaning