Defining Synchronous Devices

Synchronous devices are identified in the file link.conf by the keyword sync_device, which starts each definition.

Synopsis

Synchronous device definitions have the following general form:

sync_device      syncdevn
    unix_device  device_name
    line_speed   line_speed
    tx_clock     txc
    rx_clock     rxc

Keywords

sync_device syncdevn

Mandatory parameter for synchronous devices. Indicates the start of a synchronous device definition, and assigns a name to the device.

unix_device device_name

Mandatory parameter for synchronous devices. Identifies the serial port used for synchronous communication, and associates the synchronous device with one of the synchronous paths defined in the file ppp.conf. The value device_name must be the device name of a synchronous serial interface installed in your machine.

For example, device names of the form zshn associate the path with one of the on-board serial interfaces. The device names of the form hihn, associate the path with a high-speed serial interface (HSI).

line_speed line_speed

Mandatory parameter for synchronous devices when internal clocking is selected. The optimum line speed is dependent on the serial device selected. The default value proposed is the optimum line speed for one of the onboard serial interfaces (zsh). Refer to the manufacturer's documentation, if you are using a different serial device.

tx_clock txc

Mandatory parameter for synchronous devices. Specifies the source of the transmit clock signal. The value txc can be baud (internal clocking using system baud rate), txc (external clocking using the signal on the transmit pin), or rxc (external clocking using the signal on the receive pin). The transmit clock is most commonly set to baud (internal clocking), or txc (external clocking).

rx_clock rxc

Mandatory parameter for synchronous devices. Specifies the source of the receive clock signal. The value rxc can be baud (internal clocking using system baud rate), txc (external clocking using the signal on the transmit pin), or rxc (external clocking using the signal on the receive pin). The receive clock is most commonly set to rxc, for both internal and external clocking.

Examples

The following synchronous device definition uses a high-speed serial interface (hih) and external clocking:

sync_device           syncdev0
    qqunix_devicee    hih0
    line_speed        0
    tx_clock          txc
    rx_clock          rxc

The following synchronous device definition uses one of the onboard serial interfaces (zsh) and internal clocking:

sync_device      syncdev0
    unix_device  zsh0
    line_speed   19200
    tx_clock     baud
    rx_clock     rxc