Compatible Systems 5.4 - Manual (Page 226)

220 Chapter 14 - General
Tx Clock Internal (Sync Only)
This parameter determines whether the interface will source a clock signal or
expect to receive an external clock.
• If checked, the interface will expect to source a clock, and will ignore an
external clock signal.
• If unchecked, the interface will expect to receive an external clock. This
is the default setting.
v Note: In addition to this setting, some WAN interfaces require internal
hardware jumpers to be changed in order to source a clock signal. Check the
Installation Reference Guide for the device.
Baud Rate
This pull-down menu determines the speed of the port’s internal clock. In
Async operation, this value must match the baud rate of the external commu-
nications device. In Sync operation this value is ignored unless Tx Clock
Internal is checked, in which case it determines the speed of the clock which
is sourced.
Flow Control (Async Only)
This setting determines the type of flow control used on interfaces set for
Async operation.
• If none is selected, the interface will not pace the rate at which it sends
characters.
• If hardware is selected, the interface will use the state of the CTS (Clear
To Send) line to determine whether characters may be sent. This is the
default setting.
• If XOn/XOff is selected, the interface will trap XOn and XOff characters
to determine whether characters may be sent. This method is also known
as “software” flow control.
v Note: You may also need to configure your communications device
(through switch settings or internal registers) to run with software flow
control. Software flow control is not recommended at speeds above 9600
Baud.