Compatible Systems 5.4 manual Tx Clock Internal Sync Only, Baud Rate, Flow Control Async Only

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.

ϖNote: 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.

ϖNote: 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.