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Configuring the PA-4T+ Interfaces 8-13
Configuring Half-Duplex
Configuring Half-Duplex
Use the half-duplex command to configure PA-4T+ interfaces for half-duplex mode; full-duplex
mode is the default for low-speed serial interfaces. Serial DCE interfaces in half-duplex mode can
be configured for controlled-carrier mode or constant-carrier mode; constant-carrier mode is the
default. Use the half-duplex controlled-carrier command to configure a PA-4T+ interface for
controlled-carrier mode. Use the no half-duplex controlled-carrier command to return the
interface to constant-carrier mode.
Controlled-carrier mode sets the PA-4T+ interface to deactivate data carrier detect (DCD) until a
transmission is sent to the interface. After a transmission is received, DCD is activated and the
interface waits a user-configured amount of time, then transmits the data. After the transmission, the
interface waits a user-configured amount of time and then deactivates DCD.
Constant-carrier mode activates DCD at all times.
Follow these steps to configure controlled-carrier mode on a PA-4T+ interface:
Step 1 At the privileged-level prompt, enter configuration mode and specify that the console
terminal will be the source of the configuration subcommands, as follows:
Router# configure terminal
Enter configuration commands, one per line. End with CNTL/Z.
Router(config)#
Step 2 Specify the interface to configure for controlled-carrier mode (using the subcommand
interface, followed by the type [serial] and slot/port [port adapter slot number and
interface number] and then the subcommand half-duplex controlled-carrier). The
following example is for the first interface of the port adapter in slot 1:
Router(config)# interface serial 1/0
Router(config-if)# half-duplex controlled-carrier
Step 3 Specifythe time that the interface delays when configured for controlled-carrier mode by
entering the half-duplex timer {cts-delay value | cts-drop-timeout value |
dcd-drop-delay value | dcd-txstart-delay value | rts-drop-delay value |
rts-timeout value | transmit-delay value} command. The following example configures
the DCD drop delay onthe first interface of the portadapter in slot 1 for 100 milliseconds:
Router(config)# interface serial 1/0
Router(config-if)# half-duplex timer dcd-drop-delay 100 ms
Note Table 8-1 lists the default settings for each half-duplex timer.
Step 4 After including all of the configuration subcommands, to complete the configuration,
enter Ctrl-Z (hold down the Control key while you press Z) or enter end to exit
configuration mode and return to the EXEC command interpreter prompt.
Step 5 Write the new configuration to nonvolatile memory as follows:
Router# copy running-config startup-config
[OK]
Router#
This completes the procedure for configuring controlled-carrier mode on a PA-4T+ interface. For
additional information on configuring half-duplex operation on low-speed serial interfaces, refer to
the chapter “Configuring Interfaces” of the Configuration Fundamentals Configuration Guide
publication. If you need more information, see the “Cisco Connection Online” section on page vii
and the “Related Documentation” section on page vi.