5-15
PA-8T-232 Synchronous Serial Port Adapter Installation and Configuration
OL-3562-03
Chapter 5 Configuring the PA-8T-232 Interfaces
Configuring Half-Duplex and Binary Synchronous Communications in Cisco 7200 Series Routers
the FCS value to the message. The receiver recalculates the FCS and compares its calculation to the FCS
from the sender. If there is a difference between the two calculations, the receiver assumes that a
transmission error occurred and sends a request to the sender to resend the frame.
Enable 32-bit CRC using the crc 32 command. Before you can enable 32-bit CRC, you must use the
interface serial command (followed by the interface address of the interface) to select the interface on
which you want to enable 32-bit CRC. This command functions in the same way on all supported
platforms.
In the example that follows, 32-bit CRC is specified:
Router(config-if)# crc 32
The preceding command example applies to all systems in which the PA-8T-232 is supported. Use the
no crc 32 command to disable CRC-32 and return the interface to the default CRC-16 (CRC-CITT)
setting.
When you are done, press Ctrl-Z—hold down the Control key while you press Z—or enter end or exit
to exit configuration mode and return to the EXEC command interpreter prompt. Then write the new
configuration to NVRAM using the copy running-config startup-config command.
For command descriptions, refer to the Configuration Fundamentals Configuration Guide publication.
For more information, see the
“Obtaining Documentation” section on page x
and the
Technical Assistance” section on page xi
Note
If you are configuring a PA-8T-232 on a Cisco 7200 series router and you want to configure the interface
for half-duplex or Bisync operation, proceed to the next section
“Configuring Half-Duplex and Binary
Synchronous Communications in Cisco 7200 Series Routers”
; otherwise, proceed to the
Configuration” section on page 5-17
Configuring Half-Duplex and Binary Synchronous
Communications in Cisco 7200 Series Routers
This section explains how to configure EIA/TIA-232 interfaces for half-duplex and Bisync operation in
Cisco 7200 series routers.
Note
Cisco IOS Release 11.2(7a)P or later supports half-duplex and Bisync operation on the PA-8T-232 in
Cisco 7200 series routers.
Cisco IOS Release 12.0(3)T or later or Release 12.0(1)XE or later supports nonstandard clock rates on
PA-8T-232 interfaces installed in Cisco 7204VXR and Cisco 7206VXR routers.
Cisco 7100 series routers, Cisco uBR7200 series routers, the VIP, the Catalyst 6000 family FlexWAN
module, and the Catalyst RSM/VIP2 do not support half-duplex and Bisync operation on the PA-8T-232.
Use the half-duplex command to configure EIA/TIA-232 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.
Controlled-carrier mode sets the EIA/TIA-232 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