Interface Configuration Guide 7705 SAR Interfaces
Edition: 01 3HE 11011 AAAC TQZZA 413
loopback
Syntax loopback {bidir-b | bidir-e}
no loopback
Context config>port>serial>rs232
config>port>serial>v35
config>port>serial>x21
Description This command puts the specified interface into a loopback mode. The corresponding
interface must be in a shutdown state in order for the loopback mode to be enabled.
In the serial context, a bidirectional loopback B or E may be configured. A bidirectional
loopback is a circuit loopback that loops traffic from the line back to the line and
simultaneously loops traffic from the system back to the system. Bidirectional loopback B
takes place on the control card (CSM) side of the adapter card, and is closer to the system.
Loopback E takes place on the data device side of the adapter card, and is closer to the line.
This command is not saved in the system configuration between boots.
The no form of this command disables loopback on the interface.
Default no loopback
Parameters bidir-b — bidirectional loopback B is closer to the system side of the adapter card
bidir-e — bidirectional loopback E is closer to the line side of the adapter card
multi-drop
Syntax multi-drop {disabled | slave | master}
Context config>port>serial>rs232
config>port>serial>x21
Description This command configures the multidrop data bridge (MDDB) mode. MDDB is a polling
scheme used on SCADA networks (supervisory or control systems used in utility, oil and gas,
and other vertical applications) to communicate with multiple remote terminal units (RTUs)
over a single RS-232 or X.21 link.
In an MDDB, several circuits take turns using the same bandwidth to communicate with one
circuit. Each slave device transmits data in that bandwidth when requested by the master
device. The master device sends polling messages to, and looks for data from, the slave
devices in that bandwidth.
One example of a multidrop data bridge is several terminals taking turns to communicate with
a host computer. The circuit that all the other circuits communicate with is connected to a
master device (a computer) and is designated the master; the rest of the circuits are
connected to slave devices (terminals) and are designated slaves.
To Next Page
Loading...
