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194 CHAPTER 11: FUNDAMENTAL SERIAL INTERFACE CONFIGURATION COMMANDS
Parameter dsr-dtr: Detects DSR (data set ready) and DTR (data terminal ready) signals of
DSU/CSU (data service unit/channel service unit).
dcd: Detects the DCD (data carrier detect) signal of the DSU/CSU on the serial
interface.
Description Use the
detect command to enable data carrier detection as well as level
detection on the serial interface.
Use the
undo detect command to disable data carrier detection as well as level
detection on the serial interface.
By default, data carrier and level detection is enabled on serial interfaces.
If level detection is disabled on an asynchronous serial interface, the system
automatically reports that the state of the serial interface is up with both DTR and
DSR being up without detecting whether a cable is connected. If level detection is
enabled on the interface, the system detects the DSR signal in addition to the
external cable. The interface is regarded up only when the detected DSR signal is
valid. Otherwise, it is regarded down.
When determining whether a synchronous serial interface is up or down, the
system by default detects the DSR signal, DCD signal, and presence of cable
connection. Only when the three signals are all valid will the interface be regarded
up. If level detection is disabled, the system considers that the interface is up with
both DTR and DSR being up after detecting the cable connection.
n
The modem command and the undo detect dsr-dtr command are mutually
exclusive.
Example # Enable data carrier detection on synchronous serial interface 2/0.
<Sysname> system-view
[Sysname] interface serial 2/0
[Sysname-Serial1/0] detect dcd
eliminate-pulse
Syntax eliminate-pulse
undo eliminate-pulse
View Asynchronous serial interface view
Parameter None
Description Use the
eliminate-pulse command to eliminate the pulses with a width less than
3.472 us, thus increasing signal reliability. This is useful when the line is seriously
interfered.