3com MSR 20-20 참조 매뉴얼

# Set the MRU of interface serial 2/0 to 1,500 bytes (assuming that the interface is 
an asynchronous serial interface and operates in flow mode).

<Sysname> system-view

[Sysname] interface serial 2/0

[Sysname-Serial2/0] physical-mode async

[Sysname-Serial2/0] async mode flow

[Sysname-Serial2/0] phy-mru 1500 

Synchronous serial interface view

None

Use the reverse-rts command to reverse RTS signal for debugging purpose.

Use the undo reverse-rts command to restore the default.

By default, RTS signal reverse is disabled.

This command is used in hardware flow control where the remote is not allowed 
to send data when the local end is doing that.

# Reverse RTS signal.

<Sysname> system-view

[Sysname] interface serial 1/0

[Sysname-Serial1/0] reverse-rts 

timer hold seconds

Serial interface view, AUX interface view, AM interface view, USB interface view

Seconds: Link state polling interval (in seconds) to be set, in the range 1 to 32,767.

Use the timer hold command to set the link state polling interval.

Use the undo timer hold command to restore the default.

By default, the link state polling interval is 10 second.