Modem Signal and Line States

Signal and Line State Diagrams

Closing Modem Connections

Note The modem cts-requiredcommand was replaced by the modem printer command in Cisco IOS Release 12.2.

To configure a line to close connections from a user’s terminal when the terminal is turned off and to prevent inbound connections to devices that are out of service, use the following command in line configuration mode:

Command

Purpose

 

 

Router(config-line)# modem cts-required

Configures a line to close connections.

 

 

Figure 28 illustrates the modem cts-requiredcommand operating in the context of a continuous CTS signal. This form of modem control requires that the CTS signal be high for the entire session. If CTS is not high, the user input is ignored and incoming connections are refused (or sent to the next line in a rotary group).

Figure 28 EXEC and Daemon Creation on a Line Configured for Continuous CTS

Idle state

DTR high, watching

CTS

CTS raised

Close connection,

DTR low for

5 seconds

Hang up

 

 

 

 

 

CTS lowered

 

 

 

 

 

 

 

DTR going

 

 

 

 

DTR high,

 

 

Ready

 

 

 

 

 

 

 

 

 

watching

 

 

 

low

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CTS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

User-typed

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Incoming network

 

 

 

activation

 

 

 

 

 

 

 

Create

 

connection

 

 

 

character

 

 

 

 

 

 

 

EXEC

 

 

Create

 

 

 

 

 

 

 

 

 

 

 

 

daemon

 

Ready

 

DTR high,

 

 

 

 

 

 

 

Ready

 

 

 

 

DTR high,

 

 

 

and

 

watching

 

 

 

 

 

 

 

 

 

 

 

 

watching

 

 

and

 

 

active

 

CTS

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CTS

 

 

active

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

CTS lowered

CTS lowered or

 

 

 

 

 

 

or exit

 

 

 

 

 

 

network

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

connection

S1004a

 

 

 

 

 

 

 

 

 

 

closed

 

 

 

 

 

 

 

 

 

 

 

Cisco IOS Dial Technologies Configuration Guide

DC-162

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Cisco Systems DC-157 manual Closing Modem Connections, DC-162

DC-157 specifications

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