User's Manual

3.0 Modem Setup Options

The Turnaround Delay option is available for 208 mode. It is intended for

circuits where echo is a problem. It prevents the Modem from receiving an

echo of its own transmitted data. When the Turnaround Delay option is on,

CD (pin 8) is held low for 150 ms after RTS is turned off. If the modem

detects an energy loss during the delay, it turns CD on 52 ms after detecting

the loss. If the modem does not detect an energy loss, it turns CD on 52 ms

after the end of the delay. The modem ignores any energy loss during the

first 8.5 ms.

The Analog Loopback Make Busy is available for all modes. If the Analog

Loopback Make Busy option is enabled, the Modem provides a busy

indication to the dial line interface when the Modem is in analog loopback

test mode.

The Selective Retransmission option is for Hayes,V.25 bis, Dumb, and Leased-

Line modes (except V.33). This option allows the Modem to communicate

with certain modems that are not able to respond to the MNP selective

retransmission command.

• Enable — This setting allows the modem to request retransmission

of a single information frame (in the event of a transmission error).

• Disable — Data can only be retransmitted in a series of information frames.

The DCE Pass-Through Flow Control option is for Hayes,V.25 bis, Dumb,

and Leased-Line modes (except V.33)

This option affects DCE–DTE flow control only. It is only effective if error

correction or buffer mode/speed conversion is ‘enabled’.

• Enable — The Modem will pass flow control characters received from

the remote modem to the local DTE.

• Disable — The Modem will not pass flow control characters from the

remote modem to the local DTE.

The Link Flow Control option is for Hayes,V.25 bis, Dumb, Leased-Line

modes (except V.33)

This option is effective only if buffer mode/speed conversion is enabled

and an error-correction link is not established.