User manual

2-18 AT COMMANDS: DATA MODEM

%C – Authorise Data Compression

By using the %C command, you can select data compression for MNP or V.42.

For the compression to work, the remote modem must also have the capability for

data compression and a Reliable mode (\N2, \N3 or \N4) must be active.

AT%C0 Compression not authorised

AT%C1 MNP 5 compression authorised

AT%C2 V.42bis compression authorised

AT%C3 Both compression procedures authorised (factory setting)

➮ Where ﬁles selected for transmission are compressed, the speed of transmis-

sion is reduced with MNP5 or V.42 Protocols.

%E – Automatic Retrain

This command determines whether the modem will try to synchronize again with

the remote modem, if conditions change on the telephone line.

AT%E0 Automatic Retrain not authorised (factory setting)

AT%E1 Automatic Retrain when line conditions deteriorate

%F – 75Tx/1200Rx or 1200Tx/75Rx in V.23 Mode

This command sets the transmission direction of the 75 or 1200 bps channel. This

must ﬁrstly be enabled with the W1 command.

*H – Handshake Speed with MNP 10 Modem:

This command controls the Handshake speed before an MNP 10 connection is

agreed.

AT*H0 Handshake at maximum possible speed (factory setting)

AT*H1 Handshake at 1200 bps

*C – Password for Remote Conﬁguration

When AT*C is entered, the modem will issue a message OLD PASSWORD. The

factory setting for this is the password QWERTY. Only when you have entered the

correct old password will you be given the request NEW PASSWORD. Then, you

can enter your own password (an alpha-numeric sequence of between 6 and 12

characters) and then, when you receive the message and request CONFIRM, you

must repeat it. This stores your new password. The local modem can only be con-

ﬁgured by a remote modem of the same type when this password is recognised.

➮ Remote conﬁguration will function only with MNP connections (AT\N5).