User manual

AT COMMAND SET

Section 4

4-16

AT&E ERROR Correction

Parameters : 0 or 1

Default : 0 (MNP disabled)

AT&En enables or disables error correction and data compression in the DPX-213. When

used with the AT&I1 Constant Speed Interface command, the terminal can operate at 4800

bps to 9,600 bps to take full advantage of data compression. Error control or data

compression is not supported at V.21 (300 bps) speeds and in one of the two leased line

modes.

AT&E0 - Error control/data compression disabled.

AT&E1 - MNP-2 to MNP-4 error correction enabled. The highest level automatically

negotiated by modems. If no remote MNP is found, the modem will fall back to

Constant Speed Interface mode or disconnect if AT&I0 is set.

When MNP modems connect, one of the modems must send a request packet (MNP) to

initiate the negotiation. By convention, this is normally the originating modem. If the

modem is connected to a non MNP modem this request will appear as corrupt characters to

the DTE on the non MNP modem. Therefore, the default setting is MNP off.

NOTE: If MNP is to be used, both modems must support it and at least one modem must

request it.

AT&F Load FACTORY Configuration

Parameters : None

Default : None

This command copies the factory defaults from fixed EPROM into working RAM. This is

useful for restoring the modem to a preset configuration. To use the factory defaults in

normal operation, type

at&fK

then make them permanent by typing

at&wK

AT&G GUARD Tone Control

Parameters : 0 or 1

Default : 0 (no Guard Tone)

Guard tone is typically used to disable echo cancellers within the U.K. It is only active in

1200 bps and 2400 bps operation. The modem sends guard tone to line to disable echo

suppressors. Echo suppressors are desirable for voice lines where one party talks and the

other listens, but undesirable for full duplex data lines where both ends are transmitting

simultaneously. Echo suppressors are rarely used in Australia. Guard tones are only active

when operating in V.22bis mode, and only on the answering modem.

AT&G0 - No Guard Tone.

AT&G1 - 1800Hz or 550Hz Guard Tone (depends on Bell setting, ATB0 enables 1800Hz).