W&T 58620, Руководство пользователя

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38
W&T
Modem Operation
5.3 Command and data mode
The LAN-Modem distinguishes on the serial side between two
mode states: command and data mode.
• Command mode
In this mode, which is activated after power-on, the AT
command interpreter operates on the serial interface. The
LAN-Modem is in this state ready to receive and process AT
commands. All data not corresponding to AT syntax is
ignored or acknowledged with an error message. Nothing is
passed on to any communications partner in the network.
The command ATO can be used to switch from command
to data mode during any existing network connection.
• Data mode (Online mode)
This mode is only available while there is a connection to a
communications partner. The AT command interpreter is
now deactivated and all incoming serial data are passed into
the network without any further processing. To switch back
into command mode, use the escape sequence „+++“. To
retain the binary transparency of data mode inspite of the
processing of this character string, the LAN-Modem only
carries out the change if the following times are observed:
minimum 1s no data received
r
Escape sequence
r
1s no data received
If this procedure should be unusable in sepcial cases, the S
registers 2 and 12 can be used to modify the Escape
characters as well as the pause time (see command
Sn=x ).
As an alternative to use of the Escape sequence, the RS232
input DTR can be configured for switching into command
mode. FOr details, see the description of the AT command
&Dn .