User manual

AT COMMANDS: DATA MODEM 2-11
&G – Guard Tone
In the Answer mode (upper channel transmission), the unit can send a Guard tone
which in certain circumstances is a requirement for connections to the UK from
abroad. With Bell 212A and Bell 103, no Guard tone is transmitted.
AT&G0,1 Guard tone Off (factory setting)
AT&G2 1800 Hz Guard tone
&K – Flow Check
This command determines the type of computer/modem flow check: -
AT&K0 No flow check authorised
AT&K3 RTS/CTS flow check authorised (standard for data modem opera-
tion), (factory setting).
AT&K4 XON/XOFF flow check authorised
AT&K5 Transparent XON/XOFF flow check
AT&K6 XON/XOFF and RTS/CTS flow check authorised (standard for fax
modem operation)
&M – Asynchronous Dialling / Synchronous Data Transmission
With this command, once the modem has dialled (in asynchronous mode) it can
change over to data transmission in synchronous mode.
AT&M0 Commands and transmission are asynchronous (factory setting)
AT&M1 This mode is used with terminals which can operate asynchro-
nously or synchronously. The modem goes to synchronous mode
for the entire period of data transmission
AT&M2 Same as &M1; in addition, when the S1 (DTR) signal changes
from On to Off, the number stored with AT&Z0 will be dialled.
&Q – Synchronous / Asynchronous
This command extends the functions of the &M command and is used for control-
ling authorised types of connection.
AT&Q0-2 Same as &M0-2
AT&Q4 Hayes Autosync Operational Mode: This modem supports Auto-
sync, the Hayes Method of synchronous communication. Used in
conjunction with the “Hayes Synchronous Interface” (HSI), this
system permits synchronous communication with mainframe com-
puters from an asynchronous terminal (PC). This requires no addi-
tional synchronous PC boards and the modem can change the
operating mode without any configuration modification (see also
Registers 19, 20 and 25).