AT Commands and S-Registers
4-113825-A2-GB30-20 November 1996
Table 4-1
(9 of 14)3825
Plus
AT Commands&M
n
or &Q
n
Async/Sync Mode and DTE Dialer Type
Sets the modem for either asynchronous or synchronous operation and selects the type of dialing method the modem
uses.
&M, &M0, &Q, &Q0
Modem operates in Asynchronous mode and uses AT Command protocol.
&M1, &M3, &Q1, &Q3
Modem operates in Synchronous mode and uses AT Command protocol.
&M2, &Q2 Modem operates in Synchronous mode and dials the telephone number stored in directory location 1
when the DTR signal turns Off and then ON.
&M231, &Q231
Modem operates in Asynchronous mode and disables any type of AT command dialing protocol.
&M232, &Q232
Modem operates in Asynchronous mode and uses V.25bis asynchronous dialing.
&M233, &Q233
Modem operates in Synchronous mode and uses V.25bis bisynchronous dialing.
&M234, &Q234
Modem operates in Synchronous mode and uses V.25bis HDLC dialing.
&M235, &Q235 Modem operates in Asynchronous mode and enables a subset of the AT&T command set. This is
required for AT&T DATAKIT dial-out applications.
The &M2, &M231 through &M235, &Q2, and Q231 through Q235 commands disable the use of AT commands and force
the modem into Dumb mode. The only way to regain control of the modem is to recover AT Commands as described in
the
Recovering AT Commands
section in Chapter 2.
&R
n
RTS Action
Request-to-Send (RTS) is a signal from the DTE to the modem indicating the DTE has data to send to the modem.
&R, &R0 Standard RS232. DTE controls RTS to the modem in normal EIA-232-D operation. RTS must be
ON for the DTE to transmit to the modem.
&R1
Ignores RTS. Modem assumes RTS is always ON. Use this selection when the DTE does not
provide RTS to the modem.
&R2 Simulated Control Carrier. RTS input controls the remote modem’s LSD signal. This is used for
DTEs that require Line Signal Detect (LSD) to toggle ON and Off to simulate half-duplex operation.