Section 13. MODEM "AT" COMMANDS AND "S" REGISTERS
NOTE
The command and register descriptions in this section are provided for informational purposes
only, since the RFL 9660 modem is set up at the factory.
13.1 INTRODUCTION
This section describes the "AT" commands that are used to control the RFL 9660 modem module. The
"S" registers that store values used by many of the "AT" commands are also described in this section.
The AT Command Set is used by the RFL 9660 local port to communicate with modems. A typical command
string begins with the ASCII “A” and “T” or “a” and “t”. The modem uses these first two characters to determine
the data rate, number of bits, and type of parity which the RFL 9660 is employing in its communication. The
modem then buffers the command string in its RAM until a carriage return [CR] or [ENTER] is transmitted. Once
the [CR] is received, the modem begins to execute in order, all of the commands in the string. The number of
characters in this string should not exceed 40. If the modem encounters an illegal command, a command that
cannot be executed, or more than 40 characters, it immediately aborts the execution of the command string and
issues an ERROR message to the RFL 9660. If the command string is proper, the modem will execute all
commands and send an OK message to the RFL 9660.
The modem has one factory default profile and one additional user profile that can be programmed into its non-
volatile memory. To configure the modem to one of these profiles, issue the command:
AT&F0[CR]
for the factory default profile; or
ATZ0[CR]
for the user profile
To store or recall a user profile, use the following commands: Zn, &Wn, or &V, (These commands are
discussed in detail later in this section). In each of the the following command descriptions, the default setting
for the factory profile is indicated where applicable.
Modems are always in one of two modes of operation. The modem enters into Data Mode once a connection
has been established with a remote modem. In Data Mode, any data transmitted from the RFL 9660 to the
remote modem is first modulated and then transmitted to the remote modem; and similarly, any data that the
remote modem transmits to the RFL 9660 has been received from the remote modem and is then demodulated.
The modem can be in Data Mode only when the modem has established a communications link with a remote
modem (The only exception to this is during diagnostic tests - See &Tn commands). At all other times, the
modem is in Command Mode. When in Command Mode, the modem will respond to AT commands issued from
the RFL 9660 local port.
While in Data Mode, if it is necessary to issue commands to the modem without severing the communications
link to the remote modem, an escape sequence may be issued to the modem.
Refer to Section 13.2.2 for more information.
RFL 9660
RFL Electronics Inc.
April 24, 2007
13-1
(973) 334-3100