4
4.0 AT Commands
Each command line must start with the AT prefix and be terminated with a
carriage return (CR). Several commands may be included on one command line.
A command line may contain up to 40 characters, excluding the AT prefix and the
terminating CR. A separator is not required between data commands. A
semicolon (;) separator is required between fax commands.
AT commands are composed of 10-bit ASCII encoded asynchronous
characters. The character format in data mode is 8 data bits with no parity, or 7
data bits with even, odd, or no (two stop bits) parity, at a data rate of 19,200, 2400,
1200, or 300 bps. The character format in fax mode is 8 data bits with no parity at
19,200 bps.
Table 4-1 lists result codes and messages. Table 4-2 summarizes the AT
command set. Table 4-3 summarizes the fax command set.
Table 4-1. Result Codes and Messages
Digital Code
Word Code
Meaning
0
1
2
3
4
OK
Command line executed without errors
Connection at 300 bps
CONNECT
RING
Ringing signal detected
NO CARRIER
ERROR
Carrier lost or never present
Invalid command, checksum, error in
command line, or command line exceeds 40
characters
5
6
7
8
CONNECT 1200
NO DIALTONE
BUSY
Connection at 1200 bps
No dial tone detected
Busy signal detected
NO ANSWER
No silence detected when dialing a system not
providing a dial tone
10
+F4
13
CONNECT 2400
+FCERROR
DATA
Connection at 2400 bps
Fax carrier error
Connected as data modem during auto answer
Connected as fax modem during auto answer
15
FAX
D224ATLVDSC
Conexant
4-1
CONEXANT [ CONEXANT SYSTEMS, INC ]
