Intel 536EX manual 1.4.1Sending Commands, Intel Confidential, Introduction

Introduction

1.4.1Sending Commands

All command lines sent to the modem, except for A/, must be preceded by an ‘AT’ and terminated by the contents of S-register S3 (typically a carriage return <CR>). AT stands for ‘attention’ and prompts the modem to receive a command line from the DTE. A <CR> informs the modem that the entire command string has been transmitted and to begin processing all the commands in the command line. A command line can include one or more AT commands. The commands can be separated by a space, if desired, but no punctuation is needed except for extended commands. Extended commands begin with a ‘+’, such as fax, voice, and V.250 commands. In a multiple- command line, extended AT commands must be separated from following commands by a semicolon(;).

Examples:

ATS1?<CR>

A/

AT &F &D2 +FCLASS=?<CR>

AT +FCLASS=0; S0=1<CR>

The modem provides status information to the DTE in the form of response codes, as listed in Table 4. Response codes take two (2) forms, text (ATV1) or numeric (ATV0), depending on how the modem is configured.

Table 4 lists basic format response codes. These response codes have numeric equivalents that are displayed depending on the value of ATV. In addition to the basic format response codes, there are extended syntax result codes that indicate connection status of the DCE-DCE connection that are not effected by numeric response reporting. These result codes have no numeric equivalent and are always issued in text form. The result codes display modem mode, transmit connection rate, error correction, compression, DTE rate, and receive rate. Note that the final connection message only indicates receive rate if ATXn is greater than 0. The format for the result codes code depends on the Wn command. The setting of the Wn command will determine which of the following connect results codes are displayed (+MCR, +MRR, +ER, +DR, +ILRR). Refer to the Wn command for the detailed description of the command. Note that the supported carrier modes for +MCR can be found in parameter 1 of +MS. The last result code is the CONNECT <text>, where text is the DCE receive rate. Note, the CONNECT <text> is not displayed when ATX0 is indicated, just CONNECT is displayed and is reported by the rules in Table 4.

Table 4. DTE-Modem Data Rate Response Codes

Numeric	Text		Numeric	Text
0	OK	9		DELAYED CALL
1	CONNECT	10		BLACKLISTED
2	RING	11		+FCERROR
3	NO CARRIER	12		RINGBACK
4	ERROR	13		CPON=
6	NO DIALTONE	14		CPOF=
7	BUSY	15		DRON=
8	NO ANSWER	16		DROF=

After sending an AT command string to the modem, the DTE must wait for a response code from the modem before sending a new AT command string to the modem.

12 536EX Chipset Developer’s Manual

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