Give me general details of AT Commands?

Answer 1

AT - "Attention!"

+++ - "Escape Sequence"

, - "Pause"

A/ - "Repeat Sequence"

ATA - "Answer Mode"

Bn - "Select Communication Protocol"

Cn - "Transmission Carrier"

Dn - "Dial Control"

En - "Echo"

Fn - "Data Mode Echo"

Hn - "Hook Select"

In - "Report Modem Information"

Ln - "Set Speaker Volume"

Mn - "Set Speaker Mode"

Nn - "Automode Selection/Detection"

On - "Retrain Selection"

P - "Pulse Dialing"

Qn - "Result Codes to DTE"

Sn=x - "Status Registers"

T - "Tone Dialing"

Vn - "Format of Result Code"

Wn - "Extended Result Codes"

Xn - "Result Codes for Call Progress"

Yn - "Long Space Disconnect"

Zn - "Soft Reset and Restore"



Verbosely Referenced Commands



AT - "Attention!" - This command tells the modem that a command follows it.



+++ - "Escape Sequence" - This command initiates an escape sequence to return the modem to the on-line command mode.



, - "Pause" - The Comma normally initiates a 1-5 second pause, however is sometimes used as a command separator in +MS and other commands.



A/ - "Repeat Sequence" - This repeats the previous command. This command will not function properly if preceded by the AT command or followed by .



ATA - "Answer Mode" - This command initiates the modem into an auto-answer mode.



Bn - "Select Communication Protocol" - This command selects the v.22 or Bell 212A protocols for data calls.

B0 - ITU-T v.22 (300bps or 1200bps)

B1 - Bell 212A (300bps or 1200bps)

(There is sometimes a B2 that enables v.23)



Cn - "Transmission Carrier" - This command controls the switching of the transmit carrier.

C0 - Transmit carrier disabled

C1 - Transmit carrier enabled



Dn - "Dial Control" - This command dials the phone number with accordance to the modifiers of n.

DL - Redial the last dialed number

DP - Pulse dial

DR - Enable answer mode

DS=x - Dial the stored telephone number in x

DT - Tone dial

DW - Resume dialing after dial tone is detected

D, - Pause before dial

D"555-4NET" - Letters enclosed in quotes will be dialed as their corresponding numbers on the dialpad.

D! - Enable "flash". (modem can go off hook for a specified amount of time before returning on hook)

D@ - Modem will wait for a quiet answer before dialing the rest of the dial string



En - "Echo" - This command controls whether the modem echos commands received by the DTE or not.

E0 - Echo Disabled

E1 - Echo Enabled



Fn - "Data Mode Echo" - This command controls whether the modem echos commands sent while in data mode.

F0 - Echo in data mode enabled

F1 - Echo in data mode disabled



Hn - "Hook Select" - This command determines whether the modem is on-hook (hangs up) or off-hook (picks up).

H0 - On-hook

H1 - Off-hook



In - "Report Modem Information" - This command reports selected information about the modem.

I0 - Modem model and speed

I1 - ROM checksum

I2 - Tests ROM checksum THEN reports it

I6 - Data connection info

I7 - Manufacturer and model info



Ln - "Set Speaker Volume" - This command controls the speaker volume of the modem.

L0 - Mute

L1 - Low volume

L2 - Medium volume

L3 - High volume



Mn - "Set Speaker Mode"

M0 - Disable speaker

M1 - Enable speaker until a carrier signal is detected

M2 - Enable speaker

M3 - Enable speaker after dialing but disable after a carrier signal is detected



Nn - "Automode selection/detection" - This command is usually more basic (a simple N0 for disabled, N1 for enabled) on 56k modems where automode is more often controlled by an s-register or the +MS command. The full basic Nn command is included for completeness.

N0 - Disable automode

N1, N2, N3, N4, and N5 - Enable automode. Originate mode and Answer mode v.XX attempts will vary from register to register. The N2-N5 commands will not normally be used by 56k modems.



On - "Retrain Selection" - Confusing command that probably should never have been created as it uses an O rather than a 0 and can often be confused. It enables or disables retraining.

O0 - Retraining disabled in on-line command mode

O1 - Retraining enabled in on-line command mode



P - "Pulse Dialing" - This command sets the modem to pulse dial. This command can be duplicated by DP.



Qn - "Result Codes to DTE" - This command selects whether the modem sends result codes to the DTE or not.

Q0 - Enable result codes to DTE

Q1 - Disable result codes to DTE



Sn=x - "Status Registers" - This command writes to or reads data from S-register n. The data written is represented in the place of x. The data used in read mode is selected by the value in x. S-registers can vary a great deal, please consult the AT Command Set specific to your modem when attempting to use these.



T - "Tone Dialing" - This command sets the modem to tone dial. This command can be duplicated by DT.



Vn - "Format of Result Code" - This command selects the format for information-text and result codes.

V0 - Numeric format

V1 - Word (verbose) format



Wn - "Extended Result Codes" - This command enables selection of extended result codes.

W0 - Enables the CONNECT result codes to report the DTE speed.

W1 - Enables the CONNECT result codes to report the DTE speed.

W2 - Enables the CONNECT result codes to report the DCE speed.



Xn - "Result Codes for Call Progress" - This command selects tone detection and result code formatting options.

X0 - Disable busy and dialtone detection. Result codes 0-4 enabled.

X1 - Disable busy and dialtone detection. Result codes 0-5,10 enabled.

X2 - Disable busy detection, enable dialtone detection. Result codes 0-6,10 enabled.

X3 - Enable busy detection, disable dialtone detection. Result codes 0-5,7,10 enabled.

X4 - Busy and dialtone detection enabled. Result codes 0-7,10 enabled.



Yn - "Long Space Disconnect" - This command tells the modem whether or not to disconnect if a 1.6 second break is detected.

Y0 - Long space disconnect disabled

Y1 - Long space disconnect enabled



Zn - "Soft Reset and Restore" - Restores modem profiles that are saved in non-volatile RAM. Refers itself to the &W command.

Z - Soft Reset, basic default restore

Z0 - Restore setting 0

Z1 - Restore setting 1