ZyXEL Communications Comet 336P Quick Tips when issuing AT Commands, Command Description

Quick Tips when issuing AT Commands

∙The ENTER or RETURN key must be pressed to execute a command.

∙Multiple AT commands can be combined into one line. For example, AT&D2 and AT&N0 can be combined into one line AT&D3&N0.

The Comet processes commands from left to right. The AT command that appears to the right might over-write the command to the left if they are trying to accomplish tasks or set modes that cannot coexist.

∙If you see duplicated characters for each one you type, your Comet and software both have their “echo” feature turned. The Comet command echo state is switched off using ATE0 and on using ATE1 (default). To eliminate the double characters, turn off the software’s command echo rather than using the ATE0 command. If you see no characters in your terminal window when you type, the modem’s echo setting is probably set to off. In this case, issue the ATE1 command.

∙When a command is successfully issued and accepted, a modem responds with what is called a “Result Code.” The Comet supports both “verbose” result codes (i.e. “OK”), and “numerical” result codes (i.e. “0").

You can use the ATV command to set it one way or the other as follows:

Command

Description

ATV0

ATV1

Select numerical result code

Select verbose result code

There are a few basic commands that do not require the “AT” command prefix. These are as follows:

Command	Description
A/	Repeats the last issued AT command once
<any key>	Terminates the current connection attempt, if pressed
	while modem is handshaking.

+++Escape code sequence. Entered while the modem is in Data Mode. Returns modem to Command Mode.

The Comet supports several groups of AT commands:

AT Command Set/Type

Example

Basic AT (Hayes compatible)	ATB0
Basic AT$ (on line help)	AT$
Extended AT& commands	AT&N0
Extended AT* commands	AT*E0

12 Basic Modem Operation