∙Multiple AT commands can be combined into one line. For example, AT&D2 and AT&K0 can be combined into one line AT&D2&K0.
The Comet processes commands from left to right. The AT command that appears to the right might
∙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 commands (compatible) | ATB0 |
Extended AT& commands | AT&D0 |
Extended AT\ commands | AT\N3 |
Extended AT% commands | AT%C1 |
Extended AT- commands | |
ATS0=1 | |
ATS0? |
16 Basic Modem Operation