Chapter 3 - Basic Modem Operation
3-5
AT Command Set/Type
Example
Fax and Voice AT+ commands
AT+FCLASS=2
S-Register command
ATS0=1
S-Register bit-mapped command
(set S-
Register bit 1 equal to 1)
ATS13.1=1
S-Register inquiry command
ATS0? Or ATS13.1?
You may browse the lists of available commands for each command set by using
the on-line help commands: AT$, AT*$, AT&$, and ATS$. Further detail on AT
commands will be covered in the chapters that pertain to their uses.
Modem Result Codes
When you execute or try to execute an AT command, your modem sends a result
code to let you know whether the command was executed. An OK result code
means the AT command you sent was executed. If you receive an ERROR code, it
means the command was invalid.
The Omni 288S also provides result codes that show:
Whether or not a Dial Tone was detected when the modem originated a call.
If a busy signal was detected when the modem originated a call.
If a remote telephone ring was detected when dialing.
The speed, protocol, and error control / data compression method used.
If your modem has detected an incoming ring.
Result codes can originate from any of eight result code sets. The ATXn
command lets you choose which set of result codes your modem uses. By default,
your modem uses result codes equivalent to the ATX5 command.
The result code options will be covered more thoroughly in later chapters.
Viewing S Register Values
Status registers (or "S-registers") contain values that determine the modem’s
operating characteristics. Whenever you send an AT command to your modem,
you are actually changing the value of an S-register.
You can use the Sr? command to view the value of S-register ‘r’. For example,
to view the value of S-register S0, which controls auto-answering, type ATS0?
and press Enter. The modem responds with a three-digit character showing the
value of this register, followed by OK. A value of 002, for example, means your
modem will auto-answer incoming calls after the second ring.
Some S-registers are bit mapped. For these registers, you can use the Sr.b?
command to read their values.
