Specifications

Chapter 4 Connecting with Direct Dial
Configuring Direct Dial on the JACE-4/5
Niagara Release 2.3
Niagara Networking & Connectivity Guide Revised: May 22, 2002
4–9
In addition to the initialization string, the functions described in Table 4-2 are other
necessary parameters that need to be set on each modem. On the Sportster, these are
controlled by dip switches. These parameters can be set on other modems using dip
switches or within the initialization string.
For proper operation of your modem with our hardware, you must provide
functionality in your initialization string equivalent to the settings referenced in the
two tables above.
About the AT Command Set
The AT command set is industry-standard command language used to communicate
with the modem. Sometimes this is referred to as the Hayes command set, because
Hayes Microcomputer Products, Inc. developed the original language. The original
command set included about 15 commands, but modern modems can support more
than 250. Commands include configuring features such as data compression,
diagnostics, and flow control. Manufacturers often make up their own commands for
newer features. These commands are then specific to each manufacturer, so modem
initialization strings need to be customized for the modem you are using.
The AT (attention modem) command is followed by one or more commands in the
following formats:
Basic Command Set—a capital character followed by a digit. For example, E0.
Extended Command Set—an ampersand (&) and a capital character followed by
a digit. For example, &A1. Note that A1 is different from &A1.
Note For either set, if the capital letter in the command is not followed by a number, the
number implied is 0. For example, ATE is equivalent to ATE0. AT&A is equivalent
to AT&A0.
Register Commands—Commands are in the form Sr=n where
r is the number of
the register to be changed and n is the new value that is being assigned. The
S-registers are used to set various timing parameters and to redefine selected ASCII
characters and other configuration options. For example, S0=0 disables auto answer
on the modem.
Table 4-2 US Robotics Sportster additional settings.
Function
Sportster
Dip Switch
1
Equivalent AT
Command Description
Display result
codes
3 (on) no equivalent Enables result codes to display to our
hardware.
Auto answer 5 (on) S0=0 Turns the modem’s auto answer function to
OFF. Auto answer is not required because the
JACE picks up the phone when the call comes
in.
Smart mode 8 (on) no equivalent Enables recognition of AT command set.
1. Dip switches in the on position are flipped down.