Specifications

Niagara Release 2.3
Revised: May 22, 2002 Niagara Networking & Connectivity Guide
Chapter 4 Connecting with Direct Dial
Configuring Direct Dial on the JACE-4/5
4–8
ones that implement the AT command set in the same way (see the next section
“About the AT Command Set”). You would need to provide the correct initialization
string for any non-listed modem.
For example, this is the initialization string we use for the US Robotics Sportster:
AT&F1E0&A1X4
A breakout of the parameters set in this string is listed in Table 4-1.
Table 4-1 US Robotics Sportster initialization string.
Parameter Description
AT The prefix used to tell the modem that one or more commands follow.
&F1 Use the hardware control flow template. This template sets the modem to
hardware flow control, a fixed serial port rate, the highest level result codes,
and the most complete result-code set.
E0 Sets the command mode echo to off. The modem does not display keyboard
commands.
&A1 These settings enable ARQ error codes, which allows the modem to detect
flawed data and retransmit it. It also returns connection rates to the modem
as follows:
10/CONNECT 2400—Connection at reported rate. Other valid options
include 18/CONNECT 4800, 13/9600, 20/7200, 21/12000, 25/14400,
43/16800, 85/19200, 91/21600, 99/24000, 103/26400, 107/28800.
X4 Sets the result codes that are returned from the modem to our hardware as
follows:
• 0/OK—Command has been executed.
• 1/CONNECT—Connection established with another modem
• 2/RING—Incoming ring detected.
• 3/NO CARRIER—Carrier may not be detected or carrier has been dropped
due to disconnect.
• 4/ERROR—Command is invalid.
• 5/CONNECT 1200—Connection established with another modem at 1200
bps.
• 6/NO DIAL TONE—Dial tone not detected during the normal 2 seconds, set
in Register S6.
• 7/BUSY—Busy signal detected; modem hangs up.
• 8/NO ANSWER—After waiting 5 seconds for an answer, the modem hangs
up; returned instead of NO CARRIER when the @ dialing option is used.
X4, continued In addition, the X4 setting enables the following functions on the Sportster
modem.
• Adaptive Dialing (HUNT)—The modem attempts to use tone dialing, and if
that doesn't work, it reverts to rotary (pulse) dialing.
• Wait for Another Dial Tone (W)—The modem halts dialing until it detects
another dial tone.
• Wait for an Answer (@)—The modem does not continue dialing until it
detects 5 seconds of silence on the line.
• Fast Dial—The modem dials immediately after detecting a dial-tone,
instead of waiting the normal 2 seconds set in register S6.