User's Guide

The Operational View SB300 Series
Page 22 Proprietary and Confidential 2110059 Rev 1.0
4.2.3. Conditions
In addition to mode and state the modem can be in one of two conditions:
• On-line – actively connected to a remote terminal or with an active session in CDPD.
• Off-line – disconnected from any remote terminal or without an active session in CDPD.
While in off-line condition the modem can only be in command state.
In the on-line condition, the modem can be:
• In data state which passes data through the modem between the host (DTE) and the remote
terminal.
• In command state which exchanges data between the host (DTE) and the modem (DCE)
without passing it through the active connection to the remote terminal.
4.3. Modem Communications with the Host (DTE)
Communication between the host (DTE) and the Sierra Wireless SB300 Series modems is
currently fixed at:
bps: 19200
Data Bits: 8
Parity: None
Stop Bits: 1
Any application being used to issue AT commands must be configured this way.
Local flow control is implemented in hardware (RTS / CTS).
Autobaud support will be implemented in a later firmware release by April 1999 or earlier.
4.3.1. DTE Communication Options
As shipped the modem is configured with these settings:
• Echo enabled (E1) which causes the modem to echo characters received from the host back to
it while in command state. The backspace is echoed as <backspace> <space> <backspace>.
• Quiet result codes disabled (Q0) which enables the modem to issue result codes following
commands.
• Verbose result codes (V1) provide results in English text appended with <CR><LF>.
• SB320 Speaker Control is set to be on until carrier detected (M1).
This setting means that a host running a terminal emulation program for communication with the
modem should have this configuration:
• Emulation – TTY
• ASCII character
Sending:
• No line ends with line feeds
• No local character echo
Receiving:
• Do not append line feeds to incoming line ends
• Do not force incoming data to 7-bit.
• Wrap lines if necessary
Commands may be entered in upper or lower case.
4.3.2. DTR Signal Handling
The modem can be configured to handle the DTR signal from the host in several ways. The AT
command &D sets the method. The factory default is to hang up any remote connection and enter
command state with auto-answer disabled (&D2).