Sierra Wireless DART 200, Руководство пользователя

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DART 200 CDPD Modem User’s Guide 1 Introduction
Sierra Wireless, Inc. 1-4
3. Data packets are routed by the MDIS through the appropriate
network to the Fixed End System (F-ES), usually a host computer
over a public or private data network.
4. If a response is required from the F-ES, the process is reversed.
The role of the DART 200 in the CDPD network is to:
1. Accept commands and digital data from the end-user application
equipment through the RS-232 port.
2. Assemble the data into packets.
3. Encrypt the packets.
4. Transmit the encrypted data packet to the network.
The DART 200 also:
1. Receives packet data from the network.
2. Decrypts the packets.
3. Disassembles the packets to extract the application data.
4. Passes the serial data to the end-user’s application equipment
through the RS-232 port.
Airlink security, to prevent eavesdropping, is provided by encrypting the
data packets between the DART 200 and the MDIS. If end-to-end data
security is desired it must be implemented or otherwise provided by the
end-user.
The major cellular carriers and equipment manufacturers created a trade
group called the Wireless Data Forum (formerly the CDPD Forum), that
develops and publishes the governing technical specifications for, and
promotes the use of CDPD technology.
AT command set summary
The Basic and Service Provider AT command sets are listed in Tables
1-1 and 1-2 (pp. 1-5 and 1-6). The AT commands can be concatenated
(end-to-end or with a blank between commands) for up to a length of 80
characters including blanks, for example:
•
Normal command concatenation
•
ATE1V1&D0&S1\F3\N2
•
AT\S?S57?&V+
•
White space concatenation (for readability)
•
AT E1 V1 &D0 &S1 \F3 \N2
? ?
NOTE:
Either the M-ES or
F-ES can initiate
CDPD communication.