Technical information

Improved OEM Features
1-10 AT Commands Reference Manual August 5, 2008
• Up to four simultaneous protocol connections.
• Ability to pass data via the protocol stack using AT commands (command mode). This
relieves the terminal from switching the RS232 to "binary mode" and back to "command
mode".
• Ability to use UDP and TCP simultaneously.
• No need for protocol support from the terminal - only data sending and receiving.
• Reduced memory utilization. The G24 manages the protocol stack and therefore saves
terminal memory.
• Ability to open TCP connections, secured with SSL/TLS.
• Ability to receive the incoming TCP connections.
• Ability to accept IP connections only if the IP belongs to a defined IP white list.
Technical Description
Figure 1-1, “System Overview,” on page 1-5 displays the system overview which comprises the
following links and layers:
Physical layer links:
• The terminal is connected to the G24 using a physical RS-232 connection.
• The G24 is connected to the GGSN using a GPRS link.
• The GGSN is connected to the Internet via some sort of physical connection (usually
telephone or cable).
Point-to-point layer links:
• AT command protocol is used to transfer data between the terminal and the G24.
• After authentication, the G24 is linked to the GGSN using PPP protocol.
• The GGSN is connected to its Internet service provider using some protocol.
TCP / UDP layer:
• The G24 can transfer data with the WEB using either TCP/IP or UDP/IP protocols.
• The protocol stacks in the terminal or in the OEM must be managed when using TCP/IP or
UDP/IP protocols. The G24 software can manage these stacks internally. This enables the
G24 to relieve the terminal from the job of managing these protocols.
Note: Currently, the embedded TCP/IP feature may be used only for mobile-initiated
connections. The embedded. TCP/IP feature cannot listen on a port for incoming
connections.
FTP Connection
Overview
G24 implements FTP connection feature, based on RFC959 standard, and operates as a FTP
client. When connected to a remote FTP server, G24 is able to receive information about remote
file system, manage it and perform files transfer operations.