Airlink Raven GPRS - Manual (Page 38)

Host Modes
30 Cingular GPRS Raven User Guide Version 2.01
UDP Pad Mode
When the modem is in UDP PAD (Packet Assembly and Disassembly) Mode, all
characters received on the serial port are assembled into UDP packets and sent to
the Raven’s remote IP address/port, and any packets received from the same IP/
port-destined for the Raven’s Device Port (see *DPORT)--are disassembled and
dumped onto the serial line.
A UDP session is initiated by one of the following events:
• Using the Dial UDP (DP) AT command (ex. ATDP192.168.3.23/3456)
• Setting the Startup Mode Default (MD) to 3 (UDP) so that a UDP session is
entered automatically when the modem powers up. Serial data will be sent to
the IP/port specified in S53.
• An incoming UDP packet is received and
• UDP auto answer is enabled (S82=2)
• The destination IP address matches that in S53
• Or allow any IP is set (AIP=1)
• The modem is in AT mode [not in a current UDP or TCP session]
UDP packet assembly is affected by the values of S50 (PAD Forwarding Time-out)
and S51 (PAD Forwarding Character). Data received in the serial buffer will be
transmitted when the idle inter-character time-out specified in S50 (in tenths of sec-
onds) occurs or when a character is received that matches S51 (if non-zero).
UDP Auto Answer
UDP auto answer (previously called UDP half-open) is set with S82=2. When set,
the Raven will automatically establish a UDP session to the source IP address and
port of the UDP packet received. The Raven will remain "locked" to this one
remote IP/port until no data is sent or received for the time interval defined in the
UDP auto answer time-out (S83). During this session, packets from other IP/port
addresses will be rejected, unless *UALL is set. Whether or not an incoming
packet will cause the modem to enter a UDP session is always dependent on the
S53 and AIP settings.
When idle, after the time-out has occurred, the Raven is in AT command mode on
the serial port, and any valid AT command may be entered during this time.
The Normal UDP Mode (MD3) can be combined with UDP auto answer to cause
the incoming serial data to be sent in UDP packets (instead of being treated as AT