Chapter 6 – UDP Socket Services
Multi-Tech Systems, Inc. AT Commands for Wireless Modems with IP Connectivity (S000333D)
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#OUDP Open an Active UDP Session
Definition:
Once an IP link is established, and if no other TCP/IP stack resource is active, this command sent by
the attached host directs the TCP/IP stack to initiate an UDP session in active mode on the specified
UDP remote port UDPPORT to the specified remote IP address UDPSERV.
The host can then transmit to the UDPPORT or UDPSERV address. Datagrams can only be received
from this UDPPORT or UDPSERV address.
The host can stop the UDP session by issuing an <ETX> character.
Note:
The TCP/IP stack will only interpret an <ETX> character as a close request if it is not preceded
by a <DLE> character. As a consequence, an <ETX> character must be sent (even in payload data) as
<DLE><ETX>, and <DLE> character as <DLE><DLE>. The attached host must then decode the UDP
socket flow to remove these escape characters.
Values:
Read parameters:
UDPPORT
UDPSERV
UDPTXDELAY
Syntax:
AT#OUDP
Command
Possible Responses
AT#OUDP
Note: Request
opening of
UDP socket
OK_Info_WaitingForData
Notes: This message signals that the UDP socket has been opened. All data from
the attached host / remote UDP peer is immediately transferred by the
TCP/IP stack to the remote UDP peer / attached host.
The attached host may close this UDP session by sending and <ETX>
character.
If an error occurs, the TCP/IP stack issues and <ETX> character on the
serial port before sending the appropriate error message.
AT#OUDP OK_Info_WaitingForData
...
...
...
<ETX>
OK_Info_SocketClosed
OK
Note: The UDP socket is closed.
AT#OUDP
#CME ERROR: 38027
Note: The address of the remote UDP peer has not been resolved by the
secondary DNS server. The TCP/IP stack is not able to reach the primary and
secondary DNS servers or a wrong remote UDP peer address has been filled in.
AT#OUDP
#CME ERROR: <value>
Note: An error has occurred during the UDP session creation. If this error occurs
once the UDP session is effective, it is preceded by an <ETX> character.
#VUDP Display UDP Parameters
Definition:
This command directs the TCP/IP stack to display all the AT# parameters related to the UDP socket
configuration.
Values:
Read parameters:
UDPPORT
UDPSERV
UDPTXDELAY
Syntax:
AT#VUDP
Command
Possible Responses
AT#VUDP
Note: View UDP parameters
#UDPSERV: “”
#UDPPORT: 0
#UDPTXDELAY: 100
OK