Sierra Wireless WISMO218 User Manual download pdf (Page 44)

WA_DEV_W228_UGD_002 Rev 003 Page 44 of 78

WISMO228 TCP/IP AT Commands

Manual

UDP Sockets in Continuous Mode

UDP is a connectionless protocol and hence there is no way to detect or cause a shutdown. However,

an [ETX] character is used to mark the boundaries of datagrams.

All data written on a UDP socket is collected till an [ETX] character is encountered or the maximum

size of the datagram

is reached and will be sent as a single datagram. Similarly when reading data,

all data will be read till an [ETX] character is encountered which indicates the end of the datagram.

Note that, in this mode, packet segmentation feature is not supported.

In case an [ETX]/[DLE] character needs to be transmitted, it should be preceded by a [DLE] character

similar to the TCP socket.

When the UART leaves DATA mode, either because of a 

AT+WIPDATA=1, index, 0 on another UART, the currently unsent data is sent as a single datagram.

The maximum size of a UDP datagram has been fixed to 5182 Bytes. This limit is an arbitrary one. Note that when the UDP

datagram sent is bigger than 5182 Bytes, the whole datagram will be discarded by the WISMO228 module.

Also note that the smaller the datagram is, the more certain it will reach the aimed destination. UDP is a non-reliable transport

layer.

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Sierra Wireless WISMO218 User Manual Page 44