Sierra Wireless WISMO218 User Manual download pdf (Page 47)

WA_DEV_W228_UGD_002 Rev 003 Page 47 of 78

WISMO228 TCP/IP AT Commands

Manual

The schematic above explains how [DLE] characters  which have a special meaning in the firmware 

are handled on the WISMO

On the transmitting side, when a [DLE] is not escaped (use case: Desktop PC1 sends data towards the

WISMO

. Data contains a non escaped [DLE] ( no [DLE][DLE] sequence), then the [DLE] is not

transmitted.

On the transmitting side, when a [DLE] is escaped (use case: Desktop PC1 sends data towards the

WISMO

. Data contains an escaped [DLE] ( [DLE][DLE] sequence), then the [DLE] data is

transmitted.

On the receiving side (use case: when Desktop PC2 sends data towards the WISMO

. Data contains

an escaped [DLE]), the data sent from the WISMO

to Desktop PC1 will contain an escaped [DLE]

preceding the [DLE] character (Desktop PC1 receives the [DLE][DLE] character from the WISMO

The scenario is the same for both TCP and UDP sockets.

Protocol

UART

IP Network (active socket)

UDP

Data containing a [DLE][DLE] sequence.

Data containing [DLE].

UDP

[DLE] alone.

A single [DLE] is ignored.

TCP

Data containing a [DLE][DLE] sequence.

Data containing [DLE].

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Sierra Wireless WISMO218 User Manual Page 47