Technical information

SerialNET Theory of Operation
2-90 AT+i Commands Reference Manual May 31, 2008
In this mode, data is retrieved from the remote side as it is made available. TELNET options
embedded in the server/client response stream are stripped by W24 before being turned over to
the host. TELNET specifies many operational options. W24 restricts its operation mode to the
minimum implementation to assure best inter-system compatibility.
Following are the TELNET options negotiated by W24. Any other options negotiated by the
remote side are rejected by W24.
Notes:
• In SerialNET over TELNET mode, a BREAK signal that is detected on the host
USART is relayed to the remote side and no reset is performed.
• If the host interface is USART1, then DSR signal changes are not detected.
RFC2217 Implementation
The RFC2217 implementation in SerialNET over TELNET mode is designed to:
• Add the ability for a remote client that connects to W24 to send COM port configuration
information to the host device connected to the Internet via W24's TELNET server. The
configuration changes take effect immediately, but are not preserved over software or
hardware reset. The allowed configurations are the same ones available by the SNSI
parameter.
• Add the ability for the host device to inform the remote side about signal changes in CTS and
DSR.
• Add the ability for the remote side to change the value of the RTS and DTR signals of the
host device.
• Add the ability to exchange BREAK signal indications between the host device and the
remote side.
The table below lists the RFC2217 options and sub-options supported by W24. Note that W24
does not send any replies to commands or command values not supported. For more information
about RFC2217, refer to the RFC2217 protocol document.
Option ID Name Value RFC
1 echo OFF 857
3 suppress go ahead suppress 858
24 terminal type VT100 1091
31 window size whatever 1073
44 com port partial implementation 2217