User's Manual

Table Of Contents
SerialNET Theory of Operation
AT+i Programmer‘s Manual Version 8.32 29-6
29.11.1 Mode of Operation
SerialNET over TELNET mode expands the Auto-Link mode (!SNMD). In this mode,
iChip immediately goes online upon activating SerialNET, regardless of whether serial
data has arrived or not.
If the LPRT (Listening Port) parameter is defined, iChip opens a listening port and awaits
a connection, and so it acts as a TELNET server. If, on the other hand, LPRT is not
defined, but HSRV (Host Server) is defined, iChip acts as a TELNET client and
immediately opens a TELNET socket link to the TELNET server.
Note that, even when configured as a client, iChip still acts as a server in RFC2217. See
the following section ―RFC2217 Implementation‖ – for a more detailed explanation.
The SerialNET over TELNET mode expands iChip‘s TELNET client in the following
aspects:
It allows iChip to operate both as a TELNET server and client.
It partially supports RFC2217.
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 iChip before being
turned over to the host. TELNET specifies many operational options. iChip restricts its
operation mode to the minimum implementation to assure best inter-system
compatibility.
Following are the TELNET options negotiated by iChip. Any other options negotiated by
the remote side are rejected by iChip.
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
Notes:
1. 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.
2. If the host interface is USART1, then DSR signal changes are not detected.
29.11.2 RFC2217 Implementation
The RFC2217 implementation in SerialNET over TELNET mode is designed to:
Add the ability for a remote client that connects to iChip to send COM port
configuration information to the host device connected to the Internet via iChip‘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.