User's Manual

Table Of Contents
iChip RAS Server
AT+i Programmer‘s Manual Version 8.32 28-3
iChip defers to PPP negotiation. The (~) is the last character transmitted to the host end to
signal that iChip has taken over the negotiations. Upon this event, iChip continues to
negotiate a PPP connection internally in a manner similar to the procedure that occurs
when iChip picks up the line after receiving <RAR> RING strings. If, however, the first
character received from the calling end after the CONNECT line is not a (~) (0x7E),
iChip remains in Transparent mode, and a regular modem-to-modem data session takes
place.
28.3.2 SerialNET Mode
The RAS can also be enabled while iChip is in SerialNet mode. In this case, however, the
modem RING strings are not forwarded to the host serial port. Once the PPP connection
is established, iChip proceeds to act as it would after receiving a RING event and creating
a PPP connection to a remote RAS server. That is, a listening socket is established on the
LPRT socket, available for a SerialNET connection. This provides an alternative means
to wake-up a SerialNET server device.
28.3.3 Lost Carrier
When iChip is online as a result of a RAS connection and the carrier signal is lost (due to
an error or due to the PPP client closing the connection), iChip checks if the host used the
PPP connection (tried to open an Internet session) during the connection. If the host did
not use the connection, or iChip was in SerialNET mode, iChip silently performs a
software reset and no indication of the disconnection is given to the host. Otherwise, if
the host did use the connection, iChip acts as if this is a regular session created by the
host that was terminated with a lost carrier signal. The error code is returned to the host
on the next command that requires the use of the connection and only then will a software
reset be performed.
28.3.4 Restrictions
Modem RING strings are not detected while the baud rate between iChip and the host is
not yet established. This means that in order to use the RAS feature, one of the following
must apply:
BDRF is set to a fixed value (3-9 or h).
iChip is in SerialNET mode with its baud rate defined by the SNSI parameter.
An a or A was previously received from the host serial port and iChip has determined
the host‘s baud rate.
In addition, Modem RING strings are not detected when iChip is in Modem Command
(MCM) mode.