TECHNICAL MANUAL
Telit GM862-GPS
Quad Band GPS Data Terminal Module
Pag.29 of 79
Rev. 0
Note that the connections request are FIRST screened in the firewall, then if they are
accepted they pass to the listening socket; therefore only hosts that are in the ACCEPT
chain rules of the firewall can induce a connection request, the other host requests will be
silently discarded without any indication to the remote host (for security reasons).
Once the connection is received and closed, the socket is not anymore in listen. If the
application needs again to be in listen, then it shall send again the socket listen #SKTL
command.
NOTE: this command differently from the AT#SKTOP DOES NOT automate all the
process of activating the GPRS, if no GPRS is active the command reports ERROR;
therefore before issuing this command the GPRS shall be activated with AT#GPRS=1
command.
In the same manner, when disconnecting the #SKTL command does not close the GPRS
context, leaving it active for next connections until an AT#GPRS=0 command is issued or
the network requests a context closing.
3.10.10
Known
limitations
The implementation of the EASY GPRS feature has the following known limitations:
- Only one socket can be opened at a time, no multiple socket connections can be
made;
- Only one connection request can be accepted at a time, subsequent requests will be
silently discarded.
- Only the first GPRS context is associated with this feature;
- It is taken for granted that external processor will be able to handle at least a limited
v.24 implementation: RTS, CTS and, highly recommended, DCD lines; this because
software flow control is not applicable to the feature;
- Due to the particularity of this feature, the flow control of both the directions uplink and
downlink is interlocked