SV 258 PRO User Manual
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The functionalities that mobile modem offers are:
•
Main communication channel
•
SMS / E-mail alarms
•
SMS command exchange.
4.2.1
Main communication channel
Main communication channel is the TCP connection (a lossless data exchange protocol) that can be used
to exchange commands as specified by Appendix A to SVAN 958A User Manual. + assures this
connection and provides the most accurate and real-time method of performing data download,
performance validation and measurement start/stop.
Main communication channel of SV 258 PRO can be established by one of two available methods: TCP
Client or TCP Server.
The
TCP Client
is a mode of main communication channel in which the mobile modem is configured to
initiate connection to a designated address (
remote host
). Each time a
reconnection period
(default value
is 30 seconds) has elapsed, SV 258 PRO attempts to establish a TCP connection to a designated address
on a designated port (
Data Port
). Should the connection be established successfully, SV 258 PRO can
exchange commands as in TCP Server mode. Should the connection attempt fail or is broken by the
remote
host
, SV 258 PRO will attempt to connect again after another reconnection period has elapsed.
To prevent the connections from going
idle
(a state in which the connection seems active, but no data can
be transferred
– it may happen due to mobile operator terminating the link, but the TCP protocol not being
able to detect it), the station maintains the connection to the server by sending small packages of data at
reconnection period (which by default is one minute). If the transfer is not properly acknowledged by the
other party, the connection will be terminated.
Note: TCP Client mode is used in the SvanNET web-service.
SV 258 PRO uses the TCP Client mode for connection with SvanNET (this is the default setting of SVAN
958A). The user PC connects to SvanNET via a web browser or +, and the service creates a
"bridge" between the station and the user PC. In this case, the user does not need to buy more options for
SIM card (public dynamic or public static IP addresses are typically optionally payed and often hard to
obtain). The essence of SvanNET is to simplify the procedures and requirements necessary for the
connection.
TCP Server
is a mode in which the mobile modem is configured to act as a server for incoming connections.
The modem is waiting for the first connection to be established on a designated port (called
Data Port
;
default 8001). Such connection can come from any application - an initiator of the TCP connection (such
as +) called
remote peer
. This mode is recommended as it gives the initiative to the application.
This mode requires the SIM with a
public address
(also called
public IP
).
The
TCP Server
mode uses a so-called
Registration
. This is a method of translation of a
dynamic
address
to a form of a static credentials. It is essential for effective use of a SIM card with a
dynamic IP
.
The dynamic IP means that the IP address is changed each time the modem establishes connection to the
Internet. The Registration feature allows to use the current internet address by an external application for
the connection.
There are two Registration methods supported by SV 258 PRO:
1. DynDns
2. Address Server
The
DynDns
is a service that allows to translate a static name to the internet address. The special
controlling application uses this name to identify SV 258 PRO in the Internet as an internet address. The
properly configured station provides means to validate its internet address to be recognized in the Internet.
The static name provided by DynDns service is translated by the DNS protocol to a given internet address
to which an application can connect to.
