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LB-499-GSM Data Transmission Module

LB-499-GSM Data Transmission Module

Applications

The GSM/GPRS (LB-499-GSM) data radio transmission module enables remote data transmission to the LBX software via the GSM/GPRS mobile network.

The module may be connected to the following devices:

  • LB-480 — data recorder;
  • LB-490 — data recorder/weather station.

IP address

There are 2 ways to establish a connection between the LBX and the LB-480/LB-490 recorder, depending on how the IP addresses are assigned by the mobile network operator. By default, in most cases the operator assigns a private IP address within the operator’s network. There are, however, ways to obtain a public address, as part of a certain operator’s service.

Permanent, public IP address

The easiest method of establishing a connection is when the network node is assigned a permanent, public IP address by the mobile network operator. This is not a standard procedure; it requires special, “by request” configuration by the operator (usually charged additionally).

In such a case the LB-480/LB-490 recorder has a permanent known address, and any authorised LBX software may establish a direct connection.

Private IP address

In a typical case, the mobile network operator provides the devices connecting with the network via the GPRS modem with private addresses. In order to enable the data transmission with other nodes on the Internet, such an address is subject to a translation mechanism (NAT).

For network nodes that are to perform a client role only (connecting with others) this is a solution that gives the possibility of connection (e.g. a phone and a web browser).

However, for the nodes that are to function as servers, and the connection is to be established with them, such a solution does not allow an appropriate connection to be made. The node’s address is unknown (assigned temporarily), and even when it is established, it is usually assigned from a range of private addresses and access to it is restricted by the NAT gate from the mobile network operator’s side.

In order to enable data transmission in such cases, the party initiating the connection should be the node operating in the mobile network. The LB-480/LB-490 features such a functionality — with the correct configuration completed, the module connects with the LBX software as required.

The same case applies, when the recorder is connected with the network over a cable (without a modem), but for different reasons it does not have a permanent, public IP address.

Connection with the LBX software

Permanent, public IP address

In such a case, the LBX software establishes a direct connection with the LB-480/LB-490 recorder:

LB-480/LB-490 — direct connection between the LBX software and the LB-480/LB-490

Publically inaccessible IP address

When an address is publically inaccessible, the connection between the LB-480/LB-490 recorder and the LBX software may be established in two ways:

Initiating communication with the LBX software from the LB-480/LB-490 recorder

The LBX software must operate continuously, on a computer with a permanent, public IP address (or properly re-directed from a gate, with the use of mechanisms of port and address re-direction).

A suitable IP address and LBX software port number should be programmed in the LB-480/LB-490 recorder. The LBX software will be configured to monitor the incoming connections.

LB-480/LB-490 — direct connection between the LB-480/LB-490 and the LBX software

When the correct configuration is completed, the LB-480/LB-490 recorder connects with the set LBX software and enables data transmission.

Proxy connection

In the event that the LBX software may not be run with the configuration for connection reception, it is possible to use a proxy. A proxy is an additional server that mediates in the data transmission between the LB-480/LB-490 recorder and the LBX software.

LB-480/LB-490 — intermediary connection of the LBX with the LB-480/LB-490 via proxy

With such a configuration, the LB-480/LB-490 recorder establishes a connection with a continuously operating proxy. The connection is maintained continuously. The LBX software, when attempting to connect with the LB-480/LB-490 recorder, also connects with the proxy, where it pairs the connection of the LBX software with the LB-480/LB-490 recorder and enables data transmission.

The proxy is a software operating on the LAB-EL server.

Sending a text message

Besides the data transmission, the GSM module also enables the sending of text messages. A text message may be sent as a response to the occurrence of an alarm programmed in the LB-480/LB-490.

Text messages may also be sent in parallel and independently from the data transmission performed by the LBX software.