GSM/GPRS modem connects devices to the Internet

Westermo Data Communications has released a new GSM/GPRS modem incorporating an enhanced TCP/IP stack that enables remote devices to be connected to the web

Westermo Data Communications has released a new GSM/GPRS modem incorporating an enhanced TCP/IP stack that enables remote devices to be connected to the web.

Using a fixed public IP address SIM card the GDW-11 modem can provide a direct IP connection to remote devices allowing them to be viewed from anywhere in the world.

For increased security a private IP address can be used.

The GDW-11 is designed for industrial applications and can be used on 900 and 1800MHz GSM networks and offer a Carrier Select Data (CSD) speed of up to 14.4 kbit/s, GPRS speed up to 85.6 kbit/s and serial speed up to 115.2 kbit/s (network dependant).

Traditional telemetry applications have the server polling the outstation.

The GPRS network is designed to work in the opposite direction with the client requesting data from a central server.

To be able to utilise GPRS in such applications the modem has to be able to establish the connection and wait for any data.

The GPRS connection must also be seamless and reliable.

The GDW-11 enhanced TCP/IP stack automatically re-establishes the link should the GPRS connection be broken.

GPRS modems incur costs only when data is transmitted so a remote device can have a permanently active connection at a very low cost.

The modem requires an every day SIM card to provide connection to a network service provider of choice.

The GDW-11 also has the ability to make a data call on the GSM network or send an SMS message when an RS232 signal is activated, allowing the modem to be used in applications where the connected device has no intelligence to initiate a call using AT commands.

If the network uses a PIN number, this can be stored in the modem to ensure the availability of the modem after a power failure.

The modem can also re-register with the network, if this is required, as some networks will de-register a SIM that has not moved or been inactive for a period of time.

The GDW-11 is IP21 rated and has galvanic isolation for the power supply.

It is DIN rail mountable and has an extended working temperature range of -25 degrees C to 50 degrees C, making it ideal for use in both industrial and outdoor applications.

The unit incorporates eight LED indicators, one of which can be used to give a signal strength indication.

It works from an operating voltage of 9.6 - 57.6VDC (polarity protected).

Configuration of the modem is made simple by the accompanying GD-tool software, which also contains a network signal strength tool that gives a value on the relative strengths of the networks in the current location, which aids installation.

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