Wavecom GSM modem over TCP/IP
Connecting a GSM modem directly to a server is not always convenient and sometimes not even possible. In those situations a GSM modem with TCP/IP network support or a separate TCP/IP converter is a good alternative.
In this review I test a cost effective RS232 to TCP/IP converter, the ATC-1000, with a well known legacy GSM modem, the Wavecom Fastrack Supreme GSM modem.
|Wavecom Fastrack Supreme specifications|
|GSM Frequency bands||850, 900, 1800, 1900|
|Network protocols||GSM, GPRS|
The ATC-1000 is an industrial RS232 to TCP/IP converter with a serial port, an RJ45 network port and a connection for an external power supply. The device can be set up from a browser but since its default configuration is a static IP address it is necessary to use a computer with a specific IP range to connect to the device for the first time. This is described clearly in the manual and using the web interface the ATC-1000 can easily be set up to use DHCP. The PC software included with the ATC-1000 is rather limited. It does offer a virtual COM port driver for Windows but it is a normal Windows program instead of a device driver or service and can therefore not be used when no one is logged in to the computer. Don't bother to install it when you only want to use the device with Diafaan SMS Server.
The rest of the setup is straightforward, since the Wavecom Supreme uses a fixed baudrate of 115200 baud this baudrate is set in the ATC-1000. The Telnet protocol is set to Server on port 23 so we can connect to the device from a remote computer with Diafaan SMS Server.The Wavecom Fastrack Supreme
The Wavecom Fastrack Supreme (now replaced by the Sierra Wireless Fastrack Xtend) is a GSM modem with a serial port, an external antenna connection and an external power supply. Like any serial port GSM modem, setting the device up is easy. Just connect the antenna, power supply and insert the SIM card. An often overlooked part of the Fastrack Supreme is the small black slider in front of the SIM card slot that locks the SIM card. Without this lock the modem does not load the SIM card. The Fastrack Supreme is connected to the ATC-1000 with a normal 9-pin serial port cable.
Add the TCP/IP modem to Diafaan SMS Server
Since the GSM modem could be located literally on the other side of the world, it is not possible to use the Search button to let the GSM Modem Gateway the modem automatically. Instead, the TCP/IP connection is selected from the GSM modem port list and the Host name/IP number and port number of the ATC-1000 is entered manually.
The Test button confirms that the ATC-1000 is set up at the entered IP number and port and that the Wavecom Fastrack Supreme is found and connected to the mobile network.
To increase the reliability of the modem, you can set the "RebootBeforeInitialization" option to "True" in the advanced properties of the GSM modem Gateway after the initial setup. This option instructs Diafaan SMS Server to send a full modem reboot command to the modem whenever a problem occurs and prevents lock ups of the modem.
In daily use, the combination of the ATC-1000 and the Wavecom Fastrack Supreme performed just as reliable as if the modem was connected to a local serial port. After a network disruption, the connection with the modem recovers automatically when the network is available again.
SMS send speed
|Time to send 500 messages of 160 characters, delivery confirmation enabled. All messages sent to the same number (concurrent send and receive)||49 minutes 50 seconds|
Using a serial GSM modem over a TCP/IP connection is a very good alternative to a USB or serial modem. Especially when it is difficult to use a GSM modem in the data center, a TCP/IP connection makes it possible to place the modem on a location with better network coverage. When using multiple GSM modems, the modems can be placed in different spots to prevent interference between the modems or overloading a specific network cell.