Bekijk de volledige versie : How to send AT commands to the modem

29-03-2008, 08:03
There is lots of stuff you can do with AT commands with a 3G modem. One important command is AT+CSQ that shows the radio signal level. Very useful e.g. when adjusting directional antenna. WL-500 does not have means for monitoring modem signal level as such, so we need AT commands.

An easy way, and supported by very basic Linuxes is to use just echo and cat. Here is how to do it:

1. Open two terminal windows to your WL-500.

2. In one window start capturing the modem port with cat:

cat /dev/usb/tts/1
3. In the other one send commands to the modem with echo, e.g:

echo at+csq > /dev/usb/tts/1

I have tested this OK with Huawei E220, but for some reason ZadaCOM 3G+ (Sierra Wireless) did not send any response to the screen.

Huawei has very restricted selection of commands, but e.g. in ZadaCOM there is a lot you can do in addition to monitoring antenna signal: for example you can send SMS's, select the 3G or 2G band or even check the modem temperature and so on.

Here is a good document about AT commands supported by Sierra: http://siptune.net/downloads/sierra-at-commands.pdf

BTW, you can use these commands also with modem connected directly to the PC, e.g with Putty or Hyperterminal.