Select the correct GSM band – AT#BND

I just got my second Telit GSM862 Quad module and I could not get it to work. I could use various AT commands to find out various configurations of the system, but I could not send an SMS message or make a call. Well after going though the entire AT command manual and comparing the configuration of my first module versus the second module, I found out that the reason my new module was not working was that it was factory set to use band 0 (900MHz + DCS 1800MHz) instead of band 1 (900MHz + PCS 1900MHz), after setting the module to use band 1 — AT#BND=1 — the module starting working fine. Clearly, band 1 is the correct setting for US.

But why didn’t the module automatically pick the correct band? After all there is the AT#AUTOBND=1 command that is suppose to pick the correct band. The factory default is to disable automatic band selection. I suspect that the automatic selection consume more power and that is the reason why it is by default turned off.

18 Responses to “Select the correct GSM band – AT#BND”

  1. Achilleas Says:

    I have a question. How do you set the correct band? I have the exact same problem and I do not know how to send the AT#BND instruction to my Telit module.

    Please help! 🙂 I am one step behind you 🙂

    • sj Says:

      Hi, Telit US recommends that we use AT#BND=3. In the Bay Area, AT#BND=1 also works fine. That is what I’ve been using. You should do this at the start of your modem initialization. The BND setting is maintained even after power off. So you only really need to do it once, but it is easier to do it each time you power on the modem as part of your initialization.

  2. Achilleas Says:

    I am a newbie. I don’t know how to communicate with my device. I want to open a terminal where I could put all these instructions in. I have no clue how to do that. Any help? 😦

  3. sj Says:

    Hey you said that you’re one step behind me -)

    First you’ll need an evaluation board. Sparkfun sells one, and so does Telit. THe modem can require up to 2 Amp of current (on 850 MHz band) and up to 1 Amp on other bands. I’ve no idea how the Sparkfun evaluation works via USB, but in most cases it does, since if you’re in a reasonable cell coverage area, the Telit will register with less than 150 mA of current. On the PC you’ll need to connect to the evaluation board to HyperTerminal or something like that. I use the Mac, and here are the Mac instructions.

    If you’ don’t have an evaluation board, then you’ll need to build the circuit to control it from the micor-controller. That is a lot more work. It is best to start with an evaluation board.

  4. Achilleas Says:

    First of all I would like to say thank you for all your help 🙂

    Well I have tried the Mac instructions. I have compulab’s EM-270X and it has a serial port. I use Kermit to connect to the terminal inside the linux distribution (Angstrom) of the board.

    I installed the drivers for my USB to serial device and I know it works because I can log onto the board. The board has a Telit chip on it.

    My device is /dev/tty.KeySerial1 and that’s what works with kermit. There’s another one called tty.SerialPort-1 but I haven’t used it. But that will connect me to the whole device and not the modem. Should I first connect to the device and then from there try and follow the mac instructions? I am confused! 😦 It’s been so many days I have been trying everything. Any suggestions?

    • sj Says:

      Make sure that you’ve the virtual USB driver. I think you need an Intel based Mac. Do you use an Arduino module? Can you upload programs to the module?

  5. Achilleas Says:

    could I just do echo “AT#BND=3” > /dev/ttyS2 ?

    Also how do I know for sure if it’s /dev/ttyS2? I just noticed that from an other script.

  6. Achilleas Says:

    * Correction: Do the echo command through the device’s terminal.

    It’s the Compulab EM-X270 and it has the Telit module.

  7. sj Says:

    What is the value of the AT Command Echo on your system? During development, it will be easier to use ATE1. Are you sure you’ve installed the virtual USB driver from Atmel? If you’ve and you connect a USB device to your computer then you should see a USB device with a name like: /dev/tty.usbserial-A80081EF. Use the UNIX screen command to connect to this device, e.g., screen /dev/tty.usbserial-A80081EF 2400 (where 2400 is the baud rate).

  8. Achilleas Says:

    The whole board is connected to my Mac using a Keyspan USB Serial adapter. I installed the software and I see tty.KeySerial1 as the device. I use Kermit to connect to the board. Kermit brings up the shell for the Angstrom Linux that is installed on the board and I can log in as root.

    The board includes the Telit module but I don’t know how to directly access it. The manual says “The cellular module is interfaced to the PXA270 processor via the BT_UART.”

    Once I am on the shell I can type commands and I can use vi to edit files. There’s a USB port so I am assuming that I can install software through a USB thumb drive. In fact that’s how I got the Linux image on the device.

    Why would I install a driver from Atmel? I also tried from my mac to connect to the serial port using e.g: screen /dev/tty.KeySerial1 -A80081EF 2400 but it does not respond to any keyboard input.

    My /etc/gprs-options file looks like this:

    connect “/usr/sbin/chat -v -f /etc/ppp/gprs-connect”
    disconnect “/usr/sbin/chat -v -f /etc/ppp/gprs-disconnect”

    So I assume that the Telit is ttyS1. Another thing I did is I went tot he gprs-connect file and added the “AT#BND=3” in there and turned the gprs on and off assuming that this would throw the command in there. Nothing happened.

    Any ideas?

  9. Achilleas Says:

    So I found out that if I log in to the development board (get the terminal etc) I have to kill 2 processes: (1) gsmd and (2) phone-kit.

    Then I tried to do:

    chat -v -s ” ‘AT#BND=3’ /dev/ttyS1

    And it returns:

    send (AT#BND=3^M)
    expect (/dev/ttyS2)#BND=3

    I also tried:
    chat -v -s ” ‘AT#BND=3’ ‘OK’ /dev/ttyS1

    and it returns:

    send (AT#BND=3^M)
    expect (OK) AT#BND=3

    Any ideas?

  10. sj Says:

    Hi, I’ve not used the Telit development board. I use the sparkfun development board instead. Please note that you’ll need to end each AT command with carriage-return followed by line-feed. Specifically, you need to enter (control-m aka carriage-return)(control-j aka linefeed) instead of ^m^j. In a program you replace ^m^j with \r\n (\r is carriage-return which is ascii 13, and \n is line-feed which is ascii 10. In the terminal you must enter control-m followed by control-j.

  11. Achilleas Says:

    Well I guess the question would be how do you connect to /dev/ttyS1 from any Linux distribution? Which one is the right way?

    I was also told I should use the “screen” command but Angstrom does not have such a command. When I type “screen” it says not found.

  12. sj Says:

    You should be able to use YUM to install screen. I’ve only tried this from a Mac, so not sure what potential issues there are with Linux. I’m assuming that you’ve already installed the Virtual COM Port Driver for Linux.

  13. Diogenes Says:

    Hi SJ, I has the same problem with automatic band selection ( My country is Argentina ). In all my projects, I disable automatic band selection and loop in manual mode for 4 bands loocking for good registration, normaly in my country the Telit only is registered in BAND=1 and BAND=3.

    Sorry for my english 🙂

  14. TAHA Says:

    i want to know the frequency VIA at commands…am using a60 siemens phone for communicating purpose…can anybody help me ? !

  15. Marlene Says:

    This is the reason I love Nice postfs.

  16. gsm aanbiedingen Says:

    gsm aanbiedingen…

    […]Select the correct GSM band – AT#BND « n o t e 1 9 . c o m[…]…

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