Testing your modem connection

Follow these steps to test whether you can send commands to your modem:

1. Log in as root.

2. Add a ``Direct'' line entry for your modem to the /usr/lib/uucp/Devices file if one does not already exist. You can specify either the modem or the non-modem control device for the port to which the modem is attached. For example, the following Devices entry is for a modem connected to a single port on COM1:

   Direct	tty1A - 9600 direct
   

3. Establish a direct connection to the modem so that you can send commands to it. This connection uses the ``Direct'' line in the Devices file. For example, if the modem is connected to a single port on COM1, enter the following command:
   
   cu -ltty1A dir

   You should see a message such as OK (AT-compatible modems) or 0 to indicate that the modem is ready to accept commands.

   If you see the message cu: dir permission denied, you do not have write permission on the /usr/lib/uucp/Devices file. Set the correct ownership and permissions using the commands:
   
   chown uucp:uucp /usr/lib/uucp/Devices
   chmod 644 /usr/lib/uucp/Devices

   If you do not see a message indicating that the modem is ready to accept commands:

   • Check that you entered the cu command correctly.

   • Ensure the ``Direct'' entry in the Devices file is correct.

   • Use the hwconfig command to check that the serial port is configured.

   • Use the l command to check that the device files associated with the port (such as /dev/tty1a and /dev/tty1A) have owner and group both set to uucp. If not, change these using the commands:
     
     chown uucp:uucp /dev/tty1a
     chown uucp:uucp /dev/tty1A

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   NOTE: The instructions that follow assume an AT-compatible command set and response codes. Other modems may use other conventions. Consult your modem documentation for further details. The instructions are illustrated by ``Testing a modem connection''.

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   Testing a modem connection

4. If you see a message from the modem indicating that it is ready to accept commands, enter AT. An AT-compatible modem should return OK. If you have set the modem to return numeric result codes rather than text, you see 0. If you do see OK, your modem is ready to dial out.

5. Check that the ``Send Data'' light on the modem flashes when you press a key. This indicates the modem is receiving signals from the computer. If this light is not flashing, check your cable and modem switch settings. If the ``Send Data'' light flashes, but you still do not get an OK response from the modem, enable the modem's echo capability and responses to commands by entering ATE1Q0

   If your terminal still does not display OK or 0, connect the modem to another port (COM1 or COM2). If the modem works with the new port, check that the device is using the correct interrupt vector. (Serial port COM1 uses interrupt 4; COM2 uses interrupt 3.)

   If the terminal does not echo the OK message when it is connected to the new port, check your cable again. You can also connect a terminal to the port (with a proper terminal cable) and verify that the port works. If the modem returns garbage, then try connecting at different speeds; some modems can be set to communicate at the DTE connect speed, while others communicate at a fixed speed. If the modem still does not respond properly, the modem may be defective.