Testing connections using a modem

You should make sure that the communication between the remote modem and the modem at the control center is working correctly before you configure a modem connection.

Follow these steps to set up a dial-in connection using a modem:

1. Configure the control-center modem to work correctly within your telephone environment.
2. Check the correct operation of the modem by running a simple terminal program on the COM port the modem is connected to. You should be able to enter AT commands and get correct OK replies from the modem.
3. At the remote site, repeat Step 2 with the remote modem.
4. From the control center, call up the remote modem and make sure that the connection is established correctly, when the remote site accepts the incoming call with command ATA. You should see keyboard inputs correctly on both terminal programs. If not, you probably have different baud rates configured on the three lines remote-computer to its modem, modem to modem, center modem to center computer.
5. If that works correctly, configure the remote modem to automatically accept incoming calls, attach the receiver device at the remote site to it, and configure the receiver to send out the NMEA record GGA every second. Try to call the modem again. You should now receive the GGA record at the control center nicely readable. If the modem now does not accept incoming calls from the control center, set the modem to dumb mode (that means it does not try to interpret incoming data from the receiver as AT commands).
6. Now that the communication works correctly, you can replace the terminal program at the control center by Trimble 4D Control Server and configure the modem connection.