RBVND-Lite Troubleshooting

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No connection with the modem

If there is no communication with the modem take the following steps:

  • check all external connections with the modem (serial interfaces, USB, power supply).
  • check that the power supply is correct (see Power supply).
  • check that the COM port is correct.

No connection/communication with the modem

If there is no communication with the modem take the following steps:

  • Check all external connections of the modem (RS-232 or USB, Power supply)
  • Verify if the power supply is correct (see Power supply)
  • Check if the COM port is correctly parametrized


Receiving ERROR message The modem answers ERROR on AT command in the following cases:

  • The syntax of typed AT commands is incorrect – check the command syntax in [1]
  • Parameters of typed AT command are incorrect - type AT+CMEE=1 for enabling wide description of error which occurred. The response now will be in format:

ERROR +CME ERROR: <err> where <err> is a description of the error which has occurred.

Receiving NO CARRIER message There are some common cases when the modem answers NO CARRIER:

  • If a data/voice/fax connection cannot be established
  • Right after hanging up the data/voice/fax connection
  • If there is no connection with the network – check antenna and registration status (see Network registration)
  • If there is no power supply (see Power supply)
  • If modem answers NO CARRIER, you can check extended error code using AT#CEERNET command. A list of codes can be found in AT commands reference guide manual.