Common Initial Issues

  1. Device not visible: The devices are shipped in hibernate mode and are not discoverable. Connect to the USB cable and charge the device, on disconnecting the device will be discoverable.

  2. Cannot pair with device: There may be an active connection already formed that was not closed during device discovery. Briefly connect to USB and disconnect again to reset the device; then retry. For LE pairing issues, see the LE communication section.

  3. Cannot open a COM port: Firstly, view the device using the OS (e.g. device manager) to confirm that the OS has successfully installed the device and designated it a COM port number. Select the assigned COM port number using the terminal program and then connect. If this fails, try another terminal program; some terminal programs are not compatible with RFCOMM; try teraterm, a free open source terminal project.

  4. No response from device: For some OSs, the device may have formed more than one COM port for the device to expose the RFCOMM control channel; the data channel is usually port with the lower number. Also, check the behaviour of the return key for the terminal used; it may send a line feed (< LF>) instead of < CR>.