Cannot read QLowEnergyCharacteristic value after first service discover

QLowEnergyService does not permit the direct read of characteritistic values. Value changes can only be discovered via notification/indication, after value writes and during the initial service discovery.

This is required in cases where a read-only characteristic does not provide notifications but is still able to change its value.

For more details see:
http://lists.qt-project.org/pipermail/interest/2015-March/015673.html