All updated parameters are held temporarily in a RAM buffer, and read back from there if interrogated. The data is permanently stored under the following conditions:
If none of these conditions are met (removal of power before timeout, for instance), parameter values may not be those expected. This could apply if, for example, a logger is programmed via USB, without internal batteries installed and relying on the USB for power. If the USB link is unplugged before the logger has a chance to save any changes made, they will be lost.