If the data logger is logging data in fast sampling mode (the sampling interval was set to less than 5 seconds for Site-Log, iLog Strain Gauge, 1 second for iLog single channel loggers), you must wait for it to complete before making changes or it will stop logging if it detects any communication activity.
If the data logger is logging data in normal sampling mode (the sampling interval was set to 5 seconds or longer for Site-Log, iLog Strain Gauge, 1 second for iLog single channel loggers), Yes, downloading logger won’t affect the logger’s behavior.