Canon WFT-E3 Instruction Manual page 60

Connecting External Media
Unplugging External Media from the USB Port
Before unplugging external media from the USB port, always select [Disconnect] as shown in
step 5. Follow the instructions displayed to terminate the connection.
The connection will not be terminated if you simply turn off the camera and external media. If
you unplug external media while the connection is still active, plug the external media into the
USB port again and follow the preceding steps to terminate the connection.
Power Supply to External Media
External media is powered via the transmitter's USB port as needed. However, external hard
disk drives may not work after connection in some cases.
Power Management
60
If you will not use a wireless or wired LAN at the
same time as the external media, set
[Communication mode] to [Disconnect]. The
camera battery drains faster under settings other
than [Disconnect] because power saving is
disabled.
Setting [Power saving] to [Enable] enables the
power supply to external media to be stopped
automatically, conserving the camera battery.
Power is supplied again automatically during
shooting, when captured images are stored.